Dr.S.KARTHIKUMAR
Associate Professor
Department of Biotechnology
Kamaraj College of Engineering and Technology, K.Vellakulam-625701, TN, India
Email: skarthikumar@gmail.com
Mitochondria contain their own circular genome that is 16.5kb in size and located in the mitochondrial matrix. The mitochondrial genome contains 37 genes that encode 13 proteins, 22 tRNAs, and 2 rRNAs. These genes help produce enzymes and proteins that are crucial for oxidative phosphorylation and energy production in mitochondria. The control region of mitochondrial DNA contains signals that regulate mitochondrial DNA and RNA synthesis.
Regulation of eukaryotic gene expressionMd Murad Khan
The document discusses various mechanisms of regulating gene expression in eukaryotes. It explains that regulation can occur at multiple levels, including DNA, transcription, mRNA processing, and protein synthesis. Key points include: (1) Regulation allows adaptation and cellular differentiation; (2) In eukaryotes, transcription and translation are separated, allowing more complex regulation; (3) Regulation mechanisms include controlling chromatin structure, transcription initiation, mRNA splicing/stability, and protein modifications. Environmental factors like heat and hormones can also induce gene expression changes through transcription factors.
Chloroplasts are organelles found in plant cells and algae that conduct photosynthesis. They contain their own DNA known as the chloroplast genome, which is typically 100-200kb in size and encodes genes for photosynthesis. The chloroplast genome is highly conserved and maternally inherited. It has been used for phylogenetic studies and shows potential for genetic engineering due to high transgene expression and maternal inheritance that prevents gene flow to other species.
This document discusses different concepts of genes including:
1. Classical concepts viewed genes as units of heredity, transmission of characters, and mutation.
2. Molecular concepts define genes as the entire nucleic acid sequence required for protein synthesis, including coding and regulatory regions.
3. Genes have a fine structure and can be divided into functional units called cistrons based on complementation testing of mutants.
Nucleosomes are the fundamental repeating subunits of eukaryotic chromatin that package DNA into a compact structure. They are composed of 146 base pairs of DNA wrapped around an octamer of histone proteins, resembling beads on a string. This represents the first order of DNA compaction. Higher orders of compaction involve the nucleosomes winding further to form solenoid fibers, scaffold loops, chromatids, and finally full chromosomes. Nucleosomes allow the long DNA molecules to fit within cell nuclei while also regulating genetic expression.
RNA interference (RNAi): Cellular process by which an mRNA is targeted for degradation by a dsRNA with a strand complementary to a fragment of such mRNA.
Mitochondria contain their own circular genome that is 16.5kb in size and located in the mitochondrial matrix. The mitochondrial genome contains 37 genes that encode 13 proteins, 22 tRNAs, and 2 rRNAs. These genes help produce enzymes and proteins that are crucial for oxidative phosphorylation and energy production in mitochondria. The control region of mitochondrial DNA contains signals that regulate mitochondrial DNA and RNA synthesis.
Regulation of eukaryotic gene expressionMd Murad Khan
The document discusses various mechanisms of regulating gene expression in eukaryotes. It explains that regulation can occur at multiple levels, including DNA, transcription, mRNA processing, and protein synthesis. Key points include: (1) Regulation allows adaptation and cellular differentiation; (2) In eukaryotes, transcription and translation are separated, allowing more complex regulation; (3) Regulation mechanisms include controlling chromatin structure, transcription initiation, mRNA splicing/stability, and protein modifications. Environmental factors like heat and hormones can also induce gene expression changes through transcription factors.
Chloroplasts are organelles found in plant cells and algae that conduct photosynthesis. They contain their own DNA known as the chloroplast genome, which is typically 100-200kb in size and encodes genes for photosynthesis. The chloroplast genome is highly conserved and maternally inherited. It has been used for phylogenetic studies and shows potential for genetic engineering due to high transgene expression and maternal inheritance that prevents gene flow to other species.
This document discusses different concepts of genes including:
1. Classical concepts viewed genes as units of heredity, transmission of characters, and mutation.
2. Molecular concepts define genes as the entire nucleic acid sequence required for protein synthesis, including coding and regulatory regions.
3. Genes have a fine structure and can be divided into functional units called cistrons based on complementation testing of mutants.
Nucleosomes are the fundamental repeating subunits of eukaryotic chromatin that package DNA into a compact structure. They are composed of 146 base pairs of DNA wrapped around an octamer of histone proteins, resembling beads on a string. This represents the first order of DNA compaction. Higher orders of compaction involve the nucleosomes winding further to form solenoid fibers, scaffold loops, chromatids, and finally full chromosomes. Nucleosomes allow the long DNA molecules to fit within cell nuclei while also regulating genetic expression.
RNA interference (RNAi): Cellular process by which an mRNA is targeted for degradation by a dsRNA with a strand complementary to a fragment of such mRNA.
This document summarizes the process of nuclear export of messenger RNA (mRNA). It begins with an introduction describing how mRNA must be exported from the nucleus to the cytoplasm to be translated into protein. It then discusses the importance of nuclear export and describes the nuclear pore complex that facilitates transport. The document outlines the roles of Ran GTPase and transport receptors in nuclear export. It provides details on the adaptor-receptor system and multistep process of mRNA export, including recruitment of export factors, translocation through the nuclear pore, and release into the cytoplasm. The summary concludes with sections on regulation and quality control of mRNA export.
Chloroplasts are double-membrane organelles found in plant cells that contain chlorophyll and are the site of photosynthesis. Chloroplast DNA is circular and ranges in size from 120,000 to 170,000 base pairs. It contains approximately 120 genes, including genes that encode proteins involved in photosynthesis and the transcription and translation machinery. Chloroplast DNA replication is semi-conservative and there are typically multiple copies of the chloroplast genome within each chloroplast.
This document discusses transposable elements (TEs), which are segments of DNA that can move within genomes. It covers their discovery by Barbara McClintock in corn in the 1940s. TEs are classified into different types based on their structure and mechanism of movement. The document also examines the mechanisms of transposition, mutagenic effects, regulation, and presence of TEs across bacteria, fungi, and eukaryotes like humans. TEs make up a large fraction of genomes and contribute to genetic variation and disease.
RNA splicing is a process where introns are removed from precursor messenger RNA (pre-mRNA) and exons are joined together to produce mature mRNA. It occurs in the nucleus and is essential for eukaryotes to produce proteins. The spliceosome, a large complex of RNA and proteins, facilitates two transesterification reactions that remove introns and ligate exons. RNA splicing generates protein diversity through alternative splicing and is important for cellular functions and disease processes.
