1. Chromosomes contain the genetic material DNA and protect it during cell division. The structure of chromosomes allows for precise distribution of DNA to daughter cells.
2. Gene expression in eukaryotes is regulated by proteins associated with chromosomes. Chromatin fibers containing nucleosomes coil to form chromosomes.
3. Special chromosomes like lampbrush and giant chromosomes are found in some tissues. Lampbrush chromosomes facilitate gene transcription in oocytes. Giant chromosomes result from repeated DNA replication and form long polytene chromosomes used for gene expression.
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.
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 rod-shaped structures found in the nucleus of eukaryotic cells that are made of DNA coiled around proteins called histones. Each chromosome contains two identical halves called chromatids that are attached at the centromere. Chromatids are formed before cell division as DNA replicates to make a copy. When the cell divides, each new cell receives one chromatid from each chromosome. DNA is more loosely coiled as chromatin when not dividing and not tightly condensed into chromosomes.
1. Viral genomes contain DNA or RNA and are packaged into capsids through assembly processes. Bacterial chromosomes contain genes and other sequences compacted by looping and supercoiling.
2. Eukaryotic chromosomes vary greatly in size and contain genes and other sequences. Their DNA must be highly compacted to fit in the nucleus.
3. Eukaryotic DNA wraps around histone proteins to form nucleosomes, which further compact to form chromatin fibers and loop domains anchored to the nuclear matrix. Additional compaction occurs during cell division through condensin and cohesin proteins.
Chromosomes are structures within cell nuclei that carry genetic information. They are most visible during cell division. A chromosome has a centromere region that attaches to spindle fibers and allows proper separation of chromosomes during cell division. Chromosomes also have telomeres at the ends that are important for stability and replication. The number and structure of chromosomes can vary between species and abnormalities in chromosome number or structure are known as chromosomal aberrations, including deletions, duplications, inversions, and translocations.
Chromosomes are thread-like structures found within the nucleus of cells that carry genetic information. They are composed of DNA and proteins, and are only visible during cell division. Chromosomes contain genes and act as the primary physical basis for heredity by passing genetic traits from parents to offspring. The number and appearance of chromosomes are typically constant for each species. In humans, there are 23 pairs of chromosomes, for a total of 46.
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.
Chromosomes are structures that carry genetic material in the form of DNA. They play an important role in heredity, variation, evolution, and mutation. Each species has a characteristic number of chromosomes and features like size, centromere position, and banding patterns that make up its unique karyotype. Chromosomes are made up of DNA, proteins, and RNA and can replicate to pass genetic information between generations. They condense and compact DNA through structures like nucleosomes and chromatin to package it efficiently inside cells.
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.
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 rod-shaped structures found in the nucleus of eukaryotic cells that are made of DNA coiled around proteins called histones. Each chromosome contains two identical halves called chromatids that are attached at the centromere. Chromatids are formed before cell division as DNA replicates to make a copy. When the cell divides, each new cell receives one chromatid from each chromosome. DNA is more loosely coiled as chromatin when not dividing and not tightly condensed into chromosomes.
1. Viral genomes contain DNA or RNA and are packaged into capsids through assembly processes. Bacterial chromosomes contain genes and other sequences compacted by looping and supercoiling.
2. Eukaryotic chromosomes vary greatly in size and contain genes and other sequences. Their DNA must be highly compacted to fit in the nucleus.
3. Eukaryotic DNA wraps around histone proteins to form nucleosomes, which further compact to form chromatin fibers and loop domains anchored to the nuclear matrix. Additional compaction occurs during cell division through condensin and cohesin proteins.
Chromosomes are structures within cell nuclei that carry genetic information. They are most visible during cell division. A chromosome has a centromere region that attaches to spindle fibers and allows proper separation of chromosomes during cell division. Chromosomes also have telomeres at the ends that are important for stability and replication. The number and structure of chromosomes can vary between species and abnormalities in chromosome number or structure are known as chromosomal aberrations, including deletions, duplications, inversions, and translocations.
Chromosomes are thread-like structures found within the nucleus of cells that carry genetic information. They are composed of DNA and proteins, and are only visible during cell division. Chromosomes contain genes and act as the primary physical basis for heredity by passing genetic traits from parents to offspring. The number and appearance of chromosomes are typically constant for each species. In humans, there are 23 pairs of chromosomes, for a total of 46.
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.
Chromosomes are structures that carry genetic material in the form of DNA. They play an important role in heredity, variation, evolution, and mutation. Each species has a characteristic number of chromosomes and features like size, centromere position, and banding patterns that make up its unique karyotype. Chromosomes are made up of DNA, proteins, and RNA and can replicate to pass genetic information between generations. They condense and compact DNA through structures like nucleosomes and chromatin to package it efficiently inside cells.
