The nucleus is the control center of eukaryotic cells that contains DNA. It has a nuclear envelope with pores that regulates transport. The nucleoplasm is a liquid inside the envelope. The nucleolus produces ribosomes. Chromatin contains DNA and proteins. Chromosomes within the nucleus contain DNA and replicate during cell division. The centromere divides each chromosome into two chromatids and determines chromosome shape. The nucleus separates DNA from the cell's metabolic processes and transports materials via the nuclear envelope.
This document discusses chromosome structure and organization. It begins by listing components of chromosomes like centromeres, telomeres, and origins of replication. It then describes how genes are organized between centromeres and telomeres in eukaryotes. Genes can be relatively short with few introns in lower eukaryotes, and longer with many introns in higher eukaryotes. The document also discusses the differences between chromosomes and chromatin, homologous chromosome pairs, autosomes and sex chromosomes, and types of heterochromatin and euchromatin.
The document discusses P-type pumps, also known as SERCA pumps, which are membrane proteins that use ATP to transport ions across membranes. P-type pumps get their name because they use a phosphorylated protein intermediate in their reaction mechanism. Key facts are that they commonly transport calcium, sodium, and potassium ions, use a significant amount of the body's energy, can transport ions in both directions, help maintain osmotic potential and membrane resting potential, and regulate functions by establishing electrochemical gradients, such as the calcium pump in muscle cells.
This document summarizes different types of cell surface receptors. It begins by defining cell surface receptors and their role in signal transduction across the plasma membrane. It then describes the three main components of receptors and three general categories: ion channel-linked receptors, G-protein-linked receptors, and enzyme-linked receptors. For each category, it provides details on their structure and signaling mechanisms. G-protein-linked receptors are discussed in greatest depth, outlining how they signal through G proteins. Receptor tyrosine kinases are provided as an example of enzyme-linked receptors.
The document discusses cell signaling and diseases caused by weak cell signaling. It provides details about:
1) The process of cell signaling and how cells communicate via signaling molecules.
2) Key components of cell signaling pathways like receptors, ligands, and intracellular signaling cascades.
3) Examples of diseases caused by defects in cell signaling pathways like diabetes, multiple sclerosis, and cancer.
4) How treatments for diseases aim to bypass problems in cell signaling pathways.
Chromosomes are organized structures that package DNA and proteins in eukaryotic cells. Bacterial genetic material is concentrated in the nucleoid as a single circular DNA chromosome. Eukaryotic cells contain linear chromosomes housed within the nucleus. Chromosomes are made up of DNA, histone proteins, and non-histone proteins. They contain genes and regulatory elements and vary in structure between species.
Chromosomes are made of chromatin fibers containing DNA and proteins. Each chromosome contains two chromatids joined at the centromere. The centromere divides the chromosome into short and long arms. During cell division, the centromere and attached kinetochore allow chromosomes to align and separate. Telomeres are repetitive DNA sequences at chromosome ends that prevent fusion and shorten with each cell division due to the end replication problem, in which DNA polymerase cannot fully replicate chromosome ends.
This document discusses eukaryotic chromosome organization. It notes that eukaryotic cells contain many chromosomes in the nucleus, with each species having a characteristic number. Chromosomes are made up of DNA and proteins like histones. DNA is wrapped around histones to form structures called nucleosomes, which are further compacted through multiple levels of coiling and folding involving other proteins. This allows the long DNA molecules to fit within cell nuclei.
This document discusses chromosome structure and organization. It begins by listing components of chromosomes like centromeres, telomeres, and origins of replication. It then describes how genes are organized between centromeres and telomeres in eukaryotes. Genes can be relatively short with few introns in lower eukaryotes, and longer with many introns in higher eukaryotes. The document also discusses the differences between chromosomes and chromatin, homologous chromosome pairs, autosomes and sex chromosomes, and types of heterochromatin and euchromatin.
The document discusses P-type pumps, also known as SERCA pumps, which are membrane proteins that use ATP to transport ions across membranes. P-type pumps get their name because they use a phosphorylated protein intermediate in their reaction mechanism. Key facts are that they commonly transport calcium, sodium, and potassium ions, use a significant amount of the body's energy, can transport ions in both directions, help maintain osmotic potential and membrane resting potential, and regulate functions by establishing electrochemical gradients, such as the calcium pump in muscle cells.
This document summarizes different types of cell surface receptors. It begins by defining cell surface receptors and their role in signal transduction across the plasma membrane. It then describes the three main components of receptors and three general categories: ion channel-linked receptors, G-protein-linked receptors, and enzyme-linked receptors. For each category, it provides details on their structure and signaling mechanisms. G-protein-linked receptors are discussed in greatest depth, outlining how they signal through G proteins. Receptor tyrosine kinases are provided as an example of enzyme-linked receptors.
The document discusses cell signaling and diseases caused by weak cell signaling. It provides details about:
1) The process of cell signaling and how cells communicate via signaling molecules.
2) Key components of cell signaling pathways like receptors, ligands, and intracellular signaling cascades.
3) Examples of diseases caused by defects in cell signaling pathways like diabetes, multiple sclerosis, and cancer.
4) How treatments for diseases aim to bypass problems in cell signaling pathways.
Chromosomes are organized structures that package DNA and proteins in eukaryotic cells. Bacterial genetic material is concentrated in the nucleoid as a single circular DNA chromosome. Eukaryotic cells contain linear chromosomes housed within the nucleus. Chromosomes are made up of DNA, histone proteins, and non-histone proteins. They contain genes and regulatory elements and vary in structure between species.
Chromosomes are made of chromatin fibers containing DNA and proteins. Each chromosome contains two chromatids joined at the centromere. The centromere divides the chromosome into short and long arms. During cell division, the centromere and attached kinetochore allow chromosomes to align and separate. Telomeres are repetitive DNA sequences at chromosome ends that prevent fusion and shorten with each cell division due to the end replication problem, in which DNA polymerase cannot fully replicate chromosome ends.
This document discusses eukaryotic chromosome organization. It notes that eukaryotic cells contain many chromosomes in the nucleus, with each species having a characteristic number. Chromosomes are made up of DNA and proteins like histones. DNA is wrapped around histones to form structures called nucleosomes, which are further compacted through multiple levels of coiling and folding involving other proteins. This allows the long DNA molecules to fit within cell nuclei.
Gene regulation in prokaryotes and eukaryotes can occur at multiple levels. In prokaryotes, the lac operon is a classic example of negative gene regulation at the transcription level. The lac operon is induced in the presence of lactose, when the lactose binds to the repressor and inactivates it, allowing transcription. In eukaryotes, gene regulation can occur through transcription factors binding promoter regions to activate transcription, or through displacement factors blocking transcription. Regulation can also occur post-transcriptionally or post-translationally.
Proteins must be properly located within cells to carry out their functions. Protein targeting refers to how cells transport proteins to the correct locations after synthesis. There are several mechanisms for protein targeting. Some proteins diffuse through the cytosol and bind to receptors at their destination site, while others contain targeting sequences like nuclear localization signals that bind nuclear transport receptors to be actively transported into the nucleus. The import and export of proteins between the cytosol and nucleus is directed by gradients of Ran-GTP and Ran-GDP concentrations established by regulatory proteins localized to different cellular compartments. This compartmentalization of Ran states provides directionality to nuclear transport.
ONCOGENE AND PROTOONCOGENE
P53 GENE AND ITS APPLICATION IN CANCER ETIOLOGY
TUMOUR SUPPRESSOR GENE AND BCA AND BAC GENE AND ITS APPLICATION ON THE APOPTOSIS AND DEATH RECEPTORS
Mitochondrial genes are inherited solely from the mother, unlike nuclear genes which are inherited from both parents equally. Mitochondria contain 37 genes that are essential for mitochondrial function. Mitochondrial DNA mutates faster than nuclear DNA due to fewer repair mechanisms and exposure to free radicals during energy production. Mitochondrial DNA is also inherited differently, with mutations able to exist across different mitochondria within the same cell.
The document discusses the nucleosome model of chromosome structure. It describes how DNA wraps around histone proteins to form nucleosomes, which are the basic units of chromatin. Specifically:
- Nucleosomes consist of 146-166 base pairs of DNA wrapped around an octamer of core histone proteins H2A, H2B, H3, and H4.
- Linker histone H1 binds to the DNA as it enters and exits each nucleosome, forming a structure known as a chromatosome.