This document discusses the C-Value Paradox, which is the observation that there is no correlation between the complexity of an organism and the amount of DNA (C-value) in its genome. The document provides examples showing that C-values, or the amount of DNA per haploid cell, can vary widely both within and across species, from 105 base pairs in mycoplasma to over 109 base pairs in mammals. While complexity tends to increase with higher C-values, exceptions exist, demonstrating there is no direct linear relationship between genome size and organism complexity. The term "C-value" refers to the haploid DNA content of a species.
Protein targeting or protein sorting is the mechanism by which a cell transports to the appropriate positions in the cell or outside of it. Both in prokaryotes and eukaryotes, newly synthesized proteins must be delivered to a specific sub-cellular location or exported from the cell for correct activity. This phenomenon is called protein targeting. Protein targeting is necessary for proteins that are destined to work outside the cytoplasm.This delivery process is carried out based on information contained in the protein itself. Correct sorting is crucial for the cell; errors can lead to diseases. In 1970, Günter Blobel conducted experiments on the translocation of proteins across membranes. He was awarded the 1999 Nobel Prize for his findings. He discovered that many proteins have a signal sequence, that is, a short amino acid sequence at one end that functions like a postal code for the target organelle.
DNA methylation is a biological process where methyl groups are added to DNA, changing gene expression without altering the DNA sequence. It is essential for normal development in mammals and is associated with processes like genomic imprinting and carcinogenesis. DNA methyltransferases are enzymes that catalyze the addition of methyl groups to DNA from S-adenosyl methionine. DNA methylation plays important roles in gene silencing, X-chromosome inactivation, and suppressing viral genomes and repetitive elements incorporated into the host genome. Abnormal DNA methylation is also associated with cancer by transcriptionally silencing tumor suppressor genes.
Map-based cloning is a technique used to identify the genetic cause of a mutant phenotype by isolating overlapping DNA segments that progress along the chromosome toward a candidate gene. The process involves initially identifying a marker close to the gene of interest and then saturating the region with additional markers. Large populations are screened to find markers that rarely recombine with the gene. Genomic libraries are screened to find clones containing the markers, and chromosomal walking is used to obtain flanking markers on a single clone. DNA fragments between the markers are tested to rescue the wild-type phenotype and identify the candidate gene.
Mitochondria contain their own DNA and play an essential role in cellular respiration by generating ATP. While small, the mitochondrial genome encodes components of the electron transport chain. Manipulation of the mitochondrial genome holds promise for crop improvement due to maternal inheritance and absence of position effects. However, transforming the mitochondrial genome remains challenging due to difficulties incorporating foreign DNA and a lack of selectable markers. Successful manipulation could generate cytoplasmic male sterility for hybrid seed production.
This document discusses site-specific recombination, including the structures and mechanisms involved. It describes two classes of recombinases - tyrosine recombinases and serine recombinases. Tyrosine recombinases involve cleavage of DNA through formation of a protein-DNA bond using a tyrosine residue. Serine recombinases utilize a phosphoserine bond between DNA and a conserved serine residue. The document provides examples of applications for site-specific recombination such as tracking cell lineage, altering gene expression, and targeted gene knockout.
There are three main methods for isolating genes:
1. Using an automated gene machine to synthesize genes from predetermined nucleotide sequences.
2. Gene cloning, which involves inserting a DNA fragment into a vector that is then transferred into a host cell to produce multiple copies.
3. Polymerase chain reaction (PCR), which amplifies a specific DNA sequence using primers that flank the target sequence.
Chromosomes are rod-shaped structures found in the nucleus that carry genetic information. They become visible during cell division. In situ hybridization (ISH) allows the localization of nucleic acid sequences on chromosomes using probes. Fluorescence in situ hybridization (FISH) is a type of ISH that uses fluorescent probes to visualize specific sequences. FISH has applications in gene mapping, detecting genetic abnormalities, and identifying chromosomes.
RNA polymerase is an essential enzyme that copies DNA to produce different types of RNA in prokaryotes and eukaryotes. In prokaryotes, a single type of RNA polymerase synthesizes mRNA, tRNA, and rRNA. Transcription in prokaryotes involves initiation at promoter sequences, elongation as the RNA polymerase moves along DNA, and termination at specific sequences. Initiation requires the RNA polymerase binding to the promoter, unwinding the DNA, and beginning RNA synthesis. Elongation continues RNA synthesis as the DNA unwinds. Termination occurs at specific sequences like palindromes that allow RNA secondary structure formation and polymerase release.
RNA Polymerase
Introduction
Purification
History
PRODUCTS OF RNAP
Messenger RNA
Non-coding RNA or "RNA genes
Transfer RNA
Ribosomal RNA
Micro RNA
Catalytic RNA (Ribozyme)
prokaryotic and eukaryotic
Transcription by RNA Polymerase
TYPES OF RNA POLYMERASE
Type I
Type II
Type III
Prokaryotic Transcription Unit
EXPRESSION OF A PROKARYOTIC GENE
Prokaryotic Polycistronic Message Codes for Several Different Proteins
Eukaryotic Transcription Unit
ENHANCERS AND SILENCERS
RESULT OF THE TRANSCRIPTION CYCLE
RNAP III TRANSCRIBES HUMAN MICRORNAS
RNAP I–specific subunits promotepolymerase clustering to enhance the rRNA genetranscription cycle
RNAP II–TFIIB STRUCTURE ANDMECHANISM OF TRANSCRIPTION INITIATION
FIVE CHECKPOINTS MAINTAINING THE FIDELITY OFTRANSCRIPTION BY RNAP IN STRUCTURAL ANDENERGETIC DETAILS
This document summarizes the process of translation in prokaryotes. It begins with an introduction to translation occurring in the cytoplasm where ribosomes synthesize proteins using messenger RNA (mRNA). The three main stages of translation are then described in detail: initiation, elongation, and termination. Initiation involves assembly of the ribosome and initiation factors on the mRNA start codon. Elongation is the process of adding amino acids to the growing polypeptide chain through binding of transfer RNA (tRNA) and the actions of elongation factors. Termination occurs when a stop codon is reached and release factors trigger hydrolysis and release of the completed protein. Key components of translation like ribosomes, mRNA, tRNA, and their functions are
N-terminal tails of histones are the most accessible regions for modifications. These post-translational modification (PTM) of histones is a crucial step in epigenetic regulation of a gene.
This document discusses chloroplast DNA (cpDNA). Chloroplasts contain their own circular genome of double-stranded DNA ranging from 140-200kb. The cpDNA contains genes that code for proteins involved in photosynthesis as well as rRNA and tRNA. It has a quadripartite structure containing single copy and inverted repeat regions. Tobacco and liverwort were two of the first chloroplast genomes to be sequenced. Molecular studies of cpDNA regions have been useful for plant systematics. Replication of cpDNA is independent of nuclear DNA and involves enzymes like DNA polymerase and helicase.