It is a powerpoint presentation that discusses about the lesson or topic: Chromosomes. It also talks about the definition, history and the concepts about Chromosomes
The topic explains briefly on central dogma of molecular biology, DNA packaging in chromosome, to understanding the nature of genetics Code and to compare the mitochondria & chloroplast DNA with nuclear DNA
Chromosomes are structures that package and organize DNA and associated proteins. In eukaryotes, DNA is wrapped around histone proteins to form chromatin, which condenses into linear or circular chromosomes. Key features of eukaryotic chromosomes include centromeres, telomeres, and repetitive sequences. Chromosomes are compacted through DNA supercoiling and packaging into nucleosomes. The structure and packaging of chromosomes allows for efficient storage and regulation of the genetic material.
Lampbrush chromosome,chromosomes structure.giant chromosomes lambrush chromos...Anand P P
this slide mainly deals with the special types of chromosomes .normally the large sized chromosomes is called as the giant chromosomes,it occur in some insects larval stage .it has several functions and structural modifications.
The document summarizes the organization and structure of DNA within chromosomes. It discusses how DNA is packaged at different levels, from winding around histones to form nucleosomes, to coiling to form the 30nm chromatin fiber and further condensing to form mitotic chromosomes. It also describes the centromeres and telomeres, which play important roles in chromosome segregation and stability. Chromosomal banding patterns allow distinguishing each chromosome.
Chromosomes structure and function, Dr.Kamelsh shah, PSSHDA, KADI Dr.Kamlesh shah
Chromosomes have a complex hierarchical structure that allows long DNA molecules to fit inside cells. At the most basic level, DNA wraps around histone proteins to form nucleosomes, which resemble "beads on a string". Nucleosomes further compact to form higher-order chromatin structures. Chromatin contains both euchromatin, which is loosely packed, and heterochromatin, which is highly condensed. Non-histone proteins also aid in DNA compaction and genetic processes like transcription and replication. Chromatin packaging allows meters of DNA to fit within microscopic nuclei.
Rajeshwari pharm D .....chromatin: chromatin is a mass of genetic material......Types of chromatin
1.EUCHROMATIN
2.HETEROCHROMATIN
FUNCTIONS OF CHROMATIN: to compress the dna into compact form....flow of genetic information.
The document summarizes yeast chromosome structure and function. It discusses how DNA is packaged into chromatin and nucleosomes in yeast. The yeast genome contains 16 chromosomes with centromeres and telomeres. Histones can be post-translationally modified through acetylation, deacetylation, and methylation, which impacts chromatin structure and gene expression. Centromeres, origins of replication, and telomeres are also described.
This document provides an overview of chromosome structure and DNA packaging. It discusses how DNA is condensed and organized within the nucleus. DNA wraps around histone proteins to form nucleosomes, which further coil to form 30nm fibers and loop domains. This allows the long DNA molecules to tightly pack into chromosomes. Chromosomes condense further during cell division and can be seen under a microscope. Each chromosome contains a centromere and telomeres that help organize and protect the DNA.
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.
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.
DNA is highly compacted in cells through various levels of supercoiling and chromatin structure. At the most basic level, DNA wraps around histone proteins to form nucleosomes, introducing negative supercoiling. Nucleosomes are then packed into a beads-on-a-string structure and further compacted into the 30nm fiber. Additional folding compacts the DNA over 10,000-fold into the final chromosomes. The two main types of supercoiling that facilitate compaction are plectonemic and solenoidal, with solenoidal supercoiling allowing the greatest degree of compaction and found in chromatin.
Chromatin is composed of DNA wrapped around histone proteins, which allows it to be tightly packed in the cell nucleus. There are two main types of chromatin: euchromatin, which is loosely coiled and allows for transcription; and heterochromatin, which is tightly packed and generally not transcribed. DNA combines with histone proteins to form nucleosomes, which involve 146bp of DNA wrapped around an octamer of core histone proteins. Nucleosomes further fold into a 30nm fiber, which then loops and coils to allow the long DNA molecules to fit inside the cell nucleus.
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.
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.
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 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.
Centromere and the kinectochore function and structureAfrozzay Afrozzay
The centromere is a region of DNA responsible for the movement of chromosomes during cell division. It ensures each daughter cell receives one copy of each chromosome. The kinetochore is a protein structure assembled at each centromere that attaches to spindle microtubules and generates force to power chromosome movement. It also signals the mitotic checkpoint to delay cell division until all kinetochores are properly attached. The centromere functions to join sister chromatids and attach kinetochores to the mitotic spindle through microtubules so chromosomes are accurately segregated into daughter cells during cell division.
Eukaryotic genomes are organized into chromatin and packaged at successive levels. DNA is wrapped around histone proteins to form nucleosomes, which are further packaged into higher-order structures like the 30nm fiber and loop domains. These domains are attached to scaffolding proteins, forming interphase chromosome territories and mitotic chromosomes. Precise packaging allows for gene expression control and proper chromosome segregation during cell division. Telomeres and histone modifications also influence chromatin structure and gene regulation.
