Podcast
Questions and Answers
What role does DNA methylation play in gene expression?
What role does DNA methylation play in gene expression?
Which of the following is NOT an epigenetic mechanism that influences gene expression?
Which of the following is NOT an epigenetic mechanism that influences gene expression?
How do microRNAs influence gene expression?
How do microRNAs influence gene expression?
What effect does chromatin remodeling have on gene expression?
What effect does chromatin remodeling have on gene expression?
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What is a primary function of epigenetic changes?
What is a primary function of epigenetic changes?
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Which of the following processes does NOT represent a way to modify protein expression after translation?
Which of the following processes does NOT represent a way to modify protein expression after translation?
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What role do post-translational modifications (PTMs) play in cellular function?
What role do post-translational modifications (PTMs) play in cellular function?
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What is the primary mechanism through which the epigenome influences gene expression?
What is the primary mechanism through which the epigenome influences gene expression?
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Which of the following is a major epigenetic regulator?
Which of the following is a major epigenetic regulator?
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How many genes are estimated to be present in the human genome?
How many genes are estimated to be present in the human genome?
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Single genes in the human genome can encode multiple proteins through which of the following mechanisms?
Single genes in the human genome can encode multiple proteins through which of the following mechanisms?
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What is the significance of cytosine phosphate-guanine (CpG) DNA methylation?
What is the significance of cytosine phosphate-guanine (CpG) DNA methylation?
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Which of the following is NOT a function of post-translational modifications?
Which of the following is NOT a function of post-translational modifications?
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What is the primary chemical change involved in DNA methylation?
What is the primary chemical change involved in DNA methylation?
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What region of the genome is typically associated with high levels of DNA methylation?
What region of the genome is typically associated with high levels of DNA methylation?
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Which enzyme is primarily responsible for adding methyl groups to cytosine bases?
Which enzyme is primarily responsible for adding methyl groups to cytosine bases?
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What role does S-adenosylmethionine (SAM) play in DNA methylation?
What role does S-adenosylmethionine (SAM) play in DNA methylation?
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How does DNA methylation typically affect gene expression?
How does DNA methylation typically affect gene expression?
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What is the function of maintenance methyltransferase after DNA replication?
What is the function of maintenance methyltransferase after DNA replication?
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What effect does histone methylation have on DNA?
What effect does histone methylation have on DNA?
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How does acetylation impact eukaryotic proteins?
How does acetylation impact eukaryotic proteins?
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What complex do mature miRNAs form with proteins to regulate gene expression?
What complex do mature miRNAs form with proteins to regulate gene expression?
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How does extensive complementarity between miRNA and target mRNA affect the target mRNA?
How does extensive complementarity between miRNA and target mRNA affect the target mRNA?
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What role does DNA methylation play in gene expression?
What role does DNA methylation play in gene expression?
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What is generally associated with a global loss of methylation?
What is generally associated with a global loss of methylation?
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What could influence DNA methylation patterns according to epigenetic studies?
What could influence DNA methylation patterns according to epigenetic studies?
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What technology is NOT commonly used to assess global measures of methylation?
What technology is NOT commonly used to assess global measures of methylation?
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Which developmental conditions have been associated with gains in global methylation levels?
Which developmental conditions have been associated with gains in global methylation levels?
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What is the primary function of the enzyme DNMT in relation to DNA methylation?
What is the primary function of the enzyme DNMT in relation to DNA methylation?
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Which of the following health outcomes are associated with arsenic exposure?
Which of the following health outcomes are associated with arsenic exposure?
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How does BPA exposure affect DNA methylation in women and young girls?
How does BPA exposure affect DNA methylation in women and young girls?
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What is a potential impact of tobacco smoke exposure on the epigenome?
What is a potential impact of tobacco smoke exposure on the epigenome?
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Which genes are affected by BPA exposure, particularly in relation to methylation?
Which genes are affected by BPA exposure, particularly in relation to methylation?
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Which type of changes in DNA methylation does fetal exposure to BPA induce?
Which type of changes in DNA methylation does fetal exposure to BPA induce?
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What is the effect of tobacco smoke on DNA methylation patterns over time?
What is the effect of tobacco smoke on DNA methylation patterns over time?
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Which statement is true regarding sex differences in arsenic's effect on DNA methylation?