This document provides information about mitochondria and ribosomes. It discusses the structure, composition, and functions of mitochondria and ribosomes. Some key points:
- Mitochondria are organelles found in the cytoplasm that generate energy through oxidative phosphorylation. They have an outer and inner membrane and contain enzymes for cellular respiration.
- Ribosomes are subcellular particles found in both prokaryotes and eukaryotes that facilitate protein synthesis. They consist of RNA and protein subunits.
- Both mitochondria and ribosomes play essential roles in cellular metabolism and protein production. Mitochondria generate energy through respiration while ribosomes assemble amino acids into proteins.
1. Mitochondria are organelles found in animal cells that produce ATP through cellular respiration. They have an outer and inner membrane that create compartments and folds called cristae that house the electron transport chain.
2. Mitochondria contain their own circular DNA and ribosomes. They are the powerhouses of the cell and only inherited maternally.
3. Mitochondria have many functions including ATP production, generating reactive oxygen species, programmed cell death, cellular proliferation, and heat production. They also play roles in various metabolic processes.
This document summarizes the process of nuclear export of messenger RNA (mRNA). It begins with an introduction describing how mRNA must be exported from the nucleus to the cytoplasm to be translated into protein. It then discusses the importance of nuclear export and describes the nuclear pore complex that facilitates transport. The document outlines the roles of Ran GTPase and transport receptors in nuclear export. It provides details on the adaptor-receptor system and multistep process of mRNA export, including recruitment of export factors, translocation through the nuclear pore, and release into the cytoplasm. The summary concludes with sections on regulation and quality control of mRNA export.
Chloroplasts are double-membrane organelles found in plant cells that contain chlorophyll and are the site of photosynthesis. Chloroplast DNA is circular and ranges in size from 120,000 to 170,000 base pairs. It contains approximately 120 genes, including genes that encode proteins involved in photosynthesis and the transcription and translation machinery. Chloroplast DNA replication is semi-conservative and there are typically multiple copies of the chloroplast genome within each chloroplast.
This document discusses transposable elements (TEs), which are segments of DNA that can move within genomes. It covers their discovery by Barbara McClintock in corn in the 1940s. TEs are classified into different types based on their structure and mechanism of movement. The document also examines the mechanisms of transposition, mutagenic effects, regulation, and presence of TEs across bacteria, fungi, and eukaryotes like humans. TEs make up a large fraction of genomes and contribute to genetic variation and disease.
RNA splicing is a process where introns are removed from precursor messenger RNA (pre-mRNA) and exons are joined together to produce mature mRNA. It occurs in the nucleus and is essential for eukaryotes to produce proteins. The spliceosome, a large complex of RNA and proteins, facilitates two transesterification reactions that remove introns and ligate exons. RNA splicing generates protein diversity through alternative splicing and is important for cellular functions and disease processes.
This document discusses the C-Value Paradox, which is the observation that there is no correlation between the complexity of an organism and the amount of DNA (C-value) in its genome. The document provides examples showing that C-values, or the amount of DNA per haploid cell, can vary widely both within and across species, from 105 base pairs in mycoplasma to over 109 base pairs in mammals. While complexity tends to increase with higher C-values, exceptions exist, demonstrating there is no direct linear relationship between genome size and organism complexity. The term "C-value" refers to the haploid DNA content of a species.
Protein targeting or protein sorting is the mechanism by which a cell transports to the appropriate positions in the cell or outside of it. Both in prokaryotes and eukaryotes, newly synthesized proteins must be delivered to a specific sub-cellular location or exported from the cell for correct activity. This phenomenon is called protein targeting. Protein targeting is necessary for proteins that are destined to work outside the cytoplasm.This delivery process is carried out based on information contained in the protein itself. Correct sorting is crucial for the cell; errors can lead to diseases. In 1970, Günter Blobel conducted experiments on the translocation of proteins across membranes. He was awarded the 1999 Nobel Prize for his findings. He discovered that many proteins have a signal sequence, that is, a short amino acid sequence at one end that functions like a postal code for the target organelle.
DNA methylation is a biological process where methyl groups are added to DNA, changing gene expression without altering the DNA sequence. It is essential for normal development in mammals and is associated with processes like genomic imprinting and carcinogenesis. DNA methyltransferases are enzymes that catalyze the addition of methyl groups to DNA from S-adenosyl methionine. DNA methylation plays important roles in gene silencing, X-chromosome inactivation, and suppressing viral genomes and repetitive elements incorporated into the host genome. Abnormal DNA methylation is also associated with cancer by transcriptionally silencing tumor suppressor genes.
Map-based cloning is a technique used to identify the genetic cause of a mutant phenotype by isolating overlapping DNA segments that progress along the chromosome toward a candidate gene. The process involves initially identifying a marker close to the gene of interest and then saturating the region with additional markers. Large populations are screened to find markers that rarely recombine with the gene. Genomic libraries are screened to find clones containing the markers, and chromosomal walking is used to obtain flanking markers on a single clone. DNA fragments between the markers are tested to rescue the wild-type phenotype and identify the candidate gene.
Mitochondria contain their own DNA and play an essential role in cellular respiration by generating ATP. While small, the mitochondrial genome encodes components of the electron transport chain. Manipulation of the mitochondrial genome holds promise for crop improvement due to maternal inheritance and absence of position effects. However, transforming the mitochondrial genome remains challenging due to difficulties incorporating foreign DNA and a lack of selectable markers. Successful manipulation could generate cytoplasmic male sterility for hybrid seed production.
This document discusses site-specific recombination, including the structures and mechanisms involved. It describes two classes of recombinases - tyrosine recombinases and serine recombinases. Tyrosine recombinases involve cleavage of DNA through formation of a protein-DNA bond using a tyrosine residue. Serine recombinases utilize a phosphoserine bond between DNA and a conserved serine residue. The document provides examples of applications for site-specific recombination such as tracking cell lineage, altering gene expression, and targeted gene knockout.
There are three main methods for isolating genes:
1. Using an automated gene machine to synthesize genes from predetermined nucleotide sequences.
2. Gene cloning, which involves inserting a DNA fragment into a vector that is then transferred into a host cell to produce multiple copies.
3. Polymerase chain reaction (PCR), which amplifies a specific DNA sequence using primers that flank the target sequence.
Chromosomes are rod-shaped structures found in the nucleus that carry genetic information. They become visible during cell division. In situ hybridization (ISH) allows the localization of nucleic acid sequences on chromosomes using probes. Fluorescence in situ hybridization (FISH) is a type of ISH that uses fluorescent probes to visualize specific sequences. FISH has applications in gene mapping, detecting genetic abnormalities, and identifying chromosomes.