It is a powerpoint presentation that discusses about the lesson or topic: Chromosomes. It also talks about the definition, history and the concepts about Chromosomes
The topic explains briefly on central dogma of molecular biology, DNA packaging in chromosome, to understanding the nature of genetics Code and to compare the mitochondria & chloroplast DNA with nuclear DNA
Chromosomes are structures that package and organize DNA and associated proteins. In eukaryotes, DNA is wrapped around histone proteins to form chromatin, which condenses into linear or circular chromosomes. Key features of eukaryotic chromosomes include centromeres, telomeres, and repetitive sequences. Chromosomes are compacted through DNA supercoiling and packaging into nucleosomes. The structure and packaging of chromosomes allows for efficient storage and regulation of the genetic material.
Lampbrush chromosome,chromosomes structure.giant chromosomes lambrush chromos...Anand P P
this slide mainly deals with the special types of chromosomes .normally the large sized chromosomes is called as the giant chromosomes,it occur in some insects larval stage .it has several functions and structural modifications.
The document summarizes the organization and structure of DNA within chromosomes. It discusses how DNA is packaged at different levels, from winding around histones to form nucleosomes, to coiling to form the 30nm chromatin fiber and further condensing to form mitotic chromosomes. It also describes the centromeres and telomeres, which play important roles in chromosome segregation and stability. Chromosomal banding patterns allow distinguishing each chromosome.
Chromosomes structure and function, Dr.Kamelsh shah, PSSHDA, KADI Dr.Kamlesh shah
Chromosomes have a complex hierarchical structure that allows long DNA molecules to fit inside cells. At the most basic level, DNA wraps around histone proteins to form nucleosomes, which resemble "beads on a string". Nucleosomes further compact to form higher-order chromatin structures. Chromatin contains both euchromatin, which is loosely packed, and heterochromatin, which is highly condensed. Non-histone proteins also aid in DNA compaction and genetic processes like transcription and replication. Chromatin packaging allows meters of DNA to fit within microscopic nuclei.
Rajeshwari pharm D .....chromatin: chromatin is a mass of genetic material......Types of chromatin
1.EUCHROMATIN
2.HETEROCHROMATIN
FUNCTIONS OF CHROMATIN: to compress the dna into compact form....flow of genetic information.
The document summarizes yeast chromosome structure and function. It discusses how DNA is packaged into chromatin and nucleosomes in yeast. The yeast genome contains 16 chromosomes with centromeres and telomeres. Histones can be post-translationally modified through acetylation, deacetylation, and methylation, which impacts chromatin structure and gene expression. Centromeres, origins of replication, and telomeres are also described.
This document provides an overview of chromosome structure and DNA packaging. It discusses how DNA is condensed and organized within the nucleus. DNA wraps around histone proteins to form nucleosomes, which further coil to form 30nm fibers and loop domains. This allows the long DNA molecules to tightly pack into chromosomes. Chromosomes condense further during cell division and can be seen under a microscope. Each chromosome contains a centromere and telomeres that help organize and protect the DNA.
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.
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.
DNA is highly compacted in cells through various levels of supercoiling and chromatin structure. At the most basic level, DNA wraps around histone proteins to form nucleosomes, introducing negative supercoiling. Nucleosomes are then packed into a beads-on-a-string structure and further compacted into the 30nm fiber. Additional folding compacts the DNA over 10,000-fold into the final chromosomes. The two main types of supercoiling that facilitate compaction are plectonemic and solenoidal, with solenoidal supercoiling allowing the greatest degree of compaction and found in chromatin.
Chromatin is composed of DNA wrapped around histone proteins, which allows it to be tightly packed in the cell nucleus. There are two main types of chromatin: euchromatin, which is loosely coiled and allows for transcription; and heterochromatin, which is tightly packed and generally not transcribed. DNA combines with histone proteins to form nucleosomes, which involve 146bp of DNA wrapped around an octamer of core histone proteins. Nucleosomes further fold into a 30nm fiber, which then loops and coils to allow the long DNA molecules to fit inside the cell nucleus.
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.
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.
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 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.
Centromere and the kinectochore function and structureAfrozzay Afrozzay
The centromere is a region of DNA responsible for the movement of chromosomes during cell division. It ensures each daughter cell receives one copy of each chromosome. The kinetochore is a protein structure assembled at each centromere that attaches to spindle microtubules and generates force to power chromosome movement. It also signals the mitotic checkpoint to delay cell division until all kinetochores are properly attached. The centromere functions to join sister chromatids and attach kinetochores to the mitotic spindle through microtubules so chromosomes are accurately segregated into daughter cells during cell division.