Which statement is true regarding sex differences in arsenic's effect on DNA methylation?
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What kind of methylation alterations are commonly observed with arsenic exposure?
What kind of methylation alterations are commonly observed with arsenic exposure?
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Study Notes
Epigenetics Overview
- Epigenetics regulates gene expression by modifying protein expression levels without altering the DNA sequence.
- Epigenetic modifications allow organisms to rapidly adapt to environmental changes.
- The three main epigenetic regulators are:
- Histone modifications
- DNA methylation
- Noncoding RNA expression
Post-Translational Modifications
- Post-translational modifications alter proteins after translation.
- These modifications include:
- Methylation
- Acetylation
- Phosphorylation
- Glycosylation
- These modifications influence protein folding, stability, location in the cell, function, activation, and interactions with other molecules.
- Post-translational modifications significantly increase the diversity of the proteome, which is the complete set of proteins produced by an organism.
Epigenetic Mechanisms
- DNA methylation involves adding a methyl group (CH3) to cytosine bases in CpG dinucleotides.
- This modification usually inhibits transcription factors from binding to promoters.
- DNA methylation patterns are passed on to daughter cells during DNA replication.
- Chromatin remodeling (including histone methylation and acetylation) affects the structure of chromatin.
- This structure influences the accessibility of DNA for transcription.
- MicroRNAs (miRNAs) are small non-coding RNA molecules that regulate gene expression post-transcriptionally.
- They regulate gene expression by targeting specific messenger RNAs (mRNAs).
DNA Methylation
- DNA Methylation is the addition of a methyl group to the fifth carbon position of a cytosine base.
- Methylated cytosine (5-mC) bases are often located near guanine-5 CpG methylation.
- CpG methylation occurs in regions of the genome with high cytosine-guanine (CG) content. These regions are called CpG islands.
- The DNA methyltransferase (DNMT) enzyme family adds methyl groups to cytosine bases.
- The process requires the cofactor S-adenosylmethionine (SAM).
Chromatin Remodeling: Histone Methylation
- Histone methylation influences the accessibility of DNA for transcription.
- Histone methylation can involve adding one or multiple methyl groups to amino acid residues.
Acetylation
- Acetylation is the transfer of an acetyl group to nitrogen.
- It occurs in almost all eukaryotic proteins through both irreversible and reversible mechanisms.
MicroRNAs
- Mature miRNAs assemble with proteins to form a complex called RISC.
- RISC searches for mRNAs with complementary nucleotide sequences to the bound miRNA.
- Depending on the extent of the complementarity, the target mRNA is either degraded or transferred to an area of the cytoplasm where it is destroyed.
- miRNAs are important epigenetic regulators of gene and protein expression.
- They play a role in developmental processes and are influenced by environmental chemicals.
Epigenetics and the Environment
- Environmental factors can influence epigenetic modifications.
- Large-scale changes in methylation processes, due to environmental exposure, nutritional status, or disease, can cause global losses or gains of methylation.
- Global loss of methylation is associated with genomic instability, aging, and cancer.
- Global gains in methylation, particularly in the placenta, have been associated with developmental defects, including Down syndrome and gestational diabetes.
Current Research
- Arsenic Exposure:
- Arsenic exposure is linked to altered methylation patterns in adults and infants, resulting in hypomethylation and hypermethylation.
- Arsenic's effects on DNA methylation may vary by sex.
- Arsenic exposure is associated with gene-specific methylation changes, often resulting in hypermethylation.
- Bisphenol-A (BPA) Exposure:
- BPA induces hypomethylation in women and young girls.
- Fetal BPA exposure is associated with non-monotonic changes in DNA methylation in the liver.
- BPA alters methylation patterns in the placenta, fetal liver, and fetal kidney.
- Tobacco Smoke Exposure:
- Tobacco smoke exposure is associated with genomic instability and epigenetic dysregulation.
- Both in utero and adult exposure to tobacco smoke have been linked to global hypomethylation.
- Tobacco smoke exposure impacts genes related to cancer, cell cycle, metabolism, and fetal growth.
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Description
This quiz covers the fundamentals of epigenetics and post-translational modifications, exploring how these processes regulate gene expression and protein functionality. Participants will learn about key mechanisms such as DNA methylation, histone modifications, and various forms of post-translational modifications. Test your understanding of these essential biological processes.