- Adjacent nucleosomes are joined by 10-80 base pairs of linker DNA. The histone proteins and DNA interact via ionic bonds between negatively charged DNA and positively charged residues on
Apoptosis is a tightly regulated and controlled process of programmed cell death. It is essential for normal development and maintenance of tissues as it removes unnecessary or damaged cells. During apoptosis, cells activate enzymes to degrade their own DNA and proteins. Apoptosis is initiated through either the extrinsic or intrinsic pathway which involve death ligands/receptors or mitochondrial signaling, respectively, ultimately activating caspase enzymes that kill the cell in a controlled manner. Apoptosis is important for development, the immune system, and removing pre-cancerous or infected cells, while deficiencies can lead to cancer or autoimmune disorders.
Telomeres are repetitive DNA sequences that cap the ends of chromosomes. They contain the sequence TTAGGG and associated proteins that help protect chromosome ends from damage or fusion. As cells divide, telomeres slowly shorten due to the end replication problem. Once telomeres reach a critical short length, cells enter a permanent state of growth arrest called senescence. The enzyme telomerase helps maintain telomere length by adding back TTAGGG repeats and allowing cells to avoid senescence and continue dividing. Telomeres and telomerase play important roles in aging, cellular replication limits, and preventing chromosome fusion.
This document discusses the process of translation in cells. It defines translation as the process by which the genetic information in messenger RNA (mRNA) is used to direct the synthesis of proteins. The key components involved in translation are mRNA, transfer RNA (tRNA), aminoacyl-tRNA synthetases, and ribosomes. Translation involves tRNAs carrying amino acids to the ribosome, where they are linked together into a polypeptide chain according to the codons in the mRNA.
The document discusses the Michaelis-Menten equation, which was devised in 1913 to explain the relationship between reaction velocity and substrate concentration in enzyme-catalyzed reactions. It is based on the assumption that the enzyme and substrate form a reversible enzyme-substrate complex in the initial step of the reaction. The Michaelis constant Km represents the substrate concentration at which the reaction velocity is half of its maximum value Vmax and can be used to measure the enzyme's affinity for the substrate. The Lineweaver-Burk plot is also described as a way to determine Km and Vmax values graphically from experimental data.
This document discusses the structures and functions of heterochromatin and euchromatin. Heterochromatin is tightly packed and transcriptionally inactive, found near centromeres and telomeres. Euchromatin is loosely packed and contains most actively transcribed genes. The basic unit of DNA packing is the nucleosome, which involves DNA wound around histone proteins. Heterochromatin and euchromatin differ in their genetic activity, location within chromosomes, and condensation levels during interphase.
Chloroplasts are organelles found in plants and algae that carry out photosynthesis. They have an inner and outer membrane, with an intermembrane space between them. Inside is the stroma, which contains thylakoids that are arranged in stacks called grana. Chloroplasts contain their own genome and divide independently. According to the endosymbiotic theory, chloroplasts originated from cyanobacteria that were engulfed by other cells but not destroyed. Chloroplasts import most proteins from the cytosol through translocation complexes in the inner and outer membranes. They perform photosynthesis through light and dark reactions, using solar energy to fix carbon dioxide and produce oxygen and carbohydrates.
Cell signaling involves the use of signaling molecules to transmit information between cells. These molecules can be classified as extracellular signals, like peptides, lipids, gases, and small hydrophilic molecules, or intracellular second messengers like cAMP and calcium. Extracellular signals bind to cell surface receptors and trigger intracellular pathways that regulate cell function and development. Signaling can occur through endocrine, paracrine, or autocrine pathways depending on the distance over which the signal acts. Important examples of signaling molecules discussed include peptide hormones, steroid hormones, prostaglandins, and nitric oxide. Intracellular signaling molecules like G proteins and protein kinases transmit and amplify extracellular signals within cells through the use of feedback loops and molecular switches. Breakdowns
This document discusses the organization of chromatin and DNA packaging in the cell nucleus. It describes four main levels of chromatin organization: 1) DNA wraps around histone proteins to form nucleosomes, the basic unit of chromatin, 2) Nucleosomes further organize into 30nm fibers, 3) The 30nm fibers then organize into looped domains, and 4) During cell division, the loops compact into mitotic chromosomes. Nucleosomes consist of about 150 base pairs of DNA wrapped around an octamer of core histone proteins, and act to tightly package DNA inside the nucleus.
The document discusses the Michaelis Menten equation, which is a mathematical description of the rate of enzyme-catalyzed reactions. It provides references for learning more about the fundamental biochemistry concepts from textbooks by Dr. Sathyanarayana and Dr. B.B. Singh as well as online sources like www.sciencedirect.in and www.researchgate.net. The document also thanks the reader.
The document discusses the biological membrane and its chemical composition. It notes that the plasma membrane is the outer boundary of cells, consisting of a double layer of lipid molecules with embedded proteins. The major components of membranes are glycerophospholipids, sphingolipids, and cholesterol. Glycerophospholipids are amphipathic lipids that form the lipid bilayer structure. The fluid mosaic model describes membranes as a fluid structure with lipids and proteins able to move laterally. Membrane proteins can be integral or peripheral, and help with cell functions like transport and signaling. Membrane fluidity is influenced by temperature and lipid composition.
Types of chromosomes, basic structural features, chromosomal numbers, chromosomal banding, molecular organization of eukaryotic chromosome, MARS/SARS. Heterochromatin, euchromatin structures; structural organization of centromeric region, components and structure of Kinetochore, difference between mitotic kinetochores and meiotic kinetochores; structural organization of telomeres, proteins involved in heterochromatization of telomeric regions. Structural organization and molecular biology of salivary gland and Lampbrush chromosomes, importance of their study at specific stages of development.
This document discusses chromosome structure and organization with respect to nucleosomes. It begins by defining genetic material and describing its forms in prokaryotes and eukaryotes. It then discusses the components of chromatin, including histone and non-histone proteins. It describes how DNA wraps around histone proteins to form nucleosomes, and how nucleosomes further organize into higher-order structures like the 30nm fiber. The document concludes by explaining how condensin proteins facilitate chromosome condensation during cell division.
The Golgi apparatus, also known as the Golgi complex, Golgi body, or simply the Golgi, is an organelle found in most eukaryotic cells.
It is of particular importance in processing proteins for secretion, containing a set of glycosylation enzymes that attach various sugar monomers to proteins as the proteins move through the apparatus.
here u will find every detail of golgi.
Mitochondrial biogenesis is the process by which cells increase mitochondrial numbers. It was first described by John Holloszy in the 1960s, when it was discovered that physical endurance training induced higher mitochondrial content levels, leading to greater glucose uptake by muscles. Mitochondrial biogenesis is activated by numerous different signals during times of cellular stress or in response to environmental stimuli, such as aerobic exercise.
This document discusses the morphology and types of chromosomes. It begins by defining what a chromosome is and where they are located in prokaryotic and eukaryotic cells. It then describes the different structural features of chromosomes visible under a light microscope, including chromatids, centromeres, secondary constrictions, telomeres, and satellites. It explains the different types of chromosomes based on centromere position, number of centromeres, size, and composition. The key differences between heterochromatin and euchromatin are also summarized.
Chromosomes are DNA molecules that package genes and hereditary material. They exist in eukaryotic cells and contain DNA, proteins, and regulatory elements. Chromosomes have a complex structure, condensing through multiple levels to form compact metaphase chromosomes. They vary in size, shape, and number between species. Special types of chromosomes include polytene chromosomes found in insect larvae and lampbrush chromosomes seen during vertebrate meiosis. Karyotyping allows identification of chromosomes based on number, length, centromere position, and other features. Staining techniques are used to visualize chromosomes and study their structure.
Gene regulation in prokaryotes and eukaryotes can occur at multiple levels. In prokaryotes, the lac operon is a classic example of negative gene regulation at the transcription level. The lac operon is induced in the presence of lactose, when the lactose binds to the repressor and inactivates it, allowing transcription. In eukaryotes, gene regulation can occur through transcription factors binding promoter regions to activate transcription, or through displacement factors blocking transcription. Regulation can also occur post-transcriptionally or post-translationally.
Proteins must be properly located within cells to carry out their functions. Protein targeting refers to how cells transport proteins to the correct locations after synthesis. There are several mechanisms for protein targeting. Some proteins diffuse through the cytosol and bind to receptors at their destination site, while others contain targeting sequences like nuclear localization signals that bind nuclear transport receptors to be actively transported into the nucleus. The import and export of proteins between the cytosol and nucleus is directed by gradients of Ran-GTP and Ran-GDP concentrations established by regulatory proteins localized to different cellular compartments. This compartmentalization of Ran states provides directionality to nuclear transport.