Eukaryotic genomes are organized into chromatin and packaged at successive levels. DNA is wrapped around histone proteins to form nucleosomes, which are further packaged into higher-order structures like the 30nm fiber and loop domains. These domains are attached to scaffolding proteins, forming interphase chromosome territories and mitotic chromosomes. Precise packaging allows for gene expression control and proper chromosome segregation during cell division. Telomeres and histone modifications also influence chromatin structure and gene regulation.
This document describes two models of chromosome structure:
1. The Dupraw (folded fiber) model, which proposes that DNA is wrapped around proteins to form fibers of increasing diameter and compaction up to the chromatid level.
2. The nucleosome model, which shows that chromatin is made up of repeating nucleosome units containing histones and 146 base pairs of DNA coiled around them. Nucleosomes are separated by linker DNA and can further condense into a solenoid and super solenoid structure.
This document summarizes key components and functions of the cell nucleus. It describes the nuclear envelope, nuclear pores, nucleolus, and chromatin. The nuclear envelope is a double membrane with pores that allow transport of molecules. The nucleolus is the site of ribosome biogenesis. Chromatin is made up of DNA and proteins like histones that package the DNA into nucleosomes and different levels of compaction. The document provides details on these nuclear structures and their roles in genetic material organization and molecular transport.
This document summarizes key components and functions of the cell nucleus. It describes the nuclear envelope, nuclear pores, nucleolus, and chromatin. The nuclear envelope is a double membrane with pores that allow transport of molecules. The nucleolus is the site of ribosome biogenesis. Chromatin is made up of DNA and proteins like histones that package the DNA into nucleosomes and different levels of compaction. The document provides details on these nuclear structures and their roles in genetic material organization and molecular transport.
This document describes Du Praw's model of chromatin structure. According to the model, each chromatin fiber contains a single DNA double helix that is coiled and coated with histone and non-histone proteins, forming a fiber about 230 angstroms in diameter. During cell division, the chromatin fibers fold and supercoil to form thicker chromosomes and reduce their length. Evidence from various studies supports that each chromatid contains a single giant DNA molecule.
This document provides information on the structure and organization of chromatin. It discusses three main levels of chromatin organization:
1) Nucleosomes, which involve DNA wrapping around histone proteins in "beads on a string" structures.
2) The 30nm chromatin fiber, where nucleosomes are further compacted into a solenoid structure through histone H1 binding.
3) Higher-order compaction into metaphase chromosomes, where DNA is organized into loops anchored to a protein scaffold.
The document also describes different chromatin types (euchromatin and heterochromatin), chromatin composition, and models of chromatin structure including the nucleosome model.
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.
Human DNA must be highly compressed to fit inside the nucleus. It achieves this by wrapping around proteins called nucleosomes, which act as spools. Each nucleosome contains an octamer of histone proteins around which 147 base pairs of DNA are wrapped. Multiple nucleosomes then coil further to form a 30nm fiber. This fiber is attached to a scaffold of RNA and proteins, forming loops that allow for further compaction of the DNA into chromosomes. The positioning of centromeres divides chromosomes into metacentric, submetacentric and acrocentric types in humans.
This document provides an overview of genome organization in viruses, prokaryotes, and eukaryotes. It discusses the differences between DNA and RNA, various structural forms of DNA, and levels of genome organization. In viruses, genomes can be single or double-stranded DNA or RNA, linear or circular, and range in size from 2,000 to 2,000,000 base pairs. Prokaryotic genomes are typically single, circular chromosomes that are organized via nucleoid formation, supercoiling, and DNA looping. Eukaryotic genomes are located in the nucleus and mitochondria, arranged in linear chromosomes via interactions with histone proteins to form nucleosomes, chromatin fibers, euchromatin, and heter
This is a comprehensive account of the structure of eukaryotic chromosomes. It deals with the morphology, formation, and types of chromosomes present in eukaryotic cells. The main point of interest is the folding and packaging of DNA and proteins to make chromatin.
The document discusses several key concepts related to DNA packaging and gene expression. It describes the central dogma where genetic information flows from DNA to RNA to proteins. It also discusses how DNA is packaged in cells through nucleosomes and chromatin, and how chromatin exists in two forms - euchromatin which is loosely packed and transcriptionally active, and heterochromatin which is tightly packed and transcriptionally inactive. It provides information on calculating DNA length and the number of base pairs.
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.
III year Pharm.D - Pharmacology -II - "Chromosome structure: Pro and eukaryotic chromosome
structures, chromatin structure, genome complexity, the flow of
genetic information"
The document discusses several key topics related to DNA structure and function:
DNA replication ensures each cell has an exact copy of the DNA before cell division. Errors are constantly checked and repaired to maintain high fidelity. DNA is also rearranged through processes like recombination. The tightly regulated enzymes that perform these metabolic processes were demonstrated by the Meselson-Stahl experiment to replicate DNA using a semiconservative mechanism. DNA is organized through various levels of compaction into condensed chromosomes. This dynamic structure, along with features like centromeres and telomeres, helps regulate DNA accessibility and proper segregation during cell division.
