Podcast
Questions and Answers
If we were to write out all of the DNA base pairs in a human cell in a single line using this font, how far would the line stretch?
If we were to write out all of the DNA base pairs in a human cell in a single line using this font, how far would the line stretch?
- From London to Tokyo
- Around the world
- From Miami to Fairbanks, Alaska (correct)
- From New York City to Los Angeles
How many base pairs are present in a single human cell?
How many base pairs are present in a single human cell?
- 1.6 billion
- 23
- 46
- 3.2 billion (correct)
What is the primary focus of this particular lecture?
What is the primary focus of this particular lecture?
- The central dogma of molecular biology (correct)
- The function of RNA
- The structure of proteins
- The process of DNA replication
How many chromosomes are found in a normal human cell?
How many chromosomes are found in a normal human cell?
Which of the following is an accurate statement about the DNA in a human cell?
Which of the following is an accurate statement about the DNA in a human cell?
What is the primary difference between the organization of DNA in different organisms?
What is the primary difference between the organization of DNA in different organisms?
What is the source of one chromosome in each pair in a human cell?
What is the source of one chromosome in each pair in a human cell?
What does the term 'base pair' refer to in the context of DNA?
What does the term 'base pair' refer to in the context of DNA?
What is the approximate length of DNA in a human cell if it were to be stretched out end to end?
What is the approximate length of DNA in a human cell if it were to be stretched out end to end?
What is the diameter of the nucleus of a human cell?
What is the diameter of the nucleus of a human cell?
How many times smaller is the diameter of the nucleus compared to the length of the DNA molecules?
How many times smaller is the diameter of the nucleus compared to the length of the DNA molecules?
What is the process called when DNA is compacted to fit inside the nucleus?
What is the process called when DNA is compacted to fit inside the nucleus?
What are the protein clusters called that DNA wraps around during the initial level of compaction?
What are the protein clusters called that DNA wraps around during the initial level of compaction?
What is the name of the structure formed when DNA winds around histone proteins?
What is the name of the structure formed when DNA winds around histone proteins?
During which stage of cell division do chromosomes become highly condensed?
During which stage of cell division do chromosomes become highly condensed?
What is the term used to describe the entirety of a single double-stranded DNA molecule in its most condensed form?
What is the term used to describe the entirety of a single double-stranded DNA molecule in its most condensed form?
What term describes the state of DNA during most of the cell cycle, when it is not undergoing mitosis?
What term describes the state of DNA during most of the cell cycle, when it is not undergoing mitosis?
What is the term used to describe the number of copies of each chromosome present within a cell?
What is the term used to describe the number of copies of each chromosome present within a cell?
What is the ploidy level of most human cells?
What is the ploidy level of most human cells?
What process reduces the chromosome number in half, leading to cells with one copy of each chromosome?
What process reduces the chromosome number in half, leading to cells with one copy of each chromosome?
What is an example of a ploidy level that is commonly found in plants, but not in humans?
What is an example of a ploidy level that is commonly found in plants, but not in humans?
What is the term used to describe the process of regulating how DNA is packaged and how this can affect gene expression?
What is the term used to describe the process of regulating how DNA is packaged and how this can affect gene expression?
What is the term used to describe changes in the packaging of DNA over time or depending on external factors?
What is the term used to describe changes in the packaging of DNA over time or depending on external factors?
What analogy is used in the content to explain how DNA is packaged within the nucleus?
What analogy is used in the content to explain how DNA is packaged within the nucleus?
What is the main function of the H1 histone?
What is the main function of the H1 histone?
Which of the following is the most common structure of chromatin in the human body?
Which of the following is the most common structure of chromatin in the human body?
What is the approximate length of DNA that is wrapped around a nucleosome?
What is the approximate length of DNA that is wrapped around a nucleosome?
During which stage of mitosis do the solenoids compact further to form chromosomes?
During which stage of mitosis do the solenoids compact further to form chromosomes?
What is the name of the proteins that aid in the further compaction of solenoids into chromosomes during mitosis?
What is the name of the proteins that aid in the further compaction of solenoids into chromosomes during mitosis?
What is the average spacing between nucleosomes on a DNA strand?
What is the average spacing between nucleosomes on a DNA strand?
The text mentions that there is a particular region where nucleosomes are almost always found. Where is this region?
The text mentions that there is a particular region where nucleosomes are almost always found. Where is this region?
What are the two main functions of the N-terminal tails of the histones?
What are the two main functions of the N-terminal tails of the histones?
What does the text suggest about the formation of solenoids?
What does the text suggest about the formation of solenoids?
Which of the following is NOT a factor that influences the localization of nucleosomes on a DNA strand?