ONCOGENE AND PROTOONCOGENE
P53 GENE AND ITS APPLICATION IN CANCER ETIOLOGY
TUMOUR SUPPRESSOR GENE AND BCA AND BAC GENE AND ITS APPLICATION ON THE APOPTOSIS AND DEATH RECEPTORS
Mitochondrial genes are inherited solely from the mother, unlike nuclear genes which are inherited from both parents equally. Mitochondria contain 37 genes that are essential for mitochondrial function. Mitochondrial DNA mutates faster than nuclear DNA due to fewer repair mechanisms and exposure to free radicals during energy production. Mitochondrial DNA is also inherited differently, with mutations able to exist across different mitochondria within the same cell.
The document discusses the nucleosome model of chromosome structure. It describes how DNA wraps around histone proteins to form nucleosomes, which are the basic units of chromatin. Specifically:
- Nucleosomes consist of 146-166 base pairs of DNA wrapped around an octamer of core histone proteins H2A, H2B, H3, and H4.
- Linker histone H1 binds to the DNA as it enters and exits each nucleosome, forming a structure known as a chromatosome.
- Adjacent nucleosomes are joined by 10-80 base pairs of linker DNA. The histone proteins and DNA interact via ionic bonds between negatively charged DNA and positively charged residues on
Apoptosis is a tightly regulated and controlled process of programmed cell death. It is essential for normal development and maintenance of tissues as it removes unnecessary or damaged cells. During apoptosis, cells activate enzymes to degrade their own DNA and proteins. Apoptosis is initiated through either the extrinsic or intrinsic pathway which involve death ligands/receptors or mitochondrial signaling, respectively, ultimately activating caspase enzymes that kill the cell in a controlled manner. Apoptosis is important for development, the immune system, and removing pre-cancerous or infected cells, while deficiencies can lead to cancer or autoimmune disorders.
Telomeres are repetitive DNA sequences that cap the ends of chromosomes. They contain the sequence TTAGGG and associated proteins that help protect chromosome ends from damage or fusion. As cells divide, telomeres slowly shorten due to the end replication problem. Once telomeres reach a critical short length, cells enter a permanent state of growth arrest called senescence. The enzyme telomerase helps maintain telomere length by adding back TTAGGG repeats and allowing cells to avoid senescence and continue dividing. Telomeres and telomerase play important roles in aging, cellular replication limits, and preventing chromosome fusion.
This document discusses the process of translation in cells. It defines translation as the process by which the genetic information in messenger RNA (mRNA) is used to direct the synthesis of proteins. The key components involved in translation are mRNA, transfer RNA (tRNA), aminoacyl-tRNA synthetases, and ribosomes. Translation involves tRNAs carrying amino acids to the ribosome, where they are linked together into a polypeptide chain according to the codons in the mRNA.
The document discusses the Michaelis-Menten equation, which was devised in 1913 to explain the relationship between reaction velocity and substrate concentration in enzyme-catalyzed reactions. It is based on the assumption that the enzyme and substrate form a reversible enzyme-substrate complex in the initial step of the reaction. The Michaelis constant Km represents the substrate concentration at which the reaction velocity is half of its maximum value Vmax and can be used to measure the enzyme's affinity for the substrate. The Lineweaver-Burk plot is also described as a way to determine Km and Vmax values graphically from experimental data.
This document discusses the structures and functions of heterochromatin and euchromatin. Heterochromatin is tightly packed and transcriptionally inactive, found near centromeres and telomeres. Euchromatin is loosely packed and contains most actively transcribed genes. The basic unit of DNA packing is the nucleosome, which involves DNA wound around histone proteins. Heterochromatin and euchromatin differ in their genetic activity, location within chromosomes, and condensation levels during interphase.
Chloroplasts are organelles found in plants and algae that carry out photosynthesis. They have an inner and outer membrane, with an intermembrane space between them. Inside is the stroma, which contains thylakoids that are arranged in stacks called grana. Chloroplasts contain their own genome and divide independently. According to the endosymbiotic theory, chloroplasts originated from cyanobacteria that were engulfed by other cells but not destroyed. Chloroplasts import most proteins from the cytosol through translocation complexes in the inner and outer membranes. They perform photosynthesis through light and dark reactions, using solar energy to fix carbon dioxide and produce oxygen and carbohydrates.
Cell signaling involves the use of signaling molecules to transmit information between cells. These molecules can be classified as extracellular signals, like peptides, lipids, gases, and small hydrophilic molecules, or intracellular second messengers like cAMP and calcium. Extracellular signals bind to cell surface receptors and trigger intracellular pathways that regulate cell function and development. Signaling can occur through endocrine, paracrine, or autocrine pathways depending on the distance over which the signal acts. Important examples of signaling molecules discussed include peptide hormones, steroid hormones, prostaglandins, and nitric oxide. Intracellular signaling molecules like G proteins and protein kinases transmit and amplify extracellular signals within cells through the use of feedback loops and molecular switches. Breakdowns
This document discusses the organization of chromatin and DNA packaging in the cell nucleus. It describes four main levels of chromatin organization: 1) DNA wraps around histone proteins to form nucleosomes, the basic unit of chromatin, 2) Nucleosomes further organize into 30nm fibers, 3) The 30nm fibers then organize into looped domains, and 4) During cell division, the loops compact into mitotic chromosomes. Nucleosomes consist of about 150 base pairs of DNA wrapped around an octamer of core histone proteins, and act to tightly package DNA inside the nucleus.
The document discusses the Michaelis Menten equation, which is a mathematical description of the rate of enzyme-catalyzed reactions. It provides references for learning more about the fundamental biochemistry concepts from textbooks by Dr. Sathyanarayana and Dr. B.B. Singh as well as online sources like www.sciencedirect.in and www.researchgate.net. The document also thanks the reader.
The document discusses the biological membrane and its chemical composition. It notes that the plasma membrane is the outer boundary of cells, consisting of a double layer of lipid molecules with embedded proteins. The major components of membranes are glycerophospholipids, sphingolipids, and cholesterol. Glycerophospholipids are amphipathic lipids that form the lipid bilayer structure. The fluid mosaic model describes membranes as a fluid structure with lipids and proteins able to move laterally. Membrane proteins can be integral or peripheral, and help with cell functions like transport and signaling. Membrane fluidity is influenced by temperature and lipid composition.
Types of chromosomes, basic structural features, chromosomal numbers, chromosomal banding, molecular organization of eukaryotic chromosome, MARS/SARS. Heterochromatin, euchromatin structures; structural organization of centromeric region, components and structure of Kinetochore, difference between mitotic kinetochores and meiotic kinetochores; structural organization of telomeres, proteins involved in heterochromatization of telomeric regions. Structural organization and molecular biology of salivary gland and Lampbrush chromosomes, importance of their study at specific stages of development.
This document discusses chromosome structure and organization with respect to nucleosomes. It begins by defining genetic material and describing its forms in prokaryotes and eukaryotes. It then discusses the components of chromatin, including histone and non-histone proteins. It describes how DNA wraps around histone proteins to form nucleosomes, and how nucleosomes further organize into higher-order structures like the 30nm fiber. The document concludes by explaining how condensin proteins facilitate chromosome condensation during cell division.
The Golgi apparatus, also known as the Golgi complex, Golgi body, or simply the Golgi, is an organelle found in most eukaryotic cells.
It is of particular importance in processing proteins for secretion, containing a set of glycosylation enzymes that attach various sugar monomers to proteins as the proteins move through the apparatus.
here u will find every detail of golgi.
Mitochondrial biogenesis is the process by which cells increase mitochondrial numbers. It was first described by John Holloszy in the 1960s, when it was discovered that physical endurance training induced higher mitochondrial content levels, leading to greater glucose uptake by muscles. Mitochondrial biogenesis is activated by numerous different signals during times of cellular stress or in response to environmental stimuli, such as aerobic exercise.
This document discusses the morphology and types of chromosomes. It begins by defining what a chromosome is and where they are located in prokaryotic and eukaryotic cells. It then describes the different structural features of chromosomes visible under a light microscope, including chromatids, centromeres, secondary constrictions, telomeres, and satellites. It explains the different types of chromosomes based on centromere position, number of centromeres, size, and composition. The key differences between heterochromatin and euchromatin are also summarized.
Chromosomes are DNA molecules that package genes and hereditary material. They exist in eukaryotic cells and contain DNA, proteins, and regulatory elements. Chromosomes have a complex structure, condensing through multiple levels to form compact metaphase chromosomes. They vary in size, shape, and number between species. Special types of chromosomes include polytene chromosomes found in insect larvae and lampbrush chromosomes seen during vertebrate meiosis. Karyotyping allows identification of chromosomes based on number, length, centromere position, and other features. Staining techniques are used to visualize chromosomes and study their structure.
Chromosomes are structures within the nucleus that contain DNA. They become visible during cell division and are the carriers of genetic information. Chromosomes are composed of chromatin fibers that coil and fold, making the chromosomes visible under a light microscope during cell division. Chromosomes vary in size and number between species. They contain DNA that is packaged with histone proteins to form chromatin. The basic repeating unit of chromatin is the nucleosome, which contains 146 base pairs of DNA wrapped around an octamer of histone proteins.