Polytene chromosomes are large chromosomes found in secretory cells like salivary glands that contain thousands of identical DNA strands aligned in parallel. This gives them a banded appearance with dark bands and clear interbands when viewed under a microscope. The bands represent regions of condensed and transcriptionally active DNA. B chromosomes are nonessential supernumerary chromosomes that are found in some populations but not others and can provide adaptive advantages in some species and environments.
Nucleus pdf download link hope it helps youmansidhingra05
The nucleus is the control center of the cell that contains the cell's genetic material (DNA). It maintains the integrity of genes and controls cell activities through regulating gene expression. The nucleus is enclosed by a nuclear envelope and contains chromatin, nucleoplasm, and nucleoli. It carries out functions like DNA replication, transcription, and ribosomal synthesis. The nuclear envelope separates the nucleoplasm from the cytoplasm and contains nuclear pores to transport molecules. Meiosis produces gametes through two cell divisions that reduce the chromosome number by half to generate genetic variation.
The nucleus is the control center of the cell that contains DNA. It maintains the integrity of genes and controls cell activities through regulating gene expression. The nucleus is enclosed by a nuclear envelope with nuclear pores that regulate molecular trafficking. Within the nucleus are chromatin, nucleolus, and nucleoplasm. The nucleolus forms ribosomes, chromatin contains DNA and proteins, and nucleoplasm scaffolds nuclear components. The nucleus ensures DNA replication, transcription, and transmission to new cells through the cell cycle and mitosis/meiosis.
THE SACRIFICE HOW PRO-PALESTINE PROTESTS STUDENTS ARE SACRIFICING TO CHANGE T...indexPub
The recent surge in pro-Palestine student activism has prompted significant responses from universities, ranging from negotiations and divestment commitments to increased transparency about investments in companies supporting the war on Gaza. This activism has led to the cessation of student encampments but also highlighted the substantial sacrifices made by students, including academic disruptions and personal risks. The primary drivers of these protests are poor university administration, lack of transparency, and inadequate communication between officials and students. This study examines the profound emotional, psychological, and professional impacts on students engaged in pro-Palestine protests, focusing on Generation Z's (Gen-Z) activism dynamics. This paper explores the significant sacrifices made by these students and even the professors supporting the pro-Palestine movement, with a focus on recent global movements. Through an in-depth analysis of printed and electronic media, the study examines the impacts of these sacrifices on the academic and personal lives of those involved. The paper highlights examples from various universities, demonstrating student activism's long-term and short-term effects, including disciplinary actions, social backlash, and career implications. The researchers also explore the broader implications of student sacrifices. The findings reveal that these sacrifices are driven by a profound commitment to justice and human rights, and are influenced by the increasing availability of information, peer interactions, and personal convictions. The study also discusses the broader implications of this activism, comparing it to historical precedents and assessing its potential to influence policy and public opinion. The emotional and psychological toll on student activists is significant, but their sense of purpose and community support mitigates some of these challenges. However, the researchers call for acknowledging the broader Impact of these sacrifices on the future global movement of FreePalestine.
Level 3 NCEA - NZ: A Nation In the Making 1872 - 1900 SML.pptHenry Hollis
The History of NZ 1870-1900.
Making of a Nation.
From the NZ Wars to Liberals,
Richard Seddon, George Grey,
Social Laboratory, New Zealand,
Confiscations, Kotahitanga, Kingitanga, Parliament, Suffrage, Repudiation, Economic Change, Agriculture, Gold Mining, Timber, Flax, Sheep, Dairying,
Philippine Edukasyong Pantahanan at Pangkabuhayan (EPP) CurriculumMJDuyan
(𝐓𝐋𝐄 𝟏𝟎𝟎) (𝐋𝐞𝐬𝐬𝐨𝐧 𝟏)-𝐏𝐫𝐞𝐥𝐢𝐦𝐬
𝐃𝐢𝐬𝐜𝐮𝐬𝐬 𝐭𝐡𝐞 𝐄𝐏𝐏 𝐂𝐮𝐫𝐫𝐢𝐜𝐮𝐥𝐮𝐦 𝐢𝐧 𝐭𝐡𝐞 𝐏𝐡𝐢𝐥𝐢𝐩𝐩𝐢𝐧𝐞𝐬:
- Understand the goals and objectives of the Edukasyong Pantahanan at Pangkabuhayan (EPP) curriculum, recognizing its importance in fostering practical life skills and values among students. Students will also be able to identify the key components and subjects covered, such as agriculture, home economics, industrial arts, and information and communication technology.