RNA polymerase is an essential enzyme that copies DNA to produce different types of RNA in prokaryotes and eukaryotes. In prokaryotes, a single type of RNA polymerase synthesizes mRNA, tRNA, and rRNA. Transcription in prokaryotes involves initiation at promoter sequences, elongation as the RNA polymerase moves along DNA, and termination at specific sequences. Initiation requires the RNA polymerase binding to the promoter, unwinding the DNA, and beginning RNA synthesis. Elongation continues RNA synthesis as the DNA unwinds. Termination occurs at specific sequences like palindromes that allow RNA secondary structure formation and polymerase release.
RNA Polymerase
Introduction
Purification
History
PRODUCTS OF RNAP
Messenger RNA
Non-coding RNA or "RNA genes
Transfer RNA
Ribosomal RNA
Micro RNA
Catalytic RNA (Ribozyme)
prokaryotic and eukaryotic
Transcription by RNA Polymerase
TYPES OF RNA POLYMERASE
Type I
Type II
Type III
Prokaryotic Transcription Unit
EXPRESSION OF A PROKARYOTIC GENE
Prokaryotic Polycistronic Message Codes for Several Different Proteins
Eukaryotic Transcription Unit
ENHANCERS AND SILENCERS
RESULT OF THE TRANSCRIPTION CYCLE
RNAP III TRANSCRIBES HUMAN MICRORNAS
RNAP I–specific subunits promotepolymerase clustering to enhance the rRNA genetranscription cycle
RNAP II–TFIIB STRUCTURE ANDMECHANISM OF TRANSCRIPTION INITIATION
FIVE CHECKPOINTS MAINTAINING THE FIDELITY OFTRANSCRIPTION BY RNAP IN STRUCTURAL ANDENERGETIC DETAILS
This document summarizes the process of translation in prokaryotes. It begins with an introduction to translation occurring in the cytoplasm where ribosomes synthesize proteins using messenger RNA (mRNA). The three main stages of translation are then described in detail: initiation, elongation, and termination. Initiation involves assembly of the ribosome and initiation factors on the mRNA start codon. Elongation is the process of adding amino acids to the growing polypeptide chain through binding of transfer RNA (tRNA) and the actions of elongation factors. Termination occurs when a stop codon is reached and release factors trigger hydrolysis and release of the completed protein. Key components of translation like ribosomes, mRNA, tRNA, and their functions are
N-terminal tails of histones are the most accessible regions for modifications. These post-translational modification (PTM) of histones is a crucial step in epigenetic regulation of a gene.
This document discusses chloroplast DNA (cpDNA). Chloroplasts contain their own circular genome of double-stranded DNA ranging from 140-200kb. The cpDNA contains genes that code for proteins involved in photosynthesis as well as rRNA and tRNA. It has a quadripartite structure containing single copy and inverted repeat regions. Tobacco and liverwort were two of the first chloroplast genomes to be sequenced. Molecular studies of cpDNA regions have been useful for plant systematics. Replication of cpDNA is independent of nuclear DNA and involves enzymes like DNA polymerase and helicase.
This document provides information about mitochondria and ribosomes. It discusses the structure, composition, and functions of mitochondria and ribosomes. Some key points:
- Mitochondria are organelles found in the cytoplasm that generate energy through oxidative phosphorylation. They have an outer and inner membrane and contain enzymes for cellular respiration.
- Ribosomes are subcellular particles found in both prokaryotes and eukaryotes that facilitate protein synthesis. They consist of RNA and protein subunits.
- Both mitochondria and ribosomes play essential roles in cellular metabolism and protein production. Mitochondria generate energy through respiration while ribosomes assemble amino acids into proteins.
1. Mitochondria are organelles found in animal cells that produce ATP through cellular respiration. They have an outer and inner membrane that create compartments and folds called cristae that house the electron transport chain.
2. Mitochondria contain their own circular DNA and ribosomes. They are the powerhouses of the cell and only inherited maternally.
3. Mitochondria have many functions including ATP production, generating reactive oxygen species, programmed cell death, cellular proliferation, and heat production. They also play roles in various metabolic processes.
About how cellular respiration occurs in Mitochondria, it discusses first the parts and functions of mitochondrion then the types of respiration and the 3 processes occurs in aerobic respiration.
The document provides information on mitochondria, including:
1) Mitochondria produce energy (ATP) for cellular processes through oxidative phosphorylation and contain double membranes.
2) They likely originated from endosymbiotic bacteria and contain their own DNA.
3) Mitochondria convert pyruvate and fatty acids into ATP through the citric acid cycle and electron transport chain located in the inner membrane. This establishes a proton gradient used to synthesize ATP.
The document discusses three proposed mechanisms for the formation of mitochondria: self-duplication of existing mitochondria, de novo origin from cytoplasmic vesicles, and transformation from non-mitochondrial systems like the plasma membrane or ER. It states that the self-duplication hypothesis through fission of existing mitochondria is now most widely accepted. The endosymbiont hypothesis that mitochondria evolved from prokaryotes engulfed by early eukaryotic cells over a billion years ago is also described. Mitochondria's key functions like ATP production through oxidative phosphorylation are summarized.
Mitochondria are cytoplasmic organelles found in eukaryotic cells that generate most of the cell's supply of ATP through oxidative phosphorylation. They have an outer membrane and inner membrane, with the inner membrane forming infoldings called cristae. Mitochondria contain their own DNA and ribosomes and can replicate independently of the cell. They play a key role in cellular respiration by producing ATP from the oxidation of pyruvate and the citric acid cycle.
This document provides an overview of key concepts for biology EOC review. It begins by outlining the scientific method and characteristics of life. It then discusses cells and cell processes like cellular transport, photosynthesis, and cellular respiration. Additional sections cover DNA, RNA, protein synthesis, mitosis, meiosis, genetics, and ecology. The document provides definitions and explanations of important biology concepts and is intended to help students prepare for the end of course biology exam.
This document provides an overview of key concepts covered on the Biology EOC exam, including:
1. Science methods like experimentation, identifying independent and dependent variables, and organizing data in tables and graphs.
2. Characteristics of life such as cellular organization, reproduction, metabolism, homeostasis, heredity, response to stimuli, growth and development, and evolution.
3. Biology topics such as chemistry of macromolecules, cellular transport, photosynthesis, cellular respiration, DNA structure and protein synthesis, ecology, cell structure, and mitosis and meiosis.
The document discusses several topics related to cell structures and functions:
1. The centrosome, which is located near the nucleus and consists of a pair of centrioles surrounded by granular material. It duplicates and separates to form the poles of the mitotic spindle during cell division.
2. Mitochondria, which transform chemical energy into ATP and regulate calcium levels. They have an outer and inner membrane with cristae that increase surface area for oxidative phosphorylation.
3. Cytoplasmic inclusions like glycogen, lipids, crystals, and pigments that are not bound by membranes and serve storage or protective functions in cells.
