Epigenetics Quiz on DNA Methylation
42 Questions
0 Views

Choose a study mode

Play Quiz
Study Flashcards
Spaced Repetition
Chat to lesson

Podcast

Play an AI-generated podcast conversation about this lesson

Questions and Answers

Which of the following epigenetic mechanisms involves the addition of a methyl group to DNA?

  • DNA Methylation (correct)
  • Chromatin Remodeling
  • Histone Modification
  • Non-coding RNA
  • Most CpG islands in normal human cells are typically methylated.

    False

    What is the universal methyl donor involved in DNA methylation?

    S adenosyl methionine

    A cluster of CpG residues often found near gene promoters is known as a __________.

    <p>CpG island</p> Signup and view all the answers

    Match the following terms with their correct descriptions:

    <p>Nucleosomes = Basic repeating unit of chromatin Epigenetic Code = Mechanisms regulating gene expression without altering DNA sequence CpG Islands = Clusters of CpG residues near gene promoters Histone Modification = Change of histone proteins that impacts DNA accessibility</p> Signup and view all the answers

    Which modification enhances transcription by reducing the positive charges on histones?

    <p>Acetylation</p> Signup and view all the answers

    Histone deacetylation enhances transcription.

    <p>False</p> Signup and view all the answers

    What is the effect of methylation on histones?

    <p>It can form mono-methyl, di-methyl, or tri-methyl modifications, which play roles in gene regulation.</p> Signup and view all the answers

    H3K27me3 is primarily methylated by the methyltransferase called ______.

    <p>EZH2</p> Signup and view all the answers

    Match the following histone modifications with their primary effects:

    <p>Acetylation = Enhances transcription Deacetylation = Represses transcription Methylation of Arginine = Forms mono-, di-, and tri-methyl forms Methylation of Lysine = Varies between mono-, di-, and tri-methyl modifications</p> Signup and view all the answers

    What is one of the three known mechanisms of epigenetics?

    <p>DNA Methylation</p> Signup and view all the answers

    Increased cytosine methylation of the NR3C1 promoter is associated with suicide victims who had no childhood abuse.

    <p>False</p> Signup and view all the answers

    What role does the hypothalamic-pituitary-adrenal (HPA) axis play in relation to childhood abuse?

    <p>It alters stress responses and increases the risk of suicide.</p> Signup and view all the answers

    Core histones are rich in basic amino acids and have a structure consisting of three α helices connected by two ______.

    <p>loops</p> Signup and view all the answers

    Which histone modification is associated with gene activation?

    <p>Acetylation</p> Signup and view all the answers

    Match the following histone modifications with their functions:

    <p>Methylation = Gene silencing Acetylation = Gene activation Ubiquitination = Degradation tagging Sumoylation = Not for degradation tagging</p> Signup and view all the answers

    What are the possible effects of childhood abuse on NR3C1 mRNA levels?

    <p>Decrease in NR3C1 mRNA levels.</p> Signup and view all the answers

    Histone code refers to the specific modifications of histones that can dictate gene expression.

    <p>True</p> Signup and view all the answers

    What is the main focus of epigenetics?

    <p>Mechanisms beyond DNA sequence that affect gene expression</p> Signup and view all the answers

    Epigenetics can explain why identical twins may have different physical traits despite having the same DNA.

    <p>True</p> Signup and view all the answers

    Who first coined the term 'epigenetics'?

    <p>C.H. Waddington</p> Signup and view all the answers

    The process by which one parental allele is silenced is known as __________.

    <p>imprinting</p> Signup and view all the answers

    Match the following epigenetic concepts with their definitions:

    <p>Imprinting = Silencing of one parental allele X-inactivation = Dosage compensation in female mammals Stem cells = Cells that differentiate into specific cell types Epigenome = The genome with epigenetic modifications</p> Signup and view all the answers

    What is the length of each base pair in DNA?

    <p>0.34 nm</p> Signup and view all the answers

    All genes in a genome are expressed equally in every cell type.

    <p>False</p> Signup and view all the answers

    What phenomenon can lead to two different eye colors in a single individual?

    <p>Mosaicism</p> Signup and view all the answers

    What is the primary role of the PRC2 complex?

    <p>Transcriptional Repression</p> Signup and view all the answers

    H3K27me3 is associated with active gene promoters.

    <p>False</p> Signup and view all the answers

    What modification is known for shutting down transcription?

    <p>H3K27 trimethylation</p> Signup and view all the answers

    The enzyme __________ is part of the PRC2 complex that is involved in histone methylation.