Which of the following is NOT a factor that influences the localization of nucleosomes on a DNA strand?
What does the statement "histones prefer certain stretches of DNA over other stretches of DNA" imply?
What does the statement "histones prefer certain stretches of DNA over other stretches of DNA" imply?
What is the significance of the "beads on a string" structure in the context of DNA packaging?
What is the significance of the "beads on a string" structure in the context of DNA packaging?
Why are electrostatic interactions or ionic bonding favored for histone binding compared to specific DNA sequences?
Why are electrostatic interactions or ionic bonding favored for histone binding compared to specific DNA sequences?
What is the role of histone tails in the formation of the 30 nanometer fiber?
What is the role of histone tails in the formation of the 30 nanometer fiber?
What is the significance of the relatively constant spacing between nucleosomes on a DNA strand?
What is the significance of the relatively constant spacing between nucleosomes on a DNA strand?
What is the approximate length of DNA wrapped around a single histone complex?
What is the approximate length of DNA wrapped around a single histone complex?
Why is the "rope analogy" used to explain the formation of solenoids?
Why is the "rope analogy" used to explain the formation of solenoids?
What is the primary function of the DNAse enzyme utilized in the nucleosome digestion assay?
What is the primary function of the DNAse enzyme utilized in the nucleosome digestion assay?
What is the approximate spacing between two adjacent nucleosomes?
What is the approximate spacing between two adjacent nucleosomes?
Which of the following proteins is involved in the formation of the 30 nanometer fiber?
Which of the following proteins is involved in the formation of the 30 nanometer fiber?
How does the 30 nanometer fiber achieve its diameter?
How does the 30 nanometer fiber achieve its diameter?
What is the primary role of the unstructured and terminal tails of histones?
What is the primary role of the unstructured and terminal tails of histones?
Why is it important for histones to bind DNA with some degree of flexibility rather than precise specificity?
Why is it important for histones to bind DNA with some degree of flexibility rather than precise specificity?
What is the main reason why it is not feasible to define histone binding events based on specific DNA sequences?
What is the main reason why it is not feasible to define histone binding events based on specific DNA sequences?
Which of the following characteristics of histone binding allows for flexibility in its interaction with DNA?
Which of the following characteristics of histone binding allows for flexibility in its interaction with DNA?
What is the main reason why the nucleosome digestion assay is a valuable tool for investigating histone binding?
What is the main reason why the nucleosome digestion assay is a valuable tool for investigating histone binding?
Why is the DNA sequence wrapped around a histone considered protected from DNase digestion?
Why is the DNA sequence wrapped around a histone considered protected from DNase digestion?
What is the main difference between the 170 base pair fragment and the 205 base pair fragment observed in the nucleosome digestion assay?
What is the main difference between the 170 base pair fragment and the 205 base pair fragment observed in the nucleosome digestion assay?
What type of interaction primarily contributes to the formation of the 30 nanometer fiber?
What type of interaction primarily contributes to the formation of the 30 nanometer fiber?
What is the main advantage of the 30 nanometer fiber formation in terms of DNA compaction?
What is the main advantage of the 30 nanometer fiber formation in terms of DNA compaction?
What is the primary outcome associated with DNA methylation and acetylation?
What is the primary outcome associated with DNA methylation and acetylation?
DNA methylation and histone acetylation are primarily involved in which biological concept?
DNA methylation and histone acetylation are primarily involved in which biological concept?
Which process is directly supported by acetylation in relation to DNA?
Which process is directly supported by acetylation in relation to DNA?
How do DNA methylation and histone acetylation affect gene expression?
How do DNA methylation and histone acetylation affect gene expression?
What is the relationship between heterochromia information and DNA methylation?
What is the relationship between heterochromia information and DNA methylation?
What is the effect of adding H1 histone to activated chromatin?
What is the effect of adding H1 histone to activated chromatin?
What is the relationship between chromatin condensation and transcription levels?
What is the relationship between chromatin condensation and transcription levels?
In the absence of transcription factors, what happens to DNA sequences in the presence of histones?
In the absence of transcription factors, what happens to DNA sequences in the presence of histones?
What mechanism allows for the transition of a gene from an active to an inactive state?
What mechanism allows for the transition of a gene from an active to an inactive state?
What type of chromatin is associated with tightly packed DNA and lower transcription rates?
What type of chromatin is associated with tightly packed DNA and lower transcription rates?
Which factor directly prevents histones from binding to actively transcribed DNA?
Which factor directly prevents histones from binding to actively transcribed DNA?
Why might some genes be inactive in a particular cell type, such as skin cells?
Why might some genes be inactive in a particular cell type, such as skin cells?