Chromosomes are structures that carry genetic information in the form of DNA. They are located within the nucleus of cells.
Chromosomes contain genes arranged in specific locations along chromatin. Different species have varying numbers of chromosomes depending on their genome size. Chromosomes contain features like centromeres, chromatids, and telomeres that allow for their movement and protection during cell division. Chromosomes are classified based on centromere position and carry out essential functions like cell division, inheritance of traits, and sex determination.
Chromosomes are structures within the nucleus that carry genetic information. They are composed of DNA and proteins and are only visible during cell division. Chromosomes contain genes and come in varying numbers depending on the organism. They are organized into nucleosomes which aid in compactly packaging the long DNA molecules. Centromeres and telomeres are essential features that help segregate and provide stability to chromosomes during cell division.
Chromosomes are structures found within cells that carry genetic information. There are three main types - viral, prokaryotic, and eukaryotic. Eukaryotic chromosomes are found within the cell nucleus and are made of DNA and proteins. They vary in number, size, shape and other characteristics between different species. The cell cycle involves growth and DNA replication during interphase, followed by nuclear division through mitosis and cytoplasmic division through cytokinesis.
Chromosomes are structures in the nucleus that carry genetic information from one generation to the next. They play a vital role in cell division, heredity, and genetic inheritance. Chromosomes are made up of DNA and proteins, and vary in size, shape, and number between different species. They have various structures like chromatids, centromeres, and telomeres that allow them to duplicate and segregate accurately during cell division. Specific types of chromosomes include polytene chromosomes found in insect cells and lampbrush chromosomes found in animal oocytes. Chromosomes function to protect DNA and regulate gene expression essential for growth, reproduction, and repair of organisms.
This document provides an overview of the key topics that will be covered in a chapter about the cell, including ribosomes, cytoskeleton, cilia and flagella, centrosome, centrioles, nucleus, and microbodies. It describes the structure and functions of these various cellular components at a high level.
Chromosomes are structures within cells that carry genetic information in the form of DNA. They exist in pairs and humans normally have 46 chromosomes total. Chromosomes are made up of DNA, proteins, and are visible during cell division. They compact DNA and carry genes that code for the production of proteins and inheritance of traits. Chromosomes undergo different levels of coiling and condensation within cells and can be classified based on features like centromere placement and size.
The document discusses chromosomes and provides details about their structure and composition. It defines chromosomes as thread-like structures made of DNA and proteins that are found inside the nucleus and are visible during cell division. It describes the key components of chromosomes, including DNA, histones, centromeres, and telomeres. It also summarizes different models of chromosome structure, including the folded fiber model and the nucleosome model, which explains how DNA interacts with histone proteins to form repeating nucleosome units in eukaryotic chromosomes.
Chromosome structure and packaging of dnaDIPTI NARWAL
Chromosomes are structures that contain DNA and help transmit genetic information from parents to offspring. They exist in the nucleus of cells and vary in number between species. DNA is packaged into chromosomes through histone proteins that allow very long DNA strands to fit inside cells. DNA wraps around histone proteins to form structures called nucleosomes, which contain 147 base pairs of DNA wrapped around an octamer of histone proteins. Nucleosomes further compact DNA by forming a beads-on-a-string structure that can coil and fold, allowing the long DNA molecules to fit within cells.
The document discusses the cell nucleus and its components. Key points include:
- The nucleus contains DNA and directs cell functions and protein production through transcription and RNA processing.
- It is surrounded by a double membrane with nuclear pores that regulate transport between the nucleus and cytoplasm.
- The nucleus contains chromatin (DNA and proteins) and the nucleolus, which is the site of ribosomal RNA transcription and ribosome assembly.
- DNA replication and cell division are regulated by the nucleus.
Chromosomes are structures within cells that carry genetic information in the form of DNA. They are only visible during cell division. Chromosomes are composed of chromatin fibers that coil and fold, making the chromosomes visible under a light microscope during cell division. The number and size of chromosomes vary between species but provide the basic genetic information. Key parts of chromosomes include the centromere, which divides the chromosome into arms and attaches to spindle fibers during cell division, and the telomeres at the ends, which provide stability.
The Greek words "Chroma," which means colour, and "Soma," which means body, were combined to create the English word "chromosome." They are distinct cell organelles made of chromatin, the most significant and durable component of the cell nucleus. They have the ability to reproduce themselves. They are important for differentiation, heredity, mutation, and evolution and regulate the structure and metabolism of cells.
General History of Chromosomes
Nuclear filaments were found by W. Hofmeister in the Tradescantia pollen mother cells' nuclei in 1848. W. Flemming conducted the first precise chromosome count in a cell's nucleus in 1882. W. Flemming, Evan Beneden, and E. Strasburger showed in 1884 that the chromosomes double in number during mitosis through longitudinal division. Beneden discovered that each species had a fixed number of chromosomes in 1887. W. Waldeyer first used the term "chromosomes" for the nuclear filaments in 1888. The role of chromosomes in heredity was first proposed by W.S. Sutton and T. Boveri in 1902, and it was later supported by Morgan in 1933.
In viruses, prokaryotes, and eukaryotes, chromosome structures differ.
1. Viral chromosome- In viruses, each chromosome contains a single nucleic acid molecule (DNA or RNA), which is encased in a protein coat known as the capsid. It could be circular or linear. The term "DNA virus" refers to viruses with DNA as their genetic material, while the term "RNA virus" refers to viruses with RNA as their genetic material. The viral chromosome contains a small amount of genetic material that primarily regulates the generation of additional identical virus particles in the host cell. In RNA viruses, the RNA frequently instructs the host's reverse transcription process to create DNA that is complementary to itself.
The DNA then uses the RNA to create new viral particles by transcribing it. Retroviruses are one type of ribovirus. A retrovirus is what causes AIDS.
2. Prokaryotic chromosomes- A single circular two-stranded DNA molecule found on prokaryotic chromosomes, such as those found in bacteria, is not encased by any membrane. It is in direct contact with the cytoplasm and is protein-free.
Some RNA that seems to form a core encases the bacterial chromosome in the nucleoid. At some point, it is anchored permanently to the plasma membrane. Most bacterial cells also contain some extra-chromosomal DNA molecules that are double stranded and circular but much smaller in size than the main chromosome. Plasmids are the name for them.
The plasmid can appear on its own in the cytoplasm of cells or it can also be discovered in associated with the main chromosomal DNA and is known as an episome.
3. Eukaryotic chromosomes- The nucleus and some other organelles, like mitochondria and plastids, contain the eukaryotic chromosomes. Nuclear and extra nuclear chromosomes are the names given to these chromosomes, respectively.
Double-stranded, linear, long DNA molecules make up nuclear chromosomes. They are
presentation on chromosome morphology and karyotypeasifaslam76778
The document discusses the structure and composition of chromosomes. It defines key terms like chromatid, centromere, and telomere. It describes the four classes of chromosomes based on centromere position - metacentric, submetacentric, acrocentric, and telocentric. The document also discusses heterochromatin, euchromatin, karyotypes, and the chemical composition of chromosomes, including DNA, histones, and non-histone proteins.
Chromosomes are organized structures found in cells that contain DNA and proteins. Each chromosome is made of DNA coiled around histone proteins. Chromosomes are located in the cell nucleus and are passed from parents to offspring. They are named because they can be stained with dyes. In most organisms, chromosomes occur in homologous pairs. The human body contains 23 pairs of chromosomes. Chromosomes condense and can be observed during cell division. They contain duplicated copies called sister chromatids joined at the centromere. Chemically, chromosomes contain DNA, RNA, histone and non-histone proteins, and metal ions. According to the folded fiber model, each chromosome consists of a single DNA molecule wrapped around proteins and folded into a
Chromosomes are thread-like structures in the nucleus that contain DNA. They condense during cell division and duplicate their DNA before splitting into two identical copies in each daughter cell. The number and structure of chromosomes provide important genetic information. Key points are that chromosomes contain DNA, duplicate before cell division, and determine species traits through their number and structure.
Chromosomes are structures that contain DNA and play several important roles in the cell. They package and organize the genome, act as the basic units of heredity during cell division, and determine traits by controlling which genes are expressed. Chromosomes are made up of DNA, histone proteins, and other components. In eukaryotes, DNA is wrapped around histones to form nucleosomes, which condense into chromatin and further condense into visible chromosomes during cell division. Prokaryotes have single circular chromosomes while eukaryotes chromosomes are linear and located within the nucleus. Chromosomes ensure accurate replication and transmission of genetic material between parent and daughter cells.