Mitochondria are cellular organelles that produce energy through oxidative phosphorylation. They contain their own DNA and have a double membrane structure. The inner membrane of the mitochondrion contains electron transport chain complexes that generate a proton gradient by pumping hydrogen ions across the membrane. This gradient is used by ATP synthase to produce ATP from ADP and inorganic phosphate. Mitochondria play a key role in cellular respiration and energy production and mutations in mitochondrial DNA can cause various human diseases due to their exclusively maternal inheritance pattern.
Mitochondria are cytoplasmic organelles found in eukaryotic cells that generate most of the cell's supply of adenosine triphosphate (ATP), used as a source of chemical energy. They contain a double membrane, with the inner membrane folded into cristae that contain enzymes involved in oxidative phosphorylation. Mitochondria also contain their own circular DNA and ribosomes. They are thought to have originated from symbiotic bacteria and play a key role in cellular respiration by harnessing energy from the oxidation of pyruvate and fatty acids to produce ATP.
Mitochondria are cytoplasmic organelles found in eukaryotic cells that generate most of the cell's supply of adenosine triphosphate (ATP), used as a source of chemical energy. They contain a double membrane, with the inner membrane folded into cristae that contain enzymes involved in oxidative phosphorylation. Mitochondria also contain their own circular DNA and ribosomes. They are believed to have originated from symbiotic bacteria and play a key role in cellular respiration by harnessing energy from the oxidation of carbohydrates and fats to produce ATP.
Mitochondria are cytoplasmic organelles that generate most of the cell's supply of ATP through oxidative phosphorylation. They contain their own DNA and ribosomes. Mitochondria have a double membrane structure with an inner membrane that forms folds called cristae. They are thought to have evolved from bacteria that developed an endosymbiotic relationship with early eukaryotic cells. The human mitochondrial genome is 16kb and encodes 13 proteins as well as tRNAs and rRNAs that are essential for oxidative phosphorylation.
Mitochondria are cytoplasmic organelles that generate most of the cell's supply of ATP through oxidative phosphorylation. They contain their own DNA and have a double membrane structure with an inner membrane that forms folds called cristae. Mitochondria convert the energy from carbohydrates and fats into ATP through a series of metabolic pathways, including glycolysis in the cytosol, the citric acid cycle in the mitochondrial matrix, and the electron transport chain located in the inner mitochondrial membrane. This process results in ATP production through oxidative phosphorylation and the creation of a proton gradient across the inner membrane.
This document discusses the endosymbiotic theory of the origin of mitochondria and chloroplasts. It provides an overview of mitochondria and chloroplasts, including their DNA, proteins, membranes, and replication processes. The document also examines Archaezoa, which are eukaryotes lacking mitochondria, and explores various hypotheses for their origin. Overall, the document analyzes the endosymbiotic theory and evidence in support of mitochondria and chloroplasts originating from ancient bacterial endosymbionts.
Mitochondria are double-membrane organelles found in the cytoplasm of eukaryotic cells. They produce ATP through oxidative phosphorylation to power the cell's activities. Mitochondria contain their own circular DNA and ribosomes. They likely originated through the endosymbiosis of ancient bacteria by early eukaryotic cells. The inner membrane of mitochondria is folded into cristae to increase surface area for ATP production. Mitochondria vary in size, shape, and number depending on the cell type but perform essential functions like aerobic respiration.
The document summarizes cellular classification and subcellular organelles. It describes the two main types of cells - prokaryotic and eukaryotic. It then discusses the structures and functions of various eukaryotic organelles such as the nucleus, mitochondria, chloroplasts, lysosomes, endoplasmic reticulum, and Golgi apparatus. Finally, it summarizes the four main classes of macromolecules - carbohydrates, lipids, proteins, and nucleic acids - and provides examples of structures and functions within each class.
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.
Cell signaling, regulating mechanism and structureGunJee Gj
The document summarizes key components of cell signaling and regulation. It describes how the cytoplasm transports materials and maintains cell shape and consistency. It also explains how the nucleus houses genetic material and regulates metabolic processes. Additionally, it outlines the roles of ribosomes, endoplasmic reticulum, Golgi apparatus, lysosomes, peroxisomes, and mitochondria. Finally, it provides an overview of different forms of intercellular signaling, including autocrine, paracrine, endocrine, direct, and synaptic signaling, and how cells receive and transmit signals through membrane receptors and intracellular messengers.
cell biology class 17th N ovember mitochondria 2015.pptsubhashree533922
Mitochondria have their own DNA that is circular and resembles bacterial DNA. In humans, mitochondrial DNA is 16,569 base pairs and encodes 13 proteins, 22 tRNAs and 2 rRNAs. Mitochondrial DNA is inherited from both parents in yeast and animals. Plants have larger, more variable mitochondrial genomes that can contain chloroplast DNA. Mitochondria replicate through fission and distribute randomly between daughter cells during cell division.
A bacteriophage is a virus that infects bacteria. Lambda phage is a temperate bacteriophage that has two life cycle choices: lytic and lysogenic. During lysogeny, the lambda repressor binds to the operator region (OR) on the phage DNA and represses transcription of lytic genes, allowing the phage genome to remain dormant as a prophage integrated into the bacterial chromosome.
The trp operon controls the biosynthesis of tryptophan in E. coli. It contains 5 genes that encode enzymes for tryptophan production. The operon uses attenuation to regulate expression based on tryptophan levels. When tryptophan is low, transcription proceeds through the leader sequence. When tryptophan is high, translation is rapid and a stem loop structure forms, terminating transcription. The trp operon is a repressible system, where the effector molecule allows the repressor to bind the operator and shut down expression.
The document summarizes the lac operon in E. coli, which controls the breakdown of lactose. The lac operon contains 3 genes - lacZ, lacY, and lacA - that code for enzymes involved in lactose catabolism. In the absence of lactose, a repressor protein binds to the operator region and prevents transcription. In the presence of lactose, it binds to the repressor and induces transcription of the structural genes. The lac operon demonstrates both negative control by the repressor and positive control through induction by lactose binding. Glucose also regulates the operon through catabolite repression involving cAMP levels.
Post-translational modifications (PTMs) are chemical changes that occur to proteins after translation. PTMs regulate protein activity, localization, and interactions. The main types of PTMs are phosphorylation, glycosylation, ubiquitination, and methylation. Phosphorylation involves the addition of phosphate groups and is important for cell signaling. Glycosylation adds carbohydrate groups and affects protein structure. Ubiquitination tags proteins for destruction, and methylation adds methyl groups, regulating processes like gene expression. PTMs are identified through techniques like mass spectrometry and chromatographic analysis.
Aminoglycosides like streptomycin bind to the 30S ribosomal subunit and interfere with initiation complex formation, inducing misreading of mRNA and breaking polysomes into monosomes. Chloramphenicol inhibits protein synthesis by binding reversibly to the 50S ribosomal subunit and preventing the binding of aminoacyl tRNA to the acceptor site. Tetracyclines also bind to the 30S ribosomal subunit but prevent the binding of aminoacyl tRNA to the mRNA ribosome complex. Macrolides inhibit protein synthesis by reversibly binding to the 50S ribosomal subunit and suppressing translocation of mRNA.