What happens to transcription when all transcription factors and RNA polymerase are present in the presence of H1 histone?
What happens to transcription when all transcription factors and RNA polymerase are present in the presence of H1 histone?
What would be expected in a region of DNA with heterochromatin?
What would be expected in a region of DNA with heterochromatin?
How can chromatin structure influence gene expression levels?
How can chromatin structure influence gene expression levels?
What is a major implication of chromatin structure on gene regulation?
What is a major implication of chromatin structure on gene regulation?
Which of the following best describes active chromatin during transcription?
Which of the following best describes active chromatin during transcription?
What allows certain genes to be expressed only during specific developmental stages?
What allows certain genes to be expressed only during specific developmental stages?
What is the primary effect of lysine acetylation on DNA packaging?
What is the primary effect of lysine acetylation on DNA packaging?
Histone methylation can lead to which of the following outcomes?
Histone methylation can lead to which of the following outcomes?
What role do promoter domain-containing proteins play in transcription regulation?
What role do promoter domain-containing proteins play in transcription regulation?
What is one possible consequence of histone phosphorylation?
What is one possible consequence of histone phosphorylation?
What can initiate a cascade of histone modifications?
What can initiate a cascade of histone modifications?
How many methyl groups can be added to a lysine residue during histone methylation?
How many methyl groups can be added to a lysine residue during histone methylation?
Which enzyme is responsible for adding methyl groups to histones?
Which enzyme is responsible for adding methyl groups to histones?
What is the main action of histone demethylation?
What is the main action of histone demethylation?
What does the recruitment of chromo domain proteins indicate?
What does the recruitment of chromo domain proteins indicate?
The effect of post-translational modifications on histones is primarily dependent on what factor?
The effect of post-translational modifications on histones is primarily dependent on what factor?
What type of charge does the addition of a phosphate group provide to histones?
What type of charge does the addition of a phosphate group provide to histones?
What commonality exists between histone acetylation and methylation in terms of protein recruitment?
What commonality exists between histone acetylation and methylation in terms of protein recruitment?
What mechanism allows for the propagation of methylation along DNA?
What mechanism allows for the propagation of methylation along DNA?
What effect does heterochromatin have on transcription?
What effect does heterochromatin have on transcription?
Which of the following post-translational modifications is most likely to occur on lysine residues?
Which of the following post-translational modifications is most likely to occur on lysine residues?
How does acetylation affect the charge of lysine residues?
How does acetylation affect the charge of lysine residues?
What is the primary role of post-translational modifications on histone tails?
What is the primary role of post-translational modifications on histone tails?
What happens to lysine's charge after it undergoes acetylation?
What happens to lysine's charge after it undergoes acetylation?
Which modification can add a negative charge to histone tails?
Which modification can add a negative charge to histone tails?
What is meant by the term 'reversible' in the context of post-translational modifications?
What is meant by the term 'reversible' in the context of post-translational modifications?
What type of interaction is weakened when acetyl groups are added to lysine residues?
What type of interaction is weakened when acetyl groups are added to lysine residues?
What role do histone acetyl transferases play in histone modification?
What role do histone acetyl transferases play in histone modification?
What consequence does reduced positive charge on histones have for gene transcription?
What consequence does reduced positive charge on histones have for gene transcription?
Which modification is represented by orange triangles in the described histone modifications?
Which modification is represented by orange triangles in the described histone modifications?
How are the interactions between acetylated histones and DNA characterized?
How are the interactions between acetylated histones and DNA characterized?
What typically happens to histones after they lose an acetyl group?
What typically happens to histones after they lose an acetyl group?
In terms of chromatin regulation, what is the impact of acetylated histones?
In terms of chromatin regulation, what is the impact of acetylated histones?
What is a key feature of less densely packed chromatin?
What is a key feature of less densely packed chromatin?
Which type of chromatin is characterized by more densely packed regions?
Which type of chromatin is characterized by more densely packed regions?
What does heterochromatin typically contain?
What does heterochromatin typically contain?
Why is it beneficial for euchromatin to be organized closely together?
Why is it beneficial for euchromatin to be organized closely together?
What is the purpose of the methodology known as FISH?
What is the purpose of the methodology known as FISH?
What can overlapping regions of DNA in FISH indicate?
What can overlapping regions of DNA in FISH indicate?
What is the effect of increased chromatin density on gene expression?
What is the effect of increased chromatin density on gene expression?
Which regions of the genome are often found in heterochromatin?
Which regions of the genome are often found in heterochromatin?
What is the main characteristic of the nucleoplasm in relation to chromatin?
What is the main characteristic of the nucleoplasm in relation to chromatin?
Which is true about the physical organization of chromosomes within the nucleus?