𝐄𝐱𝐩𝐥𝐚𝐢𝐧 𝐭𝐡𝐞 𝐍𝐚𝐭𝐮𝐫𝐞 𝐚𝐧𝐝 𝐒𝐜𝐨𝐩𝐞 𝐨𝐟 𝐚𝐧 𝐄𝐧𝐭𝐫𝐞𝐩𝐫𝐞𝐧𝐞𝐮𝐫:
-Define entrepreneurship, distinguishing it from general business activities by emphasizing its focus on innovation, risk-taking, and value creation. Students will describe the characteristics and traits of successful entrepreneurs, including their roles and responsibilities, and discuss the broader economic and social impacts of entrepreneurial activities on both local and global scales.
Andreas Schleicher presents PISA 2022 Volume III - Creative Thinking - 18 Jun...EduSkills OECD
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Genetics
1. Genetic control mechanism in
eukaryotes
Prepared by Ganga Ram Kohar
Assistant professor IAAS Paklihawa
2. Structure of chromosome
• One micron of a metaphase chromosome
contains about 800μ of DNA helix
• The structure of chromosome is different
according to different model given by
scientists
3. A. Typical early model
• This is one of he earliest model of chromosome
structure based on light microscope
• According to this model the basic component of
chromosome structure is chromonema which
composed of chromatin and contains genes
• The variation in chromosome length and
thickness is proposed to be due to coiling and
uncoiling of chromosome
• Each chromatid of a chromosome may contain
two or more chromonemata which run across
through centromere
4. Conti..
• In the case of meta phase chromosome
,chromosome are surrounded by an
amorphous matrix the outer side of which is
enclosed in the membrane call pellicle
• However ,electron micrographs of metaphase
chromosome do not show any evidence for
existence of either matrix or pellicle
• So ,this model of chromosome structure is
inadequate and of historical interest only
6. B. Recent modes of chromosome
1. Multistranded model
• According to this model , each chromatin fiber is
on an average 100Λ in diameter
• Each chromatin fiber is composed of two strands
• Each strand being 35-40 Λ in diameter
• Each strand consists of single DNA double helix (20
Λ in diameter) and the associated histone and non
histone protein ,thus a chromatin fiber contains
two DNA double helix (separated from each other
by a space of about 25 Λ) and associated protein
7. Conti..
• Four chromatin fibers(each composed of two DNA
double helix) coil around each other to from quarter
chromatid which is a smallest sub unit of the
chromosome visible under light microscope in many
organisms
• Association of two quarter chromatid (each of 400 Λ
diameter ) give rise to one half chromatids of 800 Λ
diameter ,which is composed of 16DNA double helix
• Finally ,two half chromatid coil around each other to
produce one chromatid which is 1600 Λ in diameter
and made up of 32 DNA double helix
8. Conti..
• Thus , a metaphase chromosome has 64DNA
double helix and strand would be about 3200
Λ in diameter
• The variation in chromosome thickness would
be due to coiling and uncoiling of chromatid
• The number of DNA double helices in quarter
,half and full chromatids are proposed to vary
from 8 to 64 depending upon species
10. 2. Folded fiber model
• This model was proposed by Du Praw in 1965 and is
widely accepted
• According to this model, chromosomes are made
of chromatin fibers of about 230A° diameter
• Each chromatin fiber contains only one DNA
double helix which is in a coiled state; this DNA coil
is coated with histone and non-histone proteins
• Thus the 230A° chromatin fiber is produced by
coiling of a single DNA double helix, the coils of
which are stabilized by proteins and divalent
cations (Ca++ and Mg++)
11. Conti…
• Each chromatid contains a single long chromatin
fibers; the DNA of this fiber replicates during
interphase producing two sister chromatin fibres, it
remains unreplicated in the centromeric region so
that the two sister fibres remain joined in the
region
• Subsequently, the chromatin fibre undergoes
replication in the centromeric region as well so
that the sister chromatin fibre are separated in this
region also
12. Conti…
• During cell division the two sister chromatin
fibres undergo extensive folding separately in an
irregular manner to give rise to two sister
chromatids
• Folding of the chromatin fibres drastically reduces
their length and increases their stainability and
thickness
• This folded structure normally undergoes
supercoiling which further increases the thickness
of chromosomes and reduces the length
13.
14. C. Organization of chromatin fibers
• Any model of chromatin fibre structure has to
account for
• (i) packaging of a very long DNA molecule into a
unit length of fibre
• (ii) production of very thick (230-300A0) fibres
from very thin (20A°) DNA molecules
• (iii) the beads-on-a-string ultrastructure of
chromatin fibres observed particularly during
replication
• Two clearly different models of chromatin fibre
structure have been proposed
15. I. Coiled DNA Model:
• This is the simplest model of chromatin fibre organization
and was given by Du Praw
• According to this model, the single DNA molecule of a
chromatin fiber is coiled in a manner similar to the wire in a
spring; the coils being held together by histone bridges pro-
duced by binding histone molecules in the large groove of
DNA molecules.