Cells are the fundamental units of life, and all organisms are made up of one or more cells. The document discusses two important cellular components - the nucleus and ribosomes. The nucleus houses most of the cell's DNA and directs protein synthesis. It is enclosed by a double membrane and contains chromosomes. The ribosomes use information from DNA to synthesize proteins according to instructions provided by messenger RNA. They assemble in the nucleolus and exit into the cytoplasm to perform protein synthesis.
Minimize seed deterioration during it’s storage of orthodox or recalcitrant s...AKHILRDONGA
PG major SEMINAR on minimize seed deterioration during its storage of orthodox or recalcitrant seed ppt file delivered by Pratik Bhankhar (M.Sc. Seed Science and Technology) at C. P. College of Agriculture, S. D. Agricultural University, Sardarkrushinagar.
it contains How to minimize the seed deterioration during its storage.
BREEDING FOR VIRUS RESISTANCE IN PULSES.pptxAKHILRDONGA
PG major SEMINAR on BREEDING FOR VIRUS RESISTANCE IN PULSES ppt file delivered by Dheeraj Bamaniya from M.Sc. (Genetics and Plant breeding) in C. P. college of agriculture, S. D. Agricultural University, Sardarkrushinagar. it Contains how to develop virus-resistant varieties in pulse crops
Role of Biotechnological Approaches in Underutilized Tropical Fruit Improveme...AKHILRDONGA
PG SEMINAR on Role of Biotechnological Approaches in Underutilized Tropical Fruit Improvements ppt file delivered by Hardiksinh Chavda (M.Sc. in Plant molecular biology and biotechnology) at C. P. College of Agriculture, S. D. Agricultural University, Sardarkrushinagar.
RECENT STUDIES ON SYNTHETIC SEED PRODUCTION IN HORTICULTURAL CROPS.pptxAKHILRDONGA
This document discusses two case studies on the production of synthetic seeds.
The first case study examines optimization of synthetic seed production for potato by encapsulating axillary buds in sodium alginate. It finds the highest regrowth rates used 2.5% sodium alginate, 1.5% calcium chloride, buds 2-3mm in size, and full strength MS medium. Coco peat was the best substrate for plantlet conversion.
The second case study focuses on synthetic seed production for hybrid citrus. It finds 4% sodium alginate provides firm, isometric seeds with the highest conversion after cold storage. MS medium with hormones achieved the highest conversion of encapsulated shoot tips after storage. Different media
The document discusses translation, the process by which proteins are synthesized from messenger RNA (mRNA) templates. It describes the key components of translation, including mRNA, transfer RNA (tRNA), ribosomes, and enzymes. The translation process involves three main steps: initiation, elongation, and termination. Initiation involves the assembly of the ribosomal complex on the mRNA. Elongation is the cyclic addition of amino acids to the growing polypeptide chain. Termination occurs when a stop codon is reached, releasing the complete protein. The document also discusses various mechanisms of regulating translation, such as via RNA-binding proteins, the 5' and 3' untranslated regions, microRNAs, and phosphorylation of initiation factors.
The document summarizes eukaryotic transcription and its regulation. It discusses the core promoter elements, pre-initiation complex formation, the three phases of transcription (initiation, elongation, termination), and the role of RNA polymerase and general transcription factors. It also describes mRNA processing events like capping, splicing, and polyadenylation. Finally, it discusses mechanisms of transcriptional regulation including cis-regulatory elements like promoters and enhancers, the role of chromatin structure, and common DNA-binding domains in transcription factors.
Mechanism of Recombination in Prokaryotes and Eukaryotes FINAL.pptxAKHILRDONGA
This document summarizes mechanisms of genetic recombination in prokaryotes and eukaryotes. It discusses that recombination involves the formation of new gene combinations through processes like transformation, transduction, and conjugation in prokaryotes. In eukaryotes, homologous recombination is the main mechanism, which can occur through the Holliday model or the double-stranded break repair model. Specific examples of each mechanism are provided, such as the steps of transformation and transduction in prokaryotes.
Nucleic acids are biopolymers composed of nucleotides that contain a 5-carbon sugar (either ribose or deoxyribose), phosphate group, and a nitrogenous base. There are two main types of nucleic acids: DNA and RNA. DNA contains the genetic instructions and usually takes the form of a double-stranded helix. RNA is involved in encoding, decoding, regulating, and expressing genes and exists in several types, including mRNA, tRNA, and rRNA. Nucleic acids are essential components of all living organisms that carry the genetic information needed to direct protein synthesis.
Plastids are membrane-bound organelles found in plant and algal cells that often contain pigments used in photosynthesis. There are several types of plastids that serve different functions: chloroplasts contain chlorophyll and are the site of photosynthesis; chromoplasts contain carotenoids and synthesize and store pigments; gerontoplasts are involved in chloroplast degradation during senescence; and leucoplasts like amyloplasts, elaioplasts, and proteinoplasts store starches, lipids, and proteins respectively. It is believed that plastids evolved from endosymbiotic cyanobacteria that were engulfed by plant cells and eventually became specialized organelles.
Golgi bodies, lysosomes, peroxisomes, and glyoxysomes are intracellular organelles that have important structural and functional roles in eukaryotic cells. Golgi bodies package and transport proteins and lipids within cells. Lysosomes contain digestive enzymes and help degrade and recycle cellular components. Peroxisomes produce hydrogen peroxide and are involved in lipid metabolism. Glyoxysomes facilitate the breakdown of stored lipids into carbohydrates during seed germination. These organelles work collaboratively and with other cell structures to carry out vital biochemical processes.
Mitochondria are double-membrane organelles found in eukaryotic cells that produce energy through cellular respiration. They contain their own circular DNA and reproduce through binary fission like bacteria. The widely accepted endosymbiotic theory proposes that mitochondria originated from engulfed aerobic prokaryotes that developed a symbiotic relationship with the host cell. Mitochondria have an outer and inner membrane, as well as cristae and matrix. They play essential roles in cellular respiration to generate ATP as well as other functions like calcium storage and apoptosis. Manipulating the mitochondrial genome could provide advantages for crop improvement by enabling maternal inheritance of transgenes to reduce gene escape.
The plant cell wall is a complex structure outside the cell membrane that provides structure and protection to the cell. It is made up of three main layers - the middle lamella, primary cell wall, and secondary cell wall. The primary cell wall is thin and elastic in young cells, and contains cellulose fibrils, hemicellulose, and pectin. As the cell matures, the secondary cell wall is deposited between the primary cell wall and cell contents. It is rigid and made mostly of cellulose and lignin. Together, the cell wall layers strengthen the plant body and play important roles in growth, differentiation, and defense.
Prokaryotic cells have a simpler structure than eukaryotic cells and lack membrane-bound organelles. They have a cell wall and plasma membrane, but interior structures like the cytoplasm lack internal membranes. The genetic material is not enclosed in a nucleus. Some prokaryotes like bacteria have a peptidoglycan cell wall, while others like archaea have different cell wall compositions. Surface structures can include flagella, pili, or fimbriae. Binary fission is how prokaryotes replicate.
Seminar on Genetic improvement in cucumber.pptxAKHILRDONGA
PG major Seminar on Genetic Improvement in cucumber ppt file delivered by Akhil Donga (M.Sc. Genetics and plant Breeding) in C. P. College of Agriculture, S. D. Agricultural University, Sardarkrushinagar.
Assign. GP 506 sex linked genes AD.pptxAKHILRDONGA
This document discusses genetic equilibrium for sex-linked genes. It provides details on:
1) Sex-linked genes are located on sex chromosomes and are inherited differently between males and females. Females have two X chromosomes while males have one X and one Y chromosome.
2) At genetic equilibrium, allelic frequencies are the same between males and females when mating is random. The expected progeny frequencies equal the parental frequencies.
3) Properties of genetic equilibrium populations include gene frequencies remaining constant over generations and the difference in frequencies between sexes decreasing by half each generation.
7_DNA organization in prokaryotes and eukaryotes.pptxAKHILRDONGA
DNA is the molecule that contains the genetic instructions used in the development and functioning of all known living organisms. In prokaryotes, DNA exists as a single circular chromosome located in the nucleoid region of the cell. Prokaryotic DNA is tightly packed using supercoiling, where the DNA winds further around itself. In eukaryotes, DNA is organized into linear chromosomes within the cell nucleus. Eukaryotic DNA is associated with histone proteins to form chromatin, which condenses into distinct chromosomes during cell division. The basic unit of hereditary information is the gene. Genes encode either functional products like proteins or regulatory elements that control gene expression.