Which is true about the physical organization of chromosomes within the nucleus?
What does the term 'exclusion zone' refer to?
What does the term 'exclusion zone' refer to?
How does compacting heterochromatin contribute to DNA stability?
How does compacting heterochromatin contribute to DNA stability?
How is the organization of chromatin related to gene expression?
How is the organization of chromatin related to gene expression?
What happens to chromatin during transcription?
What happens to chromatin during transcription?
What type of modification is most likely to occur on serine residues within histones?
What type of modification is most likely to occur on serine residues within histones?
How does phosphorylation of serine ten affect lysine 14 in histones?
How does phosphorylation of serine ten affect lysine 14 in histones?
What effect does acetylation of histones generally have on chromatin structure?
What effect does acetylation of histones generally have on chromatin structure?
Which enzyme is primarily responsible for adding methyl groups directly to DNA?
Which enzyme is primarily responsible for adding methyl groups directly to DNA?
How does methylation of cytosine residues in DNA impact gene expression?
How does methylation of cytosine residues in DNA impact gene expression?
In the context of histone modifications, what is the potential consequence of acetylating lysine residues?
In the context of histone modifications, what is the potential consequence of acetylating lysine residues?
What is the relationship between histone phosphorylation at serine ten and lysine nine?
What is the relationship between histone phosphorylation at serine ten and lysine nine?
Which histone modification is associated with promoting heterochromatin formation?
Which histone modification is associated with promoting heterochromatin formation?
What role do DNA methyl-binding proteins play in gene regulation?
What role do DNA methyl-binding proteins play in gene regulation?
Which of the following is NOT a post-translational modification typically found on histones?
Which of the following is NOT a post-translational modification typically found on histones?
What signifies the complexity of histone modification interactions?
What signifies the complexity of histone modification interactions?
What is the primary function of histone acetyltransferase enzymes?
What is the primary function of histone acetyltransferase enzymes?
Which post-translational modification can inhibit the phosphorylation of serine ten in histones?
Which post-translational modification can inhibit the phosphorylation of serine ten in histones?
Which nucleotide is primarily associated with direct methylation in DNA regulation?
Which nucleotide is primarily associated with direct methylation in DNA regulation?
What is the primary function of the unstructured N-terminal tail of histone proteins?
What is the primary function of the unstructured N-terminal tail of histone proteins?
According to the lecture, what is the significance of the high conservation of core histone proteins across eukaryotic organisms?
According to the lecture, what is the significance of the high conservation of core histone proteins across eukaryotic organisms?
Why are histone proteins able to bind to DNA along the entire 3.2 billion base sequence?
Why are histone proteins able to bind to DNA along the entire 3.2 billion base sequence?
How many histone proteins are present in a single nucleosome?
How many histone proteins are present in a single nucleosome?
What type of interaction is likely to occur between an arginine residue in a histone protein and the DNA backbone?
What type of interaction is likely to occur between an arginine residue in a histone protein and the DNA backbone?
Which of the following amino acids would you expect to be preferentially found in histones?
Which of the following amino acids would you expect to be preferentially found in histones?
Why are histone proteins considered to be highly conserved across eukaryotic organisms?
Why are histone proteins considered to be highly conserved across eukaryotic organisms?
What is the approximate number of base pairs of DNA that are wrapped around a single nucleosome?
What is the approximate number of base pairs of DNA that are wrapped around a single nucleosome?
Which histone protein is not part of the core nucleosome structure?
Which histone protein is not part of the core nucleosome structure?
Which of the following statements about the interactions between histone proteins and DNA is not accurate?
Which of the following statements about the interactions between histone proteins and DNA is not accurate?
What is the primary structure of the histone proteins?
What is the primary structure of the histone proteins?
How many copies of each of the core histones are present in a single nucleosome?
How many copies of each of the core histones are present in a single nucleosome?
What is the main reason why the amino acid arginine is preferentially found in histones?
What is the main reason why the amino acid arginine is preferentially found in histones?
Why are histone proteins considered to be important for gene regulation?
Why are histone proteins considered to be important for gene regulation?
Which of the following is NOT a characteristic of nucleosomes?
Which of the following is NOT a characteristic of nucleosomes?
What is the main reason DNA needs to be packaged?
What is the main reason DNA needs to be packaged?
What is a major consequence of DNA rearrangements?
What is a major consequence of DNA rearrangements?
How does DNA packaging protect against mutations?
How does DNA packaging protect against mutations?
What is the role of histones in DNA packaging?
What is the role of histones in DNA packaging?
Why is DNA packaging described as an evolutionary conserved mechanism?
Why is DNA packaging described as an evolutionary conserved mechanism?