• Such a coiled structure that would be stabilized as a single
histone molecule would bind to several coils of DNA
• This coiled structure is coated with chromosomal proteins to
yield the basic structure of chromatin fibres (type A fibre)
which may undergo supercoiling to produce the type B fibre
of DuPraw which is akin to the beads seen in electron
micrographs of chromatin fibres
17. II. Nucleosome-Solenoid Model
• This model was proposed by Romberg and Thomas
(1974) and is the most widely accepted
• According to this model, chromatin is composed of a
repeating unit called nucleosome
• Nucleosomes are the fundamental packing unit par-
ticles of the chromatin and give chromatin a “beads-
on-a string” appearance in electron micrographs that
unfold higher-order packing (Olins and Olins, 1974).
• One complete nucleosome consists of a nucleosome
core, linker DNA, an average of one molecule of H1
histone and other associated chromosomal proteins
19. Nucleosome Core
• It consists of a histone octamer composed of
two molecules, each of histones H2a, H2b,H3
and H4. In addition, a 146 bp long DNA
molecule is wound round this histone octamer
in 13/4 turns; this segment of DNA is nuclease
resistant
20. Linker DNA
• Its size varies from 8bp to 114 bp depending
on the species
• This DNA forms the string part of the beads-
on-a string chromatin fibre, and is nuclease
susceptible; and the beads are due to
nucleosome cores
• Thus, linker DNA joins two neighbouring
nucleosomes
21. H1 Histone
• Each nucleosome contains, on an average, one
molecule of HI histone, although its uniform
distribution throughout the length of chromatin
fibres is not clearly know
• Some studies suggest that the molecules of H1
histone are involved in stabilizing the supercoils
of nucleosome chromatin fibres
• Other studies suggest that HI is associated on the
outside of each nucleosome core, and that one
H1 molecule stabilizes about 166 bp long DNA
molecule
22. Other Chromosomal Proteins:
• Both linker DNA and nucleosome are associated with other
chromosomal proteins
• In native chromatin, the beads are about 110A° in
diameter, 60A° high and ellipsoidal in shape
• Each bead corresponds to a single nucleosome core.
• Under some conditions, nucleosomes pack together
without any linker DNA, which produces the 100A° thick
chromatin fibre called nucleosome fibre which may then
supercoil to give rise to the 300A° chromatin fibre called
solenoid
• The nucleosome model of chromatin fibre structure is
consistent with almost all of the evidence accumulated so
far
23. Special Chromosomes
• Some tissues of certain organisms contain
chromosomes which differ significantly from
normal ones in terms of either morphology or
function; such chromosomes are referred to as
special chromosomes. The following types of
chromosomes may be included under this
category:
• (1) Lampbrush chromosomes,
• (2) Giant chromosomes or salivary gland
chromosomes and
• (3) Accessory or B chromosomes
24. Lampbrush Chromosomes:
• Lampbrush chromosomes are found in oocytes of
many invertebrates and all vertebrates, except
mammals; they have also been reported in human
and rodent oocytes
• But they have been the most extensively studied
in amphibian oocytes
• These chromosomes are most distinctly observed
during the prolonged diplotene stage of oocytes
• During diplotene, the homologous chromosomes
begin to separate from each other, remaining in
contact only at several points along their length
25. Conti…
• Each chromosome of a pair has several chromomeres distributed over its
length; from each of a majority of the chromomeres generally a pair of
lateral loops extends in the opposite directions perpendicular to the main
axis of the chromosome
• In some cases, more than one pair, even upto 9 pairs of loops may emerge
from a single chromomere
• These lateral loops give the chromosomes the appearance of a lampbrush
which is the reason for their name ‘lamp-brush chromosomes’
• These chromosomes are extremely long, in some cases being 800-1000^ in
length
• The size of loops may range from an average of 9.5ja in frog to 200|i in
newt
• The pairs of loops are produced due to uncoiling of the two chromatin
fibres (hence the two sister chromatids) present in a highly coiled state in
the chromosomes; this makes their DNA available for transcription (RNA
synthesis)
26. Conti….
• Thus each loop represents one chromatid of a chromosome and is
composed of one DNA double helix. One end of each loop is thinner (thin
end) than the other end (thick end)
• There is extensive RNA synthesis at the thin ends of loops, while there is
little or no RNA synthesis at the thick end
• The chromatin fibre of the chromomere is progressively uncoiled towards
the thin end of a loop; the DNA in this region supports active RNA
synthesis but later becomes associated with RNA and protein to become
markedly thicker
• The DNA at the thick end of a loop is progressively withdrawn and
reassembled into the chromomere
• The number of pairs of loops gradually increases in meiosis till it reaches
maximum in diplotene
• As meiosis proceeds further, number of loops gradually decreases and the
loops ultimately disappear due to disintegration rather than reabsorption
back into the chromomere
28. Conti…
• Loops represent the sites of gene action
(transcription), and the function of lampbrush
chromosomes is to produce the large numbers
and quantities of proteins and RNA’s stored in
eggs
29. Giant Chromosomes
• Giant chromosomes are found in certain tissues, e.g.,
salivary glands of larvae, gut epithelium, Malphigian
tubules and some Diptera, e.g., Drosophila, Chironomous,
Sciara, Rhyncosciara etc. These chromosomes are very long
(upto 200 times their size during mitotic metaphase in the
case of Drosophila) and very thick, hence they are known
as giant chromosomes
• They were first discovered by Balbiani (1881) in dipteran
salivary glands, giving them the commonly used name
salivary gland chromosomes
• The giant chromosomes are somatically paired.