The use of Nauplii and metanauplii artemia in aquaculture (brine shrimp).pptxMAGOTI ERNEST
Although Artemia has been known to man for centuries, its use as a food for the culture of larval organisms apparently began only in the 1930s, when several investigators found that it made an excellent food for newly hatched fish larvae (Litvinenko et al., 2023). As aquaculture developed in the 1960s and ‘70s, the use of Artemia also became more widespread, due both to its convenience and to its nutritional value for larval organisms (Arenas-Pardo et al., 2024). The fact that Artemia dormant cysts can be stored for long periods in cans, and then used as an off-the-shelf food requiring only 24 h of incubation makes them the most convenient, least labor-intensive, live food available for aquaculture (Sorgeloos & Roubach, 2021). The nutritional value of Artemia, especially for marine organisms, is not constant, but varies both geographically and temporally. During the last decade, however, both the causes of Artemia nutritional variability and methods to improve poorquality Artemia have been identified (Loufi et al., 2024).
Brine shrimp (Artemia spp.) are used in marine aquaculture worldwide. Annually, more than 2,000 metric tons of dry cysts are used for cultivation of fish, crustacean, and shellfish larva. Brine shrimp are important to aquaculture because newly hatched brine shrimp nauplii (larvae) provide a food source for many fish fry (Mozanzadeh et al., 2021). Culture and harvesting of brine shrimp eggs represents another aspect of the aquaculture industry. Nauplii and metanauplii of Artemia, commonly known as brine shrimp, play a crucial role in aquaculture due to their nutritional value and suitability as live feed for many aquatic species, particularly in larval stages (Sorgeloos & Roubach, 2021).
The ability to recreate computational results with minimal effort and actionable metrics provides a solid foundation for scientific research and software development. When people can replicate an analysis at the touch of a button using open-source software, open data, and methods to assess and compare proposals, it significantly eases verification of results, engagement with a diverse range of contributors, and progress. However, we have yet to fully achieve this; there are still many sociotechnical frictions.
Inspired by David Donoho's vision, this talk aims to revisit the three crucial pillars of frictionless reproducibility (data sharing, code sharing, and competitive challenges) with the perspective of deep software variability.
Our observation is that multiple layers — hardware, operating systems, third-party libraries, software versions, input data, compile-time options, and parameters — are subject to variability that exacerbates frictions but is also essential for achieving robust, generalizable results and fostering innovation. I will first review the literature, providing evidence of how the complex variability interactions across these layers affect qualitative and quantitative software properties, thereby complicating the reproduction and replication of scientific studies in various fields.
I will then present some software engineering and AI techniques that can support the strategic exploration of variability spaces. These include the use of abstractions and models (e.g., feature models), sampling strategies (e.g., uniform, random), cost-effective measurements (e.g., incremental build of software configurations), and dimensionality reduction methods (e.g., transfer learning, feature selection, software debloating).
I will finally argue that deep variability is both the problem and solution of frictionless reproducibility, calling the software science community to develop new methods and tools to manage variability and foster reproducibility in software systems.
Exposé invité Journées Nationales du GDR GPL 2024
BREEDING METHODS FOR DISEASE RESISTANCE.pptxRASHMI M G
Plant breeding for disease resistance is a strategy to reduce crop losses caused by disease. Plants have an innate immune system that allows them to recognize pathogens and provide resistance. However, breeding for long-lasting resistance often involves combining multiple resistance genes
The debris of the ‘last major merger’ is dynamically youngSérgio Sacani
The Milky Way’s (MW) inner stellar halo contains an [Fe/H]-rich component with highly eccentric orbits, often referred to as the
‘last major merger.’ Hypotheses for the origin of this component include Gaia-Sausage/Enceladus (GSE), where the progenitor
collided with the MW proto-disc 8–11 Gyr ago, and the Virgo Radial Merger (VRM), where the progenitor collided with the
MW disc within the last 3 Gyr. These two scenarios make different predictions about observable structure in local phase space,
because the morphology of debris depends on how long it has had to phase mix. The recently identified phase-space folds in Gaia
DR3 have positive caustic velocities, making them fundamentally different than the phase-mixed chevrons found in simulations
at late times. Roughly 20 per cent of the stars in the prograde local stellar halo are associated with the observed caustics. Based
on a simple phase-mixing model, the observed number of caustics are consistent with a merger that occurred 1–2 Gyr ago.
We also compare the observed phase-space distribution to FIRE-2 Latte simulations of GSE-like mergers, using a quantitative
measurement of phase mixing (2D causticality). The observed local phase-space distribution best matches the simulated data
1–2 Gyr after collision, and certainly not later than 3 Gyr. This is further evidence that the progenitor of the ‘last major merger’
did not collide with the MW proto-disc at early times, as is thought for the GSE, but instead collided with the MW disc within
the last few Gyr, consistent with the body of work surrounding the VRM.
Current Ms word generated power point presentation covers major details about the micronuclei test. It's significance and assays to conduct it. It is used to detect the micronuclei formation inside the cells of nearly every multicellular organism. It's formation takes place during chromosomal sepration at metaphase.
When I was asked to give a companion lecture in support of ‘The Philosophy of Science’ (https://shorturl.at/4pUXz) I decided not to walk through the detail of the many methodologies in order of use. Instead, I chose to employ a long standing, and ongoing, scientific development as an exemplar. And so, I chose the ever evolving story of Thermodynamics as a scientific investigation at its best.
Conducted over a period of >200 years, Thermodynamics R&D, and application, benefitted from the highest levels of professionalism, collaboration, and technical thoroughness. New layers of application, methodology, and practice were made possible by the progressive advance of technology. In turn, this has seen measurement and modelling accuracy continually improved at a micro and macro level.
Perhaps most importantly, Thermodynamics rapidly became a primary tool in the advance of applied science/engineering/technology, spanning micro-tech, to aerospace and cosmology. I can think of no better a story to illustrate the breadth of scientific methodologies and applications at their best.
ESPP presentation to EU Waste Water Network, 4th June 2024 “EU policies driving nutrient removal and recycling
and the revised UWWTD (Urban Waste Water Treatment Directive)”
Deep Behavioral Phenotyping in Systems Neuroscience for Functional Atlasing a...Ana Luísa Pinho
Functional Magnetic Resonance Imaging (fMRI) provides means to characterize brain activations in response to behavior. However, cognitive neuroscience has been limited to group-level effects referring to the performance of specific tasks. To obtain the functional profile of elementary cognitive mechanisms, the combination of brain responses to many tasks is required. Yet, to date, both structural atlases and parcellation-based activations do not fully account for cognitive function and still present several limitations. Further, they do not adapt overall to individual characteristics. In this talk, I will give an account of deep-behavioral phenotyping strategies, namely data-driven methods in large task-fMRI datasets, to optimize functional brain-data collection and improve inference of effects-of-interest related to mental processes. Key to this approach is the employment of fast multi-functional paradigms rich on features that can be well parametrized and, consequently, facilitate the creation of psycho-physiological constructs to be modelled with imaging data. Particular emphasis will be given to music stimuli when studying high-order cognitive mechanisms, due to their ecological nature and quality to enable complex behavior compounded by discrete entities. I will also discuss how deep-behavioral phenotyping and individualized models applied to neuroimaging data can better account for the subject-specific organization of domain-general cognitive systems in the human brain. Finally, the accumulation of functional brain signatures brings the possibility to clarify relationships among tasks and create a univocal link between brain systems and mental functions through: (1) the development of ontologies proposing an organization of cognitive processes; and (2) brain-network taxonomies describing functional specialization. To this end, tools to improve commensurability in cognitive science are necessary, such as public repositories, ontology-based platforms and automated meta-analysis tools. I will thus discuss some brain-atlasing resources currently under development, and their applicability in cognitive as well as clinical neuroscience.
Or: Beyond linear.
Abstract: Equivariant neural networks are neural networks that incorporate symmetries. The nonlinear activation functions in these networks result in interesting nonlinear equivariant maps between simple representations, and motivate the key player of this talk: piecewise linear representation theory.
Disclaimer: No one is perfect, so please mind that there might be mistakes and typos.
dtubbenhauer@gmail.com
Corrected slides: dtubbenhauer.com/talks.html
3. Introduction:
Discovery of Nucleus by Ernest Rutherford ( 1871-1937)
Nucleus theory given in 1910, An atom’s mass is mostly in the nucleus and
it has a positive charge.
Prominent and Characteristics Features
Eukaryon means True nucleus
Basis of eukaryote- membrane bounded nucleus
Imp function: -Physically separates DNA from the cytoplasm’s complex
metabolic machinery
- Nuclear membrane serve as boundry
4. Definition:
The nucleus is the genetic control centre of a eukaryotic
cell.
In most cells, there is only one nucleus. It is spherical, and
the most prominent part of the cell, making up 10% of the
cell’s volume.
It has a unique structure and function that is essential for
the cell.