Protein synthesis involves three main steps - initiation, elongation, and termination. In initiation, the small and large ribosomal subunits assemble along with mRNA and tRNA to form the initiation complex. In elongation, amino acids are added one by one to the growing polypeptide chain. Termination occurs when a stop codon is reached, causing the release of the completed protein. While the overall process is similar between prokaryotes and eukaryotes, there are some key differences like the number of initiation factors and whether mRNA is polycistronic or monocistronic.
Ribosomes are organelles found in all cells that synthesize proteins. They consist of RNA and proteins and exist as two subunits - a smaller 30S subunit in prokaryotes and 40S in eukaryotes, and a larger 50S subunit in prokaryotes and 60S in eukaryotes. Ribosomes translate mRNA into proteins through initiation, elongation, and termination steps. Errors in ribosome functioning can lead to improper protein folding and diseases.
This document discusses genetic code, tRNA, and translation. It provides definitions of key terms like codon, anticodon, wobble hypothesis. It describes the structure and function of tRNA, including how it is charged with specific amino acids by aminoacyl tRNA synthetases. The document also discusses characteristics of the genetic code, including that it is degenerate, uses triplet codons, and has start and stop signals. It provides information on ribosomes, including their composition in prokaryotes and eukaryotes. In summary, the document provides an overview of the mechanisms and key components involved in translating genetic code into proteins.
Mutation is a change in genetic material that can be caused by errors during DNA replication or DNA repair. There are several types of mutations including point mutations, insertions, deletions, and chromosomal mutations. Point mutations include transitions, transversions, missense mutations, and nonsense mutations. Insertions and deletions can disrupt the genetic code. Spontaneous mutations arise naturally while induced mutations are caused by mutagens like radiation, chemicals, or viruses. Mutations can be germline or somatic and can have different effects on protein function and the phenotype. The document provides examples of specific mutations and their effects.
Telomeres are repetitive DNA sequences at the ends of chromosomes that protect them from degradation. Telomeres naturally shorten each time a cell divides until they reach a critical shortness that causes cell senescence. Telomerase is an enzyme that adds telomere repeats to chromosome ends and counteracts shortening. It is active in 90% of cancer cells, allowing unlimited cell division by maintaining telomere length, but is not generally active in most adult somatic cells.
This document discusses DNA replication and the central dogma. It covers the basic requirements for DNA replication including substrates, templates, enzymes, and primers. The stages of replication - initiation, elongation, and termination - are described. Key aspects of the replication process are explained, such as semi-conservative mechanism, unwinding of DNA, formation of replication forks, and bidirectional replication. Differences between prokaryotic and eukaryotic DNA replication are highlighted. Finally, various inhibitors of DNA replication are listed.
RNA differs from DNA in several key ways. RNA is typically single-stranded, contains ribose sugar instead of deoxyribose, and contains uracil instead of thymine. There are multiple types of RNA that serve different cellular functions, including messenger RNA (mRNA), transfer RNA (tRNA), and ribosomal RNA (rRNA). mRNA carries coding information from DNA to the ribosome for protein synthesis. tRNA transfers amino acids to the ribosome during protein assembly according to the mRNA codon sequence. rRNA is a core component of ribosomes and facilitates protein translation.
Transcriptional regulatory elements such as promoters, enhancers, silencers, and insulators help control gene expression. Promoters initiate transcription and contain core and proximal elements. Enhancers can activate transcription from farther distances by binding activator proteins. Silencers negatively regulate genes by binding repressor proteins. Insulators block interactions between genes to prevent neighboring transcriptional effects. These cis-acting elements help precisely regulate protein levels through transcriptional mechanisms.
Ribozymes are RNA molecules that act as enzymes and catalyze biochemical reactions. They were first discovered in 1982 by Thomas Czech and Sidney Altman, who later won the Nobel Prize in Chemistry for their discovery. Ribozymes increase the rate and specificity of reactions like phosphodiester bond cleavage and peptide bond synthesis. Common types of ribozymes include self-splicing introns, RNase P, hammerhead ribozymes, and hairpin ribozymes. Artificial ribozymes can also be synthesized in the laboratory by mutating natural ribozymes.
Rifampicin binds to the beta subunit of prokaryotic RNA polymerase, inhibiting prokaryotic transcription initiation. It selectively binds bacterial RNA polymerase without affecting eukaryotic polymerases. This allows rifampicin to be an effective treatment for bacterial infections like tuberculosis and leprosy. Alpha amanitin from death cap mushrooms potently inhibits RNA polymerase II during both transcription initiation and elongation, potentially causing death in 10 days from just one mushroom due to failure of gene expression.
Eukaryotic pre-mRNA undergoes processing in the nucleus before being exported to the cytoplasm for protein synthesis. This involves adding a 5' cap and poly-A tail to increase stability and facilitate export. Introns are also spliced out by the spliceosome, a complex of small nuclear RNAs and proteins that cuts out introns and joins exons to form mature mRNA. Capping occurs at the 5' end shortly after transcription, while polyadenylation adds around 200 adenine nucleotides to the 3' end. Splicing removes intervening intron sequences by cutting and religating exons. These processing steps produce translation-competent mRNA from initial pre-mRNA transcripts.
Transcription is the first step in gene expression for eukaryotic organisms where DNA is copied into RNA. This process involves RNA polymerase binding to promoter regions on DNA and synthesizing a complementary RNA strand. Transcription results in RNA transcripts that can then undergo further processing and modification before being translated into proteins.
The document summarizes transcription in prokaryotes. It discusses the key components including the template strand, coding strand, and RNA polymerase. RNA polymerase is made up of multiple subunits and recognizes promoter sequences to initiate transcription. The process of transcription involves three phases - initiation when RNA polymerase binds to the promoter, elongation as the RNA strand continuously grows, and termination when RNA polymerase stops synthesis.
DNA is a double-helix molecule that carries genetic instructions. It is composed of two strands called polynucleotides made up of nucleotides, each containing a nucleobase (A, T, C, or G), sugar, and phosphate. The strands are stabilized by hydrogen bonds between nucleotides and base stacking. DNA can be denatured by heat, pH extremes, or chemicals, breaking the hydrogen bonds and separating the strands. Denaturation temperature depends on factors like composition, length, and environment. Renaturation occurs when strands reconnect under appropriate conditions.
DNA's double helical structure is stabilized by several weak forces that collectively provide strong stabilization. Hydrogen bonding between complementary base pairs provides some stability, while base stacking interactions between the hydrophobic bases, including hydrophobic and van der Waals forces, provide additional stability by burying the bases in the interior. Ionic interactions between the negatively charged phosphate backbone and positive ions like magnesium also contribute to stability. Though each individual interaction is weak, the collective effects of all of these forces interacting along the entire DNA molecule strongly stabilize its double helical structure.