How does the packaging of DNA in prokaryotes compare to that in eukaryotes?
How does the packaging of DNA in prokaryotes compare to that in eukaryotes?
What is the approximate length of a human chromosome compared to its corresponding nucleus?
What is the approximate length of a human chromosome compared to its corresponding nucleus?
In the context of DNA packaging, what does the term "supercoiling" refer to?
In the context of DNA packaging, what does the term "supercoiling" refer to?
What is the significance of the observation that histones H3 and H4 can be cross-linked in solution?
What is the significance of the observation that histones H3 and H4 can be cross-linked in solution?
Based on the passage, what is the general approach scientists use to understand complex biological processes?
Based on the passage, what is the general approach scientists use to understand complex biological processes?
Why is DNA packaging relevant to the study of cancer?
Why is DNA packaging relevant to the study of cancer?
What is the primary function of the histone proteins in the context of DNA packaging?
What is the primary function of the histone proteins in the context of DNA packaging?
What does the term "evolutionarily conserved" signify in the context of DNA packaging?
What does the term "evolutionarily conserved" signify in the context of DNA packaging?
What is the main function of the compaction of DNA within bacterial cells?
What is the main function of the compaction of DNA within bacterial cells?
Why is the analogy of a ball of yarn used to describe DNA packaging?
Why is the analogy of a ball of yarn used to describe DNA packaging?
Which of the following is NOT mentioned as a benefit of DNA packaging?
Which of the following is NOT mentioned as a benefit of DNA packaging?
What is the primary reason why AT-rich sequences are able to bind better to nucleosomes than GC-rich sequences?
What is the primary reason why AT-rich sequences are able to bind better to nucleosomes than GC-rich sequences?
What is the name of the molecule that helps histones assemble?
What is the name of the molecule that helps histones assemble?
In the experiment described, what is the effect of increasing the concentration of core histones on transcription levels?
In the experiment described, what is the effect of increasing the concentration of core histones on transcription levels?
Which of the following is NOT a factor contributing to the variability in nucleosome positioning?
Which of the following is NOT a factor contributing to the variability in nucleosome positioning?
What is the significance of the 100% activity level used in the experiment as a reference point?
What is the significance of the 100% activity level used in the experiment as a reference point?
Which of the following is a valid explanation for the observed decrease in transcription levels when core histones are added?
Which of the following is a valid explanation for the observed decrease in transcription levels when core histones are added?
What is the primary reason for the decrease in transcription levels as the concentration of core histones increases?
What is the primary reason for the decrease in transcription levels as the concentration of core histones increases?
Which two hypotheses are proposed to explain the mechanism of transcription inhibition by histones?
Which two hypotheses are proposed to explain the mechanism of transcription inhibition by histones?
In the experiment, what is the purpose of including the lane with poly glutamate but no histones?
In the experiment, what is the purpose of including the lane with poly glutamate but no histones?
Which of the following experiments would provide strong evidence that histones directly inhibit RNA polymerase activity?
Which of the following experiments would provide strong evidence that histones directly inhibit RNA polymerase activity?
What is the main point that the content is trying to explain regarding the relationship between histones and transcription?
What is the main point that the content is trying to explain regarding the relationship between histones and transcription?
Which statement best summarizes the analogy used to explain the effect of histones on transcription levels?
Which statement best summarizes the analogy used to explain the effect of histones on transcription levels?
In the context of the experiment, what is considered the most physiologically relevant condition?
In the context of the experiment, what is considered the most physiologically relevant condition?
Which statement best describes the overall relationship between DNA packaging and gene expression?
Which statement best describes the overall relationship between DNA packaging and gene expression?
Based on the experiment, what can we conclude about the relationship between histone concentration and transcription levels?
Based on the experiment, what can we conclude about the relationship between histone concentration and transcription levels?
How does the presence of histone proteins contribute to the regulation of gene expression?
How does the presence of histone proteins contribute to the regulation of gene expression?
What is the purpose of the restriction enzyme assay described in the content?
What is the purpose of the restriction enzyme assay described in the content?
What key difference distinguishes a restriction enzyme from a general DNA digesting enzyme?
What key difference distinguishes a restriction enzyme from a general DNA digesting enzyme?
Based on the restriction enzyme assay results described in the content, what can be concluded about the relationship between nucleosomes and transcription?
Based on the restriction enzyme assay results described in the content, what can be concluded about the relationship between nucleosomes and transcription?
Which of the following statements accurately describes the role of histone H1 in chromatin structure and gene expression?
Which of the following statements accurately describes the role of histone H1 in chromatin structure and gene expression?
What is the main conclusion drawn from the observations related to histone H1 and gene expression?