    <p>EZH2</p> Signup and view all the answers

    Match the following chromatin modifications with their biological roles:

    <p>Methylated cytosine (meC) = Transcriptional Repression Acetylated lysine (Kac) = Transcriptional Activation Phosphorylated serine/threonine (S/Tph) = Transcriptional Activation Sumoylated lysine (Ksu) = Transcriptional Repression</p> Signup and view all the answers

    Which of the following lysine modifications is associated with transcriptional repression?

    <p>Methylated lysine (Kme)</p> Signup and view all the answers

    Acetylation and phosphorylation are associated with opening chromatin.

    <p>True</p> Signup and view all the answers

    What is the effect of H3K27 trimethylation on developmental genes?

    <p>It represses them.</p> Signup and view all the answers

    Which of the following best describes the role of long non-coding RNAs (lncRNAs) in DNA methylation regulation?

    <p>They can recruit DNMTs, sequester them, and influence their degradation.</p> Signup and view all the answers

    Histone acetyltransferases (HATs) are responsible for removing acetyl groups from histones.

    <p>False</p> Signup and view all the answers

    What is the hallmark of the epithelial-mesenchymal transition (EMT) process?

    <p>Loss of E-cadherin</p> Signup and view all the answers

    The interaction of Xist RNA with the X chromosome results in ______.

    <p>silencing</p> Signup and view all the answers

    Match the following enzymes or complexes to their functions:

    <p>DNMTs = DNA methylation HATs = Histone acetylation HDACs = Histone deacetylation EZH2 = Lysine methyltransferase</p> Signup and view all the answers

    What effect do acetylated lysine residues have on histones?

    <p>They promote transcriptional activation.</p> Signup and view all the answers

    Random X-inactivation in calico cats is based on genetic inheritance.

    <p>False</p> Signup and view all the answers

    What role does the Polycomb Repressive Complex 2 (PRC2) play in gene regulation?

    <p>Gene silencing</p> Signup and view all the answers

    Study Notes

    Epigenetics Introduction

    • Epigenetics is the study of heritable changes in gene expression or the phenotype.
    • These changes occur without alterations to the underlying DNA sequence.
    • Epigenetic changes are influenced by factors beyond DNA sequence, such as environment.
    • The term "Epi" means on top of/above.
    • Epigenetics was first coined by C.H. Waddington.
    • He used it to explain cell differentiation beyond genetics.
    • Waddington's work included genetic assimilation.
    • This involved the acquisition of inherited characteristics through environmental influences.
    • An example of Waddington's work was the crossveinless trait in Drosophila.
    • Different adult stem cells have specific fates.
    • Myoblasts form muscle and keratinocytes form skin cells.
    • Identical twins can have different hair and eye colors due to epigenetic changes.
    • Identical twin littermates can have different coat colors because of epigenetic changes.
    • Imprinting can silence one parental allele.
    • X-inactivation is a type of dosage compensation.

    Packing DNA into Chromatin

    • Each base pair in DNA is 0.34 nm long.
    • The human body has billions of base pairs per cell.
    • A typical cell has 2 meters of DNA, yet the nucleus measures only 2-10 μm.
    • Humans have approximately 50 trillion cells.
    • The DNA in a human body is 100 trillion meters long.
    • The distance between the Sun and Earth is 150 billion meters.
    • Each person's DNA could stretch from Earth to the Sun and back over 300 times.
    • Chromatin compacts DNA within the nucleus.

    Nucleosomes

    • The nucleosome is the fundamental unit of chromatin.
    • It is composed of histone octamer and 147 base pairs of DNA.
    • Histone proteins include H2A, H2B, H3, H4 (core histones) and H1 (linker histone).
    • It compacts DNA structure within the nucleus.
    • It associates with transcription.

    Mechanisms of Epigenetics

    • There are three main mechanisms of epigenetics:
      1. DNA methylation
      1. Histone modification
      1. Non-coding RNA

    DNA Methylation and Histone Modifications

    • DNA methylation involves methyl groups attached to specific DNA bases.
    • This often silences gene activity.
    • Histone modifications include various molecules attaching to histone tails.
    • These modifications alter the activity of the DNA around histones.

    Cytosine Methylation

    • Cytosine methylation involves adding a methyl group to cytosine bases in DNA.
    • Methylation commonly occurs at CpG sites.
    • The universal methyl donor is S-adenosylmethionine (SAM).

    CpG Islands

    • CpG islands are clusters of CpG sites often found near gene promoters.
    • A CpG island should have at least 200 base pairs and over a 60% GC content.
    • They are important for gene regulation.
    • Most CpG islands are unmethylated in normal cells.
    • They play a role in many processes, including cancer.