More from Department of Biotechnology, Kamaraj college of engineering and technology (20)
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.
JAMES WEBB STUDY THE MASSIVE BLACK HOLE SEEDSSérgio Sacani
The pathway(s) to seeding the massive black holes (MBHs) that exist at the heart of galaxies in the present and distant Universe remains an unsolved problem. Here we categorise, describe and quantitatively discuss the formation pathways of both light and heavy seeds. We emphasise that the most recent computational models suggest that rather than a bimodal-like mass spectrum between light and heavy seeds with light at one end and heavy at the other that instead a continuum exists. Light seeds being more ubiquitous and the heavier seeds becoming less and less abundant due the rarer environmental conditions required for their formation. We therefore examine the different mechanisms that give rise to different seed mass spectrums. We show how and why the mechanisms that produce the heaviest seeds are also among the rarest events in the Universe and are hence extremely unlikely to be the seeds for the vast majority of the MBH population. We quantify, within the limits of the current large uncertainties in the seeding processes, the expected number densities of the seed mass spectrum. We argue that light seeds must be at least 103 to 105 times more numerous than heavy seeds to explain the MBH population as a whole. Based on our current understanding of the seed population this makes heavy seeds (Mseed > 103 M⊙) a significantly more likely pathway given that heavy seeds have an abundance pattern than is close to and likely in excess of 10−4 compared to light seeds. Finally, we examine the current state-of-the-art in numerical calculations and recent observations and plot a path forward for near-future advances in both domains.
Evidence of Jet Activity from the Secondary Black Hole in the OJ 287 Binary S...Sérgio Sacani
Wereport the study of a huge optical intraday flare on 2021 November 12 at 2 a.m. UT in the blazar OJ287. In the binary black hole model, it is associated with an impact of the secondary black hole on the accretion disk of the primary. Our multifrequency observing campaign was set up to search for such a signature of the impact based on a prediction made 8 yr earlier. The first I-band results of the flare have already been reported by Kishore et al. (2024). Here we combine these data with our monitoring in the R-band. There is a big change in the R–I spectral index by 1.0 ±0.1 between the normal background and the flare, suggesting a new component of radiation. The polarization variation during the rise of the flare suggests the same. The limits on the source size place it most reasonably in the jet of the secondary BH. We then ask why we have not seen this phenomenon before. We show that OJ287 was never before observed with sufficient sensitivity on the night when the flare should have happened according to the binary model. We also study the probability that this flare is just an oversized example of intraday variability using the Krakow data set of intense monitoring between 2015 and 2023. We find that the occurrence of a flare of this size and rapidity is unlikely. In machine-readable Tables 1 and 2, we give the full orbit-linked historical light curve of OJ287 as well as the dense monitoring sample of Krakow.
ESA/ACT Science Coffee: Diego Blas - Gravitational wave detection with orbita...Advanced-Concepts-Team
Presentation in the Science Coffee of the Advanced Concepts Team of the European Space Agency on the 07.06.2024.
Speaker: Diego Blas (IFAE/ICREA)
Title: Gravitational wave detection with orbital motion of Moon and artificial
Abstract:
In this talk I will describe some recent ideas to find gravitational waves from supermassive black holes or of primordial origin by studying their secular effect on the orbital motion of the Moon or satellites that are laser ranged.
Mending Clothing to Support Sustainable Fashion_CIMaR 2024.pdfSelcen Ozturkcan
Ozturkcan, S., Berndt, A., & Angelakis, A. (2024). Mending clothing to support sustainable fashion. Presented at the 31st Annual Conference by the Consortium for International Marketing Research (CIMaR), 10-13 Jun 2024, University of Gävle, Sweden.
Describing and Interpreting an Immersive Learning Case with the Immersion Cub...Leonel Morgado
Current descriptions of immersive learning cases are often difficult or impossible to compare. This is due to a myriad of different options on what details to include, which aspects are relevant, and on the descriptive approaches employed. Also, these aspects often combine very specific details with more general guidelines or indicate intents and rationales without clarifying their implementation. In this paper we provide a method to describe immersive learning cases that is structured to enable comparisons, yet flexible enough to allow researchers and practitioners to decide which aspects to include. This method leverages a taxonomy that classifies educational aspects at three levels (uses, practices, and strategies) and then utilizes two frameworks, the Immersive Learning Brain and the Immersion Cube, to enable a structured description and interpretation of immersive learning cases. The method is then demonstrated on a published immersive learning case on training for wind turbine maintenance using virtual reality. Applying the method results in a structured artifact, the Immersive Learning Case Sheet, that tags the case with its proximal uses, practices, and strategies, and refines the free text case description to ensure that matching details are included. This contribution is thus a case description method in support of future comparative research of immersive learning cases. We then discuss how the resulting description and interpretation can be leveraged to change immersion learning cases, by enriching them (considering low-effort changes or additions) or innovating (exploring more challenging avenues of transformation). The method holds significant promise to support better-grounded research in immersive learning.
The cost of acquiring information by natural selectionCarl Bergstrom
This is a short talk that I gave at the Banff International Research Station workshop on Modeling and Theory in Population Biology. The idea is to try to understand how the burden of natural selection relates to the amount of information that selection puts into the genome.
It's based on the first part of this research paper:
The cost of information acquisition by natural selection
Ryan Seamus McGee, Olivia Kosterlitz, Artem Kaznatcheev, Benjamin Kerr, Carl T. Bergstrom
bioRxiv 2022.07.02.498577; doi: https://doi.org/10.1101/2022.07.02.498577
The binding of cosmological structures by massless topological defectsSérgio Sacani
Assuming spherical symmetry and weak field, it is shown that if one solves the Poisson equation or the Einstein field
equations sourced by a topological defect, i.e. a singularity of a very specific form, the result is a localized gravitational
field capable of driving flat rotation (i.e. Keplerian circular orbits at a constant speed for all radii) of test masses on a thin
spherical shell without any underlying mass. Moreover, a large-scale structure which exploits this solution by assembling
concentrically a number of such topological defects can establish a flat stellar or galactic rotation curve, and can also deflect
light in the same manner as an equipotential (isothermal) sphere. Thus, the need for dark matter or modified gravity theory is
mitigated, at least in part.
2. Introduction
• membrane-bound organelle (eukaryotic
only!)
• Each cell contains hundreds to thousands of
mitochondria.
• Site of Krebs cycle and oxidative
phosphorylation (the electron transport
chain, or respiratory chain).
• Power House – Synthesis of ATP
• Two membranes: outer and inner.
• Folds of the inner membrane, where most
of oxidative phosphorylation occurs, are
called cristae.