What is the main conclusion drawn from the observations related to histone H1 and gene expression?
What is the primary function of transcription factors in the process of gene expression?
What is the primary function of transcription factors in the process of gene expression?
Which of the following best describes the role of RNA polymerase in gene expression?
Which of the following best describes the role of RNA polymerase in gene expression?
Why does the content mention that nucleosomes cover approximately 75% of the DNA in a particular DNA molecule?
Why does the content mention that nucleosomes cover approximately 75% of the DNA in a particular DNA molecule?
What is the primary takeaway of the passage regarding the relationship between nucleosomes and transcription?
What is the primary takeaway of the passage regarding the relationship between nucleosomes and transcription?
The content mentions that transcription either occurs or does not occur for certain sites in purified DNA. What is the primary factor responsible for this variability?
The content mentions that transcription either occurs or does not occur for certain sites in purified DNA. What is the primary factor responsible for this variability?
In the context of the passage, what does the term 'repressed chromatin' refer to?
In the context of the passage, what does the term 'repressed chromatin' refer to?
What is the most likely reason why a nucleosome might be removed from the start site of a gene?
What is the most likely reason why a nucleosome might be removed from the start site of a gene?
What is the significance of the fact that nucleosomes cover approximately 75% of the DNA in a particular DNA molecule? (Select all that apply.)
What is the significance of the fact that nucleosomes cover approximately 75% of the DNA in a particular DNA molecule? (Select all that apply.)
What is the main focus of the follow-up experiments described in the content?
What is the main focus of the follow-up experiments described in the content?
Why are transcription factors important for the regulation of gene expression? (Select all that apply.)
Why are transcription factors important for the regulation of gene expression? (Select all that apply.)
Flashcards
Central Dogma
Central Dogma
The process of DNA being transcribed to RNA, then translated to protein.
DNA Structure
DNA Structure
DNA consists of two strands forming a double helix made of nucleotides.
Nucleotides
Nucleotides
The building blocks of DNA and RNA, consisting of a sugar, phosphate, and a base.
Human Chromosomes
Human Chromosomes
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Base Pairs
Base Pairs
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Genome Length
Genome Length
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Chromosome Function
Chromosome Function
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DNA Interaction
DNA Interaction
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Nucleus Diameter
Nucleus Diameter
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DNA Length in Cells
DNA Length in Cells
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Nucleosomes
Nucleosomes
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Solenoid Structure
Solenoid Structure
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Chromosomes
Chromosomes
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Chromatin
Chromatin
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Diploid Cells
Diploid Cells
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Haploid Cells
Haploid Cells
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Mitosis Stages
Mitosis Stages
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Interphase
Interphase
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Triploid Cells
Triploid Cells
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Chromosome Numbers
Chromosome Numbers
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DNA Packaging
DNA Packaging
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Chromosome vs Chromatin
Chromosome vs Chromatin
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Nucleus
Nucleus
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DNA Supercoiling
DNA Supercoiling
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Mutation Protection
Mutation Protection
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Cellular Organization
Cellular Organization
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Chromosomal Rearrangement
Chromosomal Rearrangement
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Histones
Histones
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Supercoiling
Supercoiling
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Prokaryotic Compaction
Prokaryotic Compaction
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Eukaryotic Compaction
Eukaryotic Compaction
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Mutagens
Mutagens
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DNA Double Strand Break
DNA Double Strand Break
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Evolutionary Conserved Mechanism
Evolutionary Conserved Mechanism
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Ball of Yarn Analogy
Ball of Yarn Analogy
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Observation of Histones
Observation of Histones
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H2A, H2B, H3, H4
H2A, H2B, H3, H4
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Cross-linking Proteins
Cross-linking Proteins
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Histone Complex
Histone Complex
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H1 Histone
H1 Histone
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Histone Conservation
Histone Conservation
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Histone Interaction
Histone Interaction
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Amino Acids in Histones
Amino Acids in Histones
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Histone N-terminal Tail
Histone N-terminal Tail
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Histone Duplication
Histone Duplication
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Core Histones
Core Histones
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DNA Backbone Charge
DNA Backbone Charge
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Eukaryotic Organisms
Eukaryotic Organisms
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DNA-Sequencing Interaction
DNA-Sequencing Interaction
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Centromere & Telomere
Centromere & Telomere
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Protein Function Significance
Protein Function Significance
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Nucleosome Positioning
Nucleosome Positioning
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DNA Flexibility
DNA Flexibility
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A-T Rich Sequences
A-T Rich Sequences
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Hydrogen Bonding in Base Pairs
Hydrogen Bonding in Base Pairs
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Transcription Factors
Transcription Factors
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Role of Histones
Role of Histones