5. Components of Nucleus:
• 1. Nuclear Envelope – pore riddled
• 2. Nucleoplasm – Fluid interior portion
• 3. Nucleolus – Dense cluster of RNA &
Proteins
• 4. Chromatin – all DNA+ Proteins
Average diameter of nucleus is 6 µm,
which occupies around 10% of cell
volume.
7. Nuclear Membrane:
Also known as nuclear envelope or nucleolemma.
Separates the nuclear material from cytoplasm.
Consists of two lipid bilayers: Outer membrane, Inner
membrane
The nuclear envelope is a double-layered membrane
perforated with pores, which control the flow of
material going in and out of the nucleus. The outer
layer is connected to the endoplasmic reticulum,
communicating with the cytoplasm of the cell. The
exchange of the large molecules (protein and RNA)
between the nucleus and cytoplasm happens here.
8. Function Of Nuclear Membrane:
Shape and Stability: Helps the Nucleus From Collapsing
Compartmentalizing: Separates The Nuclear Material From
Cellular Material
Regulation Of Substances: Allow The Exchange Of Materials
Communication: Develops A Chemical Connection Between
Nucleus And Cell
9. The Nuclear Pore:
Most distinctive feature of NE
Small cylindrical channels- direct contact cytosol
& Nucleoplasm
Readily visible – freeze fracture microscopy (a
specimen is frozen rapidly and cracked on a plane
through the tissue)
Mammalian nucleus – 3000 to 4000 pores
Inner & outer membranes fused
Structural complexity – control transport of key
molecules
10. Function Of Nuclear Pore:
Exchange of materials between nucleus and cytoplasm
Passive diffusion of low molecular weight solutes
Efficient passage through the complex it requires
several protein factors.
11. Nucleoplasm:
A jelly-like (made mostly of water) matrix within the nucleus
Just like the cytoplasm found inside a cell, the nucleus contains nucleoplasm,
also known as karyoplasm
All the other materials “float” inside
Helps the nucleus keep its shape and serves as the median for the transportation
of important molecules within the nucleus
The nucleoplasm is a type of protoplasm that is made up mostly of water, a
mixture of various molecules, and dissolved ions
It is completely enclosed within the nuclear membrane or nuclear envelope
12. Nucleolus:
Ribosome factory
Large, prominent structures
Doesn’t have membrane
Most cells have 2 or more
Directs synthesis of RNA
The nucleolus takes up around 25% of the volume of the nucleus.
This structure is made up of proteins and ribonucleic acids (rna). Its
main function is to synthesis ribosomal RNA(rrna) and combine it
with proteins.
13. Function of nucleolus:
Site for transcription ( cell makes RNA copy from
fragment of DNA)
Association of ribosomes
Synthesis of ribosomes
Synthesis of RNA
14. Chromosome:
Chromosome means: (chroma - colour, some - body)
A chromosome is a thread-like self-replicating genetic structure containing
organized DNA molecule package found in the nucleus of the cell.
Chromosomes are seen during metaphase stage of mitosis when the cells are
stained with suitable basic dye and viewed under light microscope.
E. Strasburger in 1875 discovered thread-like structures which appeared during
cell division.
In all types of higher organisms (eukaryote), the well organized nucleus contains
definite number of chromosomes of definite size and shape.
15. H. G. Waldeyer coined the term chromosome first time in 1888.
The somatic chromosome number is the number of chromosomes
found in somatic cell and is represented by 2n (Diploid).
The gametic chromosome number is half of the somatic
chromosome numbers and represented by n (Haploid).
The two copies of chromosome are ordinarily identical in
morphology, gene content and gene order, they are known as
homologous chromosomes.
16. Chromosomes are of two types:
Autosomes: that control characters other than sex characters or carry
genes for somatic characters.
Sex chromosomes (Gonosomes): Chromosomes involved in sex
determination.
Humans and most other mammals have two sex chromosomes X &
Y, also called heterosome.
Females have two X chromosomes in diploid cells; males have an X
and a Y chromosome.
In birds the female (ZW) is hetero-gametic and male (ZZ) is homo-
gametic.
17. The size of chromosome is normally measured at mitotic metaphase
and may be as short as 0.25 µm in fungi and birds, or as long as 30
µm in some plants like Trillium.
Each chromosome has two arms - p (the shorter of the two) and q
(the longer).
Chromosome shape is usually observed at anaphase, when the
position of primary constriction (centromere) determines chromosome
shape.
This constriction or centromere can be terminal, sub-terminal or
median in position.
19. Chromosome Morphology:
Mitotic metaphase is the most suitable stage for studies on
chromosome morphology.
The chromosome morphology changes during cell division.
Chromosomes are thin, coiled, elastic, thread-like structures during
the interphase.
As cells enter mitosis, their chromosomes become highly condensed
so that they can be distributed to daughter cells.
In mitotic metaphase chromosomes, the following structural features
can be seen under
20. Chromatid:
Each metaphase chromosome appears to be longitudinally divided into two
identical parts each of which is called chromatid.
Both the chromatids of a chromosome appear to be joined together at a point
known as centromere.
The two chromatids of chromosome separate from each other during mitotic
anaphase (and during anaphase II of meiosis) and move towards opposite poles.
Since the two chromatids making up a chromosome are produced through
replication of a single chromatid during synthesis (S) phase of interphase, they
are referred to as sister chromatids.
In contrast, the chromatids of homologous chromosomes are known as non-
sister chromatids.
21. Two types of chromatids
1) Euchromatin which undergoes the normal process of condensation and
decondensation in the cell cycle.
2) Heteochromatin which remain in a highly condensed state throughout the
cell, even during interphase.
Chemical composition of chromatid :
DNA= 20-40 %- most important chemical constituent of chromatin.
RNA=05-10 %-associated with chromatin as; Ribosomal RNA-( rRNA)
Messenger RNA- (mRNA) Transfer RNA- (tRNA).
PROTEINS=55-60%-associated with chromatin as,
I. Histones : - Very basic proteins +ve charged at neutral PH, constitute about 60%
of total protein, almost 1:1 ratio with DNA.
II. Non-Histones : - They are 20% of total chromatin protein
22.
23. Centromere (Primary constriction)
• Centromere is the landmark for identification of chromosome.
• Each chromosome has a constriction point called the centromere (Synonym:
Kinetochore), which divides the chromosome into two sections or arms.
• The short arm of the chromosome is labeled the "p" arm. The long arm of the
chromosome is labeled the "q" arm.
Telomere
• The two ends of a chromosome are known as telomeres, they play critical roles
in chromosome replication and maintenance of chromosomal length.
• The telomeres are highly stable and telomeres of different chromosomes do not
fuse.
• The telomeric region of chromosome is made up of repetative sequence of T and
G bases.
24. Secondary constriction
• In some chromosome addition to centromere / primary
constriction, one or more constrictions in the chromosome are
present termed secondary constrictions.
Satellite
• The chromosomal region between the secondary constriction and
nearest telomere is called as satellite and chromosomes that
possess this region called as satellite chromosome or sat
chromosome.
• A small chromosomal segment separated from the main body of
the chromosome by a secondary constriction is called Satellite.
25. Size of the chromosome:
• The size of the chromosome varies from stage to stage of cell
division.
• The chromosomes are the longest and thinnest during interphase
(resting stage) and hence not visible under light microscope.
• Chromosomes are the smallest and thickest during mitotic
metaphase.
• Chromosome size is not proportional to the number of genes
present on the chromosome.
• The location of the centromere on each chromosome gives the
chromosome its characteristic shape.
26. Types of chromosome based on
centromere:
Metacentric chromosome:
The centromere is located in the centre of chromosomes, i.e. the
centromere is median. The centromere is localized approximately
midway between each end and thereby two arms are roughly equal
in length.
Metacentric chromosome take V shape during anaphase.
27. Submetacentric Chromosome
Centromere is located on one side of the central point of a chromosome.
Centromere is sub median giving one longer and one shorter arms.
Submetacentric chromosome may be J or L shaped during anaphase.
Acrocentric Chromosome
The centromere located close to one end of chromosomes. The
centromere is more terminally placed and forms very unequal arm length
(The "acro-" in acrocentric refers to the Greek word for "peak").
The p (short) arm is so short that is hard to observe, but still present.
Acrocentric chromosome may be rod shape during anaphase.
28. Telocentric Chromosome
Centromere located at one end of chromosome (at terminal part of
chromosome) lies at one end.
Telocentric chromosome may be rod shape during anaphase.
According to the number of the centromere the eukaryotic chromosomes
may be:
Acentric: without any centromere
Mono centric: with one centromere
Dicentric : with two centromeres
Polycentric: with more than two centromeres
29.