    Methylation Patterns in Diseases (e.g., Cancer)

    • Abnormal methylation patterns are associated with diseases like cancer.
    • This includes both global hypomethylation and focal hypermethylation of genes.
    • Dysregulation of tumor suppressor genes (TSGs) and oncogenes can be affected.

    Progressive Alterations in DNA Methylation in Cancer

    • Cancer development is associated with gradual changes in DNA methylation.
    • This encompasses shifts from global hypomethylation to regional hypermethylation.
    • This process involves an accumulation of epigenetic abnormalities.

    CpG Island Methylation

    • CpG island methylation is a stable, heritable, and detectable epigenetic signal that has important roles in normal development and disease.
    • CpG methylation patterns are readily observed and change in step and through the progression in disease.

    DNA Methylation in Stem Cells

    • DNA methylation differentiates totipotent embryonic stem cells from unipotent adult stem cells. The methylation patterns are different and distinguishable.

    How Methylation Inhibits Transcription

    • Methylation may inhibit the binding of regulatory factors to the DNA promoter region.
    • Methylation can prevent the binding of activator proteins to enhancer elements.
    • Methylation can cause proteins called methyl-CpG-binding proteins (MBPs) to bind.
    • These proteins recruit other proteins that then rearrange the chromatin to a less accessible conformation (often repressed).

    Establishment and Maintenance of Cytosine Methylation

    • De novo methylation occurs via DNMT3a and DNMT3b enzymes.
    • Maintenance methylation is aided by DNMT1.
    • These enzymes are vital for the regulation of epigenetic modifications.

    Bisulfite Sequencing

    • Bisulfite treatment is a DNA sequencing method for detecting methylation patterns.
    • The treatment will convert cytosine to uracil.
    • 5-methylcytosine nucleotides are unaffected.

    IncRNA and Epigenetics

    • Non-coding RNAs, including IncRNAs, influence epigenetics.
    • IncRNAs are associated with DNA methylation and histone modifications, and thereby regulate transcription.
    • IncRNAs can either activate or repress transcription.

    Chromatin Structure

    • Euchromatin: Active genes, accessible DNA, light-staining, open conformation.
    • Heterochromatin: Silent genes, inaccessible DNA, dark-staining, closed conformation.

    Core Histones

    • Core histone proteins (H2A, H2B, H3, H4) are highly conserved and enriched in basic amino acids.
    • These are important for DNA packaging.

    Histone Modifications

    • Histone modifications (methylation, acetylation, phosphorylation, ubiquitination, sumoylation, and other modifications) regulate gene expression.

    Methylation of Histone H3-K27

    • H3K27 methylation is associated with gene silencing
    • The enzyme EZH2 and Polycomb Repressive complexes (PRCs) mediate this methylation.

    Chromatin Modifications

    • Various modifications are associated with specific biological processes.
    • These include methylation of cytosine (DNA), acetylation or phosphorylation of lysines (histones), and methylation of arginines (histones).

    Maternal Behavior and Epigenetics

    • Maternal behaviors affect methylation patterns in offspring's brains.
    • Attentive or inattentive mothering can affect epigenetic modifications in offspring brains.

    Rainbow and Copycat Cats

    • Random X chromosome inactivation patterns result in distinctive coat patterns.
    • Coat coloring in calico cats due to stochastic inactivation.

    Xist RNA and Epigenetics

    • Xist IncRNA functions in cis to silence the X chromosome.
    • Xist interacts with transcriptional regulators via the chromatin.

    Histone Modifications and Modifiers

    • Histone modifiers include:
    • Writers (acetylases, methylases, phosphorylases)
    • Readers (proteins binding to the marks)
    • Erasers (deacetylases, demethylases, phosphatases)

    Studying That Suits You

    Use AI to generate personalized quizzes and flashcards to suit your learning preferences.

    Quiz Team

    Related Documents

    Description

    Test your knowledge of epigenetic mechanisms, particularly DNA methylation. This quiz covers key concepts such as CpG islands, histone modifications, and the roles of various methyltransferases. Dive deep into the effects of methylation and its implications on gene expression and behavior.

    More Like This

    Epigenetics and DNA Methylation Quiz
    10 questions
    Epigenetics: Concepts and Mechanisms
    12 questions
    Heritability and DNA Methylation
    54 questions
    Epigenetics Overview and Processes
    30 questions

    Epigenetics Overview and Processes

    EloquentMachuPicchu2662 avatar
    EloquentMachuPicchu2662
    Use Quizgecko on...
    Browser
    Browser