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Effect of Histones on Transcription
Effect of Histones on Transcription
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RNA Polymerase Function
RNA Polymerase Function
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Histone Control in Transcription
Histone Control in Transcription
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Transcription Levels Measurement
Transcription Levels Measurement
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Polyglutamate Role
Polyglutamate Role
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Histone Ratios in Experiments
Histone Ratios in Experiments
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Hypothesis on RNA Polymerase
Hypothesis on RNA Polymerase
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Nucleosome Binding Sites
Nucleosome Binding Sites
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Chromatin Regulation
Chromatin Regulation
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N-terminal tails
N-terminal tails
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Nucleosome interaction
Nucleosome interaction
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30 nanometer fiber
30 nanometer fiber
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Condensin proteins
Condensin proteins
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Histone binding preference
Histone binding preference
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Nucleosome spacing
Nucleosome spacing
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Transcription start site
Transcription start site
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Disordered aggregates
Disordered aggregates
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DNA wrapping
DNA wrapping
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Cryo-EM data
Cryo-EM data
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Chromatin organization
Chromatin organization
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Euchromatin vs Heterochromatin
Euchromatin vs Heterochromatin
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Histone Binding Specificity
Histone Binding Specificity
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Nucleosome Composition
Nucleosome Composition
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DNA Digestion Assay
DNA Digestion Assay
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Protected DNA Sections
Protected DNA Sections
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170 Base Pairs
170 Base Pairs
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205 Base Pairs
205 Base Pairs
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Histone H1 Role
Histone H1 Role
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Electrostatic Interactions
Electrostatic Interactions
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Protein-DNA Interactions
Protein-DNA Interactions
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Nucleosomal Protection
Nucleosomal Protection
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Sizing DNA Fragments
Sizing DNA Fragments
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Histone Complex Interactions
Histone Complex Interactions
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Geometry of DNA Wrapping
Geometry of DNA Wrapping
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DNA Methylation
DNA Methylation
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Histone Acetylation
Histone Acetylation
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Epigenetics
Epigenetics
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Heterochromatin
Heterochromatin
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Gene Expression Regulation
Gene Expression Regulation
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RNA Polymerase
RNA Polymerase
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Nucleases
Nucleases
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Chromosome Organization
Chromosome Organization
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Chromatin Density
Chromatin Density
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Fluorescence in Situ Hybridization (FISH)
Fluorescence in Situ Hybridization (FISH)
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DNA Repeated Regions
DNA Repeated Regions
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Exclude Transcription Zones
Exclude Transcription Zones
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Nuclear Structure
Nuclear Structure
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Heterochromatin Locations
Heterochromatin Locations
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Gene Expression Control
Gene Expression Control
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Protection from Nucleases
Protection from Nucleases
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Chromosomal Rearrangement in Cancer
Chromosomal Rearrangement in Cancer
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H1 Histone Effect
H1 Histone Effect
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Transcription factors role
Transcription factors role
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Active vs Inactive Chromatin
Active vs Inactive Chromatin
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Condensation and Transcription
Condensation and Transcription
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Chromatin Regulation Mechanism
Chromatin Regulation Mechanism
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Transcription Active Configuration
Transcription Active Configuration
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Impact of Histone Binding
Impact of Histone Binding
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Gene Regulation in Development
Gene Regulation in Development
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Base Switching Mechanism
Base Switching Mechanism
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Nucleosome Formation
Nucleosome Formation
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Transcription Regulation Factors
Transcription Regulation Factors
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Early vs Late Gene Expression
Early vs Late Gene Expression
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DNA Accessibility
DNA Accessibility
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Histone Phosphorylation
Histone Phosphorylation
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Chain Reaction of Modifications
Chain Reaction of Modifications
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Serine Ten Modification
Serine Ten Modification
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Acetylation
Acetylation
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Methylation on DNA
Methylation on DNA
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DNA Methyltransferase
DNA Methyltransferase
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Histone Deacetylase
Histone Deacetylase
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Histone Modifications
Histone Modifications
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CPG Methylation
CPG Methylation
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Methyl Binding Proteins