Consequently, the number of these giant chromosomes in
the salivary gland cells always appear to be half that in the
normal somatic cells
30. Conti….
• The giant chromosomes have a distinct pattern of transverse
banding which consists of alternate chromatic and achromatic
regions
• The bands occasionally form reversible puffs, known as
chromosome puffs or Balabiani rings, which are associated with
active RNA synthesis
• The giant chromosomes represent a bundle of fibrils which arise by
repeated cycles of endo- reduplication (replication of chromatin
without cell-division) of single chromatids
• This is why these chromosomes are also popularly known as
polytene chromosomes and the condition is described as polyteny
• The number of chromonemata (fibrils) per chromosomes may
reach upto 2000 in extreme cases some workers placed this figure
as high as 16,000
31. Conti…
• 2000 in extreme cases some workers placed this figure as high as
16,000
• In D melanogaster, the giant chromosomes radiate as five long and
one short arms from a single more or less amorphous mass known
as chromocentre
• The chromocentre is formed by fusion of the centromeric regions
of all the chromosomes and, in males, of the entire Y chromosomes
• The short arm radiating from the chromocentre represents
chromosome IV, one of the long arms is due to the X-chromosome,
while the remaining four long arms represent the arms of
chromosome II and III
• The total length of D. melanogaster giant chromosomes is about
2000µ.
32.
33. Accessory Chromosomes:
• In many species, one too many extra chro-
mosomes in addition to the normal somatic
complement are found; these extra
chromosomes are called accessory
chromosomes, B-chromosomes or
supernumerary chromosomes.
34. • About 600 plant species and more than 100 animal species
are reported to possess B- chromosomes. B-chromosomes
are generally smaller in size than the chromosomes of the
normal somatic complement but in some species they may
be larger (e.g., in Sciara).
• One of- the most important features of these chromosomes
is that their numbers may vary considerably among
individuals of the same species; in maize as many as 25-30
B-chromosomes may become accumulated in some
individuals without any marked effect on their phenotype
• These chromosomes are generally gained by and lost from
the individuals of a species without any apparent adverse
or beneficial effect
35. Conti…
• However, the presence of several B-chromosomes often leads to
some reduction in vigour and fertility in maize. In most cases, they
are largely heterochromatic, while in some species (e.g. maize) they
are partly heterochromatic, and in some other (e.g., Tradescantia)
they are entirely euchromatic
• They are believed to be generally inactive genetically, but they may
not be completely devoid of genes.
• The origin of B-chromosomes in most species is unknown
• In some animals they may arise due to fragmentation of the
heterochromatic Y chromosome
• In maize, morphological features and pairing behaviour of B-
chromosome clearly shows that they do not have any segment
which is homologous to a segment of any chromosome of the
normal somatic complement
36. Conti…
• B-chromosomes are relatively unstable; in
many species they tend to be eliminated from
somatic tissues due to lagging and non-
disjunction and they frequently change in
morphology through fragmentation
• Further, they may also show irregular
distribution during meiosis, but they are
invariably maintained in the reproductive
tissue
37. Functions of Chromosomes
• The role of chromosomes in heredity was suggested independently
by Sutton and Bover in 1902. This and various other functions of
chromosomes may be summarized as under.
• 1. It is universally accepted that DNA is the genetic material, and
that in eukaryotes almost all the DNA is present in chromosomes.
Thus, the most important function of chromosomes is to provide
the genetic information for various cellular functions essential for
growth, survival, development, reproduction, etc., of organisms.
• 2. Another very important function of chromosomes is to protect
the genetic material (DNA) from being damaged during cell division.
Chromosomes are coated with histones and other proteins which
protect it from both chemical (e.g., enzymes) and physical forces
38. • 3. The properties of chromosomes ensure a
precise distribution of DNA (genetic material) to
the daughter nuclei during cell division
• Centromeres of chromosomes perform an
important function in chromosome movements
during cell division which is due to the
contraction of spindle fibres attached to the
centromeric regions of chromosomes
• 4. Gene action in eukaryotes is believed to be
regulated through histone and non-histone
proteins associated with chromosomes