• Inside inner membrane = matrix
• Between membranes = intermembrane
space
• Mitochondrial DNA is inside the inner
membrane.
3. Mitochondria
•Analysis of mitochondrial Genome helps in
•Understanding the molecular basis of cytoplasmic
mutations
•Susceptibility to systemic insecticides
•Sensitivity to fungal toxins
4. Endosymbiont Hypothesis
•Endosymbiont hypothesis: originally proposed in
1883 by Andreas Schimper, but extended by Lynn
Margulis in the 1980s
•Mitochondrial ribosomal RNA genes and other genes
show that the original organism was in the alpha-
proteobacterial family (similar to nitrogen-fixing
bacteria)
5. Endosymbiont Hypothesis
• Evidence
• Mitochondria have their own DNA (circular)
• The inner membrane is more similar to prokaryotic membranes than to
eukaryotic.
• By the hypothesis, the inner membrane was the original
prokaryotic membrane and the outer membrane was from the
primitive eukaryote that swallowed it.
• Mitochondria make their own ribosomes, which are of the prokaryotic 70s
type, not the eukaryotic 80s type.
• Mitochondria are sensitive to many bacterial inhibitors that don’t affect the
rest of the eukaryotic cell, such as streptomycin, chloramphenicol, rifampicin.
• Mitochondrial protein synthesis starts with n-formyl methionine, as in the
bacteria but unlike eukaryotes.
6. •Most of the original bacterial genes have
migrated into the nucleus.
•Eukaryotes that lack mitochondria generally
have some mitochondrial genes in their
nucleus, evidence that their ancestors had
mitochondria that were lost during evolution.
7. Endosymbiont Hypothesis
This is actually a secondary endosymbiosis: the largest cell is engulfing a photosynthetic
eukaryote, which already contains chloroplasts.
8. Mitochondrial Function
Krebs cycle:
• Pyruvate, the product of glycolysis, is produced in the
cytoplasm.
• It is transported into the mitochondrial matrix (inside the
inner membrane).
• There, it is converted into acetyl CoA.
• Fatty acids, from the breakdown of lipids, are also
transported into the matrix and converted to acetyl CoA.
• The Krebs cycle then converts acetyl CoA into carbon dioxide
and high energy electrons. The high energy electrons are
carried by NADH and FADH2.
9. Electron Transport:
• The high energy electrons are removed from NADH and
FADH2, and passed through three protein complexes
embedded in the inner membrane.
• Each complex uses some of the electrons’ energy to pump H+
ions out of the matrix into the intermembrane space.
• The final protein complex gives the electrons to oxygen,
converting it to water.
• The H+ ions come back into the matrix, down the
concentration gradient, through a fourth complex, ATP
synthase (also called ATPase), which uses their energy to
generate ATP from ADP and inorganic phosphate.
• In brown fat, the synthesis of ATP is uncoupled from the flow
of H+ ions back into the matrix. The H+ ions flow through a
protein called thermogenin, and not through the ATPase. The
energy is converted into heat: the primary way we keep warm
in cold weather.
11. Size and organization
•Plant Mt.DNA – Much larger and more complex
•Size : 200 – 2500 Kb
•Analyses of cucurbit mtDNAs
• seven-fold range in genome size within this family,
• 330 kb in watermelon to approximately 2500 kb in muskmelon
•Changes in size occurs very rapidly
•Closely related species will have quite different
mitochondrial genome size
•Physical form of genome is not well understood
• Circular DNA
• Mitochondrial plasmid DNA
• Collection of circle- Exist as a population of subgenomic circles
12. Organization – Key feautures
Several general features of higher plant mitochondrial genomes
1. The genomes are larger than those from mammals and fungi.
2. Organized as multiple circular molecules, with conversion of circle types
mediated by recombination between repeated sequences.
3. Mitochondrial genomes from closely related species are highly conserved in
primary sequence, but vary greatly in linear gene order.
4. Chloroplast DNA sequences are found in mitochondrial DNA.
5. In addition to high molecular weight mtDNA, plasmid-like molecules are
present in mitochondria.
13. Chloroplast sequences in mitochondrial genome
•Sequences highly homologous to chloroplast DNA are
present in the mitochondrial genomes of many species
•Maize has inverted repeat sequences(12 Kb)of
chloroplast genome in mitochondrial genome
• Carries several tRNA and 16s rRNA sequences
•Sequence homologous to the chloroplast ribulose-l ,5-
bisphosphate carboxylase large subunit gene was also
found in mtDNA
•These studies demonstrate that DNA transfer from
chloroplasts to mitochondria is common in higher plants
and that most of the events are recent
•No direct evidence on mechanism
14. GENE CONTENT. STRUCTURE AND EXPRESSION
Special features of mitochondrial genome
• Ribosomal protein gene, rRNA, tRNA for mitochondrial translation system
• Proteins in ETC and ATP ase complex
• rRNA arrangement pattern is similar in yeast
• 26s rRNA – separated from 18s and 5s rRNA segments by a long distance
• Intron less sequences : COI(cytochrome c oxidase), COB gene
(apocytochrome B)
• Mitochondrial tRNA is diverse – differs in structure from prokaryotes and
eukaryotes
• Mitochondrial Ribosomes – 77-78s units in plants
• No Polyadenylation
• Multiple Termination, Initiation and Processing sites
• Genetic code is also different
• Eg: CGG – Tryptophan (plants) {TGG- Mammals, TGC/UGA- yeast}
15. Mitochondrial genes
Genes for respiratory chain
functions
• Complex I, the NADH-dehydrogenase
(nine polypeptides, genes nad1–7, nad4L
and nad9) –
The NAD10 subunit of complex I,
which is encoded mitochondrially in some
fungi and algae.
• Complex II, the succinate dehydrogenase
(1 subunit, sdh4)
Genes for three subunits of complex II
are found in the mitochondrial genomes of
some red and brown algae, two units in M.
polymorpha, but only one in Arabidopsis.
• Complex III, the cytochrome-c reductase
(1 polypeptide, cytb)
• Complex IV, the cytochrome-c oxidase
(three subunits, cox1–3).
16. Mitochondrial DNA replication
• Replication have been identified by sequence homology and from proteomic
data.
• Among those, plant organellar DNA polymerases were identified by their
similarities to the known mitochondrial DNA polymerase of animals and
yeast.
• In A. thaliana, there are two organellar DNA polymerases, Pol1A and Pol1B,
which are dual targeted to both mitochondria and plastids and which are
apparently redundant in their functions .
• Individually, each of them is dispensable, because the mutants show no
visible phenotypes, apart from a small reduction in mtDNA and chloroplast
DNA (cpDNA) copy numbers.
• Conversely, the double mutant is not viable, showing that the two
polymerases are redundant for organellar genome replication.