Methyl Binding Proteins
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Histone Interaction Regulation
Histone Interaction Regulation
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Post-translational Modifications
Post-translational Modifications
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Histone Acetylation Inhibition
Histone Acetylation Inhibition
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Chromatin State Regulation
Chromatin State Regulation
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Phosphorylation Influence
Phosphorylation Influence
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Acetylation of Lysine
Acetylation of Lysine
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Heterochromatin to Euchromatin
Heterochromatin to Euchromatin
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Promoter Protein Recruitment
Promoter Protein Recruitment
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Histone Methylation
Histone Methylation
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Histone Methyltransferase
Histone Methyltransferase
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Histone Demethylation
Histone Demethylation
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Acetylation & Methylation Cooperation
Acetylation & Methylation Cooperation
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Phosphorylation of Histones
Phosphorylation of Histones
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Propagation of Methylation
Propagation of Methylation
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Promoter and Chromo Domain Proteins
Promoter and Chromo Domain Proteins
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Transcription Dynamics
Transcription Dynamics
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Positive & Negative Charges on Histones
Positive & Negative Charges on Histones
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Restriction Enzyme Assay
Restriction Enzyme Assay
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Nucleosome Binding
Nucleosome Binding
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Transcription Levels
Transcription Levels
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Hypothesis One
Hypothesis One
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Hypothesis Two
Hypothesis Two
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Result One
Result One
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Result Two
Result Two
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Transcription Repression
Transcription Repression
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H1 Histone Role
H1 Histone Role
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Observation One
Observation One
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Observation Two
Observation Two
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Repressed Chromatin
Repressed Chromatin
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RNA Product Formation
RNA Product Formation
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Histone Configuration
Histone Configuration
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Histone Tails
Histone Tails
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Phosphorylation
Phosphorylation
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Histone Acetyl Transferase
Histone Acetyl Transferase
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Effect of Acetylation
Effect of Acetylation
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Chromatin Structure
Chromatin Structure
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Histone Modification Reversibility
Histone Modification Reversibility
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Role of Lysine in Histones
Role of Lysine in Histones
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Methylation Events
Methylation Events
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Study Notes
DNA Structure and Chromatin Organization
- Human cells contain ~3.2 billion base pairs of DNA, split across 46 chromosomes (23 pairs).
- If stretched, this DNA would reach from Miami to Fairbanks, Alaska.
- Each chromosome pair: one copy from mother, one from father.
- All 46 chromosomes, when lined up, would be ~2 meters long, while the cell nucleus diameter is ~10 micrometers (20,000 times smaller).
Chromosome Packaging
- DNA packaging into a cell nucleus is crucial for fitting it inside, protection from damage and mutations, controlling gene expression.
- DNA wraps around histone proteins, forming nucleosomes (basic structural unit).
- Nucleosomes wind into a solenoid structure.
- Further coiling produces the higher order structures of chromosomes, evident during mitosis.
Chromatin vs. Chromosome
- Chromatin: DNA and associated proteins (mainly during interphase).
- Chromosome: Condensed DNA (present during mitosis only).
- Chromosome number: the total number of chromosomes per cell.
- Ploidy: The number of sets of chromosomes in a cell, e.g., diploid (2 sets), triploid (3 sets).
- Humans are diploid
Nucleosome Structure
- Nucleosomes consist of 8 histone proteins (2 each of H2A, H2B, H3, and H4).
- DNA wraps around these histone octamers ~1.76 times.
- Histones have unstructured N-terminal tails, important for interactions with other histones and DNA.
- Arginine residues (positively charged) are common in histones due to electrostatic interactions with negatively charged DNA.
Levels of DNA Organization
- Nucleosomes form a 10nm fibre.
- Nucleosomes form a 30nm fibre; the tails of the histones forming bridges between nucleosomes for this structure.
- This fibre can further coil and condense to form visible chromosomes.
- H1 histones acts like molecular glue to hold this together preventing the 30nm fibre from dispersing.
Techniques to Study DNA Packaging
- Nucleosome digestion assays: Use DNAse I to determine the length of DNA that wraps around the nucleosomes .
- This shows the spacing between nucleosomes.
- Analyzing digested sequences shows nucleosome positions and spacing.
Chromatin Regulation: Heterochromatin vs Euchromatin
- Heterochromatin: Densely packed chromatin, associated with less active gene expression. Often contains repeated sequences, telomeres, and centromeres.
- Euchromatin: Less densely packed chromatin, associated with active gene expression.
- Chromatin structure impacts transcription levels, as open or close compaction allows access to transcription factors and RNA polymerase.
Post-Translational Modifications of Histones
- Histone modifications (acetylation, methylation, phosphorylation) alter histone-DNA interactions and affect chromatin structure
- Histone modifications are often reversible; enzymes add/remove modifications.
- Acetylation: Loosens chromatin for transcription by removing positive charge.
- Methylation: Can either promote active or inactive chromatin, depending on the context.
- Phosphorylation: Adding negative charge can influence gene activation or silencing, depending on the context.
DNA Methylation
- DNA methylation (adding methyl groups to DNA bases) affects chromatin structure and gene expression.
- Methylation is associated with silencing gene expression
- Methylation is part of epigenetics.
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