30. Special type of chromosome:
1. Giant chromosomes: These were first discovered by E. G. Balbiani in 1882. They are made
up of several dark staining regions called “bands”.
It can be separated by relatively light or non-staining “interband” regions.
The bands in Drosophila giant chromosome are visible even without staining, but after
staining they become very sharp and clear.
These chromosomes are also known as “Polytene chromosome”, and the condition is
referred to as “Polytene”
2. Lampbrush Chromosome: These were first observed by W. Flemming in 1882. It was
given this name because it is similar in appearance to the brushes used to clean lamp
chimneys in centuries past.
These are found in oocytic nuclei of vertebrates (sharks, amphibians, reptiles and
birds)as well as in invertebrates (Sagitta, sepia, Ehinaster and several species of
insects).
31. 3. Accessory chromosomes:- In many species some chromosomes are
found in addition to normal somatic chromosomes.
These extra chromosomes are called accessory chromosomes or B-
chromosomes or supernumerary chromosomes.
These chromosomes are broadly similar to normal somatic chromosomes
in their morphology
For instance, presence of several such chromosomes often leads to
reduction in vigour and fertility in males. Origin of these chromosomes in
most species is unknown.
4. Isochromosomes:- An isochromosome is the one in which two arms are
identical with each other in gene content and morphology.
Every isochromosome is metacentric. The attached ‘x’ chromosome of
Drosophila is a classical example of an isochromosome. However its
origin is uncertain.
32. 5. Allosomes / sex chromosomes:- Chromosomes differing in
morphology and number in male and female are called allosomes.
They are responsible for determination of sex.
eg: X and Y chromosomes in human beings and Drosophila.
Chromosomes which have no relation with determination of sex and
contain genes which determine somatic characters of individuals are
called autosomes and are represented by letter ‘A’.
33. Variation in chromosome number:
Organism with one complete set of chromosomes is said to be
euploid (applies to haploid and diploid organisms).
Aneuploidy - variation in the number of individual chromosomes
(but not the total number of sets of chromosomes).
The discovery of aneuploidy dates back to 1916 when Bridges
discovered XO male and XXY female Drosophila, which had 7
and 9 chromosomes respectively, instead of normal 8.
34. Nullisomy - loss of one homologous chromosome pair.
(e.g., Oat )
Monosomy - loss of a single chromosome (Maize).
Trisomy - one extra chromosome. (Datura)
Tetrasomy - one extra chromosome pair.
35. Chromosomal Aberrations:
The somatic (2n) and gametic (n) chromosome numbers of a
species ordinarily remain constant.
This is due to the extremely precise mitotic and meiotic cell
division.
Somatic cells of a diploid species contain two copies of each
chromosome, which are called homologous chromosome.
Each chromosome of a genome contains a definite numbers and
kinds of genes, which are arranged in a definite sequence.
36. Sometime due to mutation or spontaneous (without any known
causal factors), variation in chromosomal number or structure do
arise in nature. - Chromosomal aberrations.
Chromosomal aberration may be grouped into two broad classes:
1. Structural
2. Numerical
37. Structural Chromosomal Aberrations:
Chromosome structure variations result from chromosome breakage.
Broken chromosomes tend to re-join; if there is more than one break, re-
joining occurs at random and not necessarily with the correct ends.
The result is structural changes in the chromosomes.
Chromosome breakage is caused by X-rays, various chemicals, and can also
occur spontaneously.
There are four common type of structural aberrations:
1. Deletion or Deficiency
2. Duplication or Repeat
3. Inversion
4. Translocation.
38. Consider a normal chromosome with genes in alphabetical order: a b c d
e f g h i
1. Deletion: part of the chromosome has been removed:
a b c g h i
2. Dupliction: part of the chromosome is duplicated:
a b c d e f d e f g h i
3. Inversion: part of the chromosome has been re-inserted in reverse order:
a b c f e d g h i
4. Translocation: parts of two non-homologous chromosomes are joined:
If one normal chromosome is a b c d e f g h i and the other chromosome is
u v w x y z, then a translocation between them would be
a b c d e f x y z and u v w g h i.
39. A New Chromosome Model
• Chromosomes and their function have been well known for more than 100
years. The three-dimensional architecture of chromosomes however, still a
matter of intense discussion.
• In general, metaphase chromosomes consist of the following elements: A pair
of two chromosome arms of either equal or unequal length which splits into
two chromatides during metaphase.
• There is one obligatory constriction which defines the “centromere” and a
facultative constriction which represents the “satellite region.” The
chromatides are terminated by telomeres.
G. Wanner and H. Formanek
August 22, 2000
Munich, Germany
Case study: 1
40. •The structural compound of chromosomes, the chromatin,
consists of equal amounts of DNA, histones and
nonhistone proteins (Earnshaw, 1991).
• Chromatin consists of “euchromatin,” which condenses
(and stains intensely) during mitosis, and
“heterochromatin,” which remains condensed during
interphase also (Passarge, 1979; Traut, 1991a).
41. Methodology:
• Human and plant chromosomes were prepared for high-resolution scanning
electron microscopy as described (Martin et al., 1994, 1996).
• Controlled decondensation of (unfixed) metaphase chromosomes was achieved
by treatment with citrate buffer (60 mM, pH 7.2) for 60 min at room temperature.
• For proteinase treatment chromosomes were first fixed with glutaraldehyde
(2.5% in 75 mM cacodylate buffer) and then treated with proteinase K (0.1–1
mg/ml) for 30 min at 37°C.
• For separate visualization of DNA, chromosomes were stained for 30 min at
20°C with 1% zirconiumchloridoxide in 1% hydrochloric acid.
42. • Proteins were separately visualized after staining for 12 h at 60°C with 20%
aqueous silver nitrate solution.
• The colloidal silver solution was prepared in the following way: 0.5 g silver nitrate
dissolved in 1.5 ml water was slowly added to 25 ml of an aqueous solution of
0.25% tannic acid and 2% sodium carbonate by continuous stirring at room
temperature.
• A slight precipitate forms within 24 h which is removed by centrifugation (Lea,
1891; Gmelin, 1971). After the specimens were washed with aqua dest. (three
times for 5 min at 2°C) they were dehydrated through a graded acetone series (20–
100%) and critical point dried with liquid CO2. Chromosome spreads were
preselected with a light microscope.
43. Result
• From their investigations it is obvious that there are two dominant
structural elements in metaphase chromosomes: coiled chromomeres
and parallel matrix fibers.
• Since 1929 these heterochromatic structures have been called
“chromomeres” During metaphase they can be observed only (if at
all) in the centromeric and satellite regions. They become visible best
after controlled decondensation of metaphase chromosomes by
proteinase K treatment.
44. •According to our ultrastructural investigations, they
propose a new model for the three-dimensional structure
of chromosomes.
•The model can simply explain the enormous variety of
chromosome morphology in plant and animal systems by
varying only a few cytological parameters.
45. The Structure of the Nucleus Studied by Electron
Microscopy in Ultrathin Sections with Special
Reference to the Chromonema-An Advocation of
"Subchromonema" and "Protochromonema"
• The nucleus was the first intracellular structure discovered and
was originally described by Franz Bauer in 1802 and later
popularized by Robert Brown.
• The purpose of study to obtain a precise knowledge concerning the
structure of the nucleus, especially (a) the finest structure of the
chromosome, (b) the chromosomal constrictions and (c) various
nucleolar structures found in resting nuclei.
Kyoto, Japan Shigeyasu Amano et. al
March 30, 1956
Case study: 2
46. Methodology:
• Plasma cells, monocytes and lymphocytes in mice were utilized in
this study. Referring to the procedure to get ultrathin sections and
electron microphotographs. (Dohi, 1955)
Observations:
• Chromonema and subchromonema in the nucleus of plasma cell
• Chromosome, chromonema and subchromonema in the mitotic
nucleus of lymphocyte
• Chromonema and subchromonema in the resting nuclei of
lymphocytes.
47. Result:
• In their previous phase microscope studies, various interkinetic nuclei were
described, in which the chromonema structure is either (a) uncoiled completely.
The cells belonging to the latter group (b) such as lymphocytes, monocytes and
plasma cells in mice, referring especially to their chromonema structure as seen in
ultrathin section by an electron microscope.
• The proto chromonemata (coiled chromatin thread within a single chromosome)
belong to the morphological limit capable of being observed by an electron
microscope in ultrathin sections.
• observation was confirmed also with a structure of the more or less loosely coiled
chromosomes found in mitotic lymphocytes in prophase.
• The size and structure of the chromonema and subchromonema in mitotic and
interkinetic stages were studied.
48. Reference:
Genome 4 by T. A. Brown
Life Science (Fundamental and practice) by Pranav Kumar and
Usha meena
B D Singh