Epigenetic Regulation Quiz
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Questions and Answers

What is the primary function of alternative splicing in gene expression?

  • Decreasing the stability of mRNA across all tissues
  • Producing different mature mRNA and subsequent proteins (correct)
  • Regulating the binding of RNA polymerase to DNA
  • Enhancing the transcription rate of genes

    • How does alternative polyadenylation affect mRNA?

  • It can suppress translation and affect mRNA stability (correct)
  • It exclusively enhances gene expression in all cases
  • It leads to the production of identical mRNA molecules
  • It only increases the size of mRNA transcripts

    • Which element is specifically involved in transcriptional activation in eukaryotes?

  • Upstream activation sequence (UAS) (correct)
  • Introns only
  • Repressor proteins
  • Spliceosome components

    • What is a consequence of using different poly(A) sites in pre-mRNA?

    <p>Regulation of oncogene expression and mRNA diversity</p> Signup and view all the answers

    What does the C-terminal domain (CTD) of RNA Polymerase II primarily regulate?

    <p>Transcriptional activation and RNA processing</p> Signup and view all the answers

    What is a primary role of histones in chromatin structure?

    <p>They serve as general repressors of transcription.</p> Signup and view all the answers

    Which histone modification is associated with gene activation?

    <p>Histone acetylation of H3 and H4.</p> Signup and view all the answers

    How does DNA methylation generally affect gene expression?

    <p>It generally renders DNA transcriptionally inactive.</p> Signup and view all the answers

    What are HATs responsible for in the context of histone modification?

    <p>Adding acetyl groups to histones.</p> Signup and view all the answers

    What is the consequence of methylation at CpG islands?

    <p>Transcriptional repression.</p> Signup and view all the answers

    Which histone modification typically indicates gene silencing?

    <p>Histone deacetylation of H3 and H4.</p> Signup and view all the answers

    Which statement about histone modifications is correct?

    <p>The histone code reflects specific modifications affecting gene expression.</p> Signup and view all the answers

    What type of chromatin is typically associated with high levels of DNA methylation?

    <p>Heterochromatin.</p> Signup and view all the answers

    What is the primary function of long non-coding RNA (lncRNA)?

    <p>Modulate chromatin function and alter mRNA stability</p> Signup and view all the answers

    Which of the following statements about RISC (RNA-induced silencing complex) is true?

    <p>RISC targets viral RNA for degradation.</p> Signup and view all the answers

    What mechanism primarily determines the stability of a protein?

    <p>mRNA lifespan</p> Signup and view all the answers

    Which of the following accurately describes the result of protein phosphorylation?

    <p>Activation of proteins</p> Signup and view all the answers

    Which of the following best describes the origin of RNAi?

    <p>It is a natural defense mechanism initially identified in plants.</p> Signup and view all the answers

    What is the primary function of Cyclin D1 in the context of the cell cycle?

    <p>Regulates the progression of the cell cycle</p> Signup and view all the answers

    Which of the following factors does NOT influence mRNA turnover?

    <p>The length of the mRNA transcript</p> Signup and view all the answers

    What is the mechanism by which RNA interference regulates gene expression?

    <p>Through small RNA molecules that induce gene silencing</p> Signup and view all the answers

    Which type of decay pathway does NOT rely on poly(A) degradation?

    <p>De-adenylation independent decay</p> Signup and view all the answers

    Which of the following best describes the stability time span of mRNA?

    <p>Varies significantly from minutes to days</p> Signup and view all the answers

    What role does methyltransferase enzyme play in DNA replication?

    <p>It makes the new strand of DNA methylated.</p> Signup and view all the answers

    What effect does cigarette smoke have on epigenetic changes?

    <p>It can cause global epigenetic changes in multiple tissues.</p> Signup and view all the answers

    What is genomic imprinting primarily responsible for?

    <p>Differential expression of maternal and paternal genes.</p> Signup and view all the answers

    How does folate deficiency during development affect health?

    <p>It increases the risk for neural tube defects.</p> Signup and view all the answers

    In Prader-Willi Syndrome, what is expressed when there is a deletion in the paternal chromosome?

    <p>Only maternal genes.</p> Signup and view all the answers

    What is a common symptom observed in Angelman Syndrome?

    <p>Large mandible.</p> Signup and view all the answers

    Which of the following is NOT a feature of Prader-Willi Syndrome?

    <p>Hypotonia.</p> Signup and view all the answers

    What is the key process that links maternal behavior to transgenerational effects in epigenetics?

    <p>Methylation changes.</p> Signup and view all the answers

    What typically induces gene silencing in genomic imprinting?

    <p>DNA methylation.</p> Signup and view all the answers

    Which of the following effects can result from early life experiences on behavior?

    <p>Long-lasting effects on behavior.</p> Signup and view all the answers

    Study Notes

    Epigenetic Regulation

    • Changes in chromatin structure and DNA methylation significantly affect gene expression.
    • Chemical modifications of histone proteins (e.g., methylation, acetylation) alter transcriptional activity.
    • RNA molecules play a role in modifying chromatin structure and influencing gene expression.

    Chromatin and Histone Modifications

    • Histones repress transcription generally; modifications can reverse this effect.
    • Key modifications include:
      • Histone methylation (activating marks: H3: K4, K36, K79; silencing marks: H3: K27, K9; H4: K20).
      • Histone acetylation typically stimulates transcription, while deacetylation reduces it.
      • Histone phosphorylation (notably at H3S10) and ubiquitylation impact gene regulation.
    • Methylated DNA, particularly within CpG islands, is often transcriptionally inactive.

    Maintenance of DNA Methylation

    • Methylation patterns are preserved through DNA replication.
    • Methyltransferase enzymes ensure methylation is passed to daughter strands.
    • Methylcytosines attract repressor proteins, contributing to gene silencing.

    Environmental Effects on Epigenetics

    • Behavioral epigenetics highlights how early life experiences can have lasting effects on behavior.
    • Nutritional deficiencies and environmental exposures, like folate deficiency and cigarette smoke, can induce epigenetic changes linked to health risks.

    Genomic Imprinting

    • Imprinting results in differential expression of maternal and paternal alleles for dosage compensation.
    • Key to the development of certain diseases and conditions, including Prader-Willi and Angelman syndromes.
    • The Prader-Willi Syndrome is characterized by paternal chromosome mutations leading to only maternal genes expressing, while Angelman Syndrome arises from mutations in the maternal allele.

    RNA Processing and Expression Control

    • Alternative splicing allows different intron-exon configurations leading to various proteins from the same gene.
    • Alternative polyadenylation affects mRNA stability and translation efficiency, increasing diversity in gene expression.
    • RNA stability is regulated by degradation control, with cis-elements residing in the 3’-UTR influencing mRNA turnover.

    RNA Interference (RNAi)

    • RNAi is a post-transcriptional regulation mechanism involving small RNA molecules like siRNAs and miRNAs.
    • It regulates gene expression through mRNA cleavage, translation inhibition, transcriptional silencing, and mRNA degradation.
    • RNAi mechanisms were initially discovered as a defense against viruses.

    Long Non-coding RNA (lncRNA)

    • lncRNAs are transcribed from DNA but are not translated into proteins. They play various regulatory roles in chromatin function and mRNA stability.
    • Functions of lncRNAs include modulation of chromatin states, interference in signaling pathways, and alteration of mRNA translation.

    Translational and Protein Control

    • Protein production is influenced by mRNA stability and degradation rates.
    • Phosphorylation typically activates proteins, while dephosphorylation leads to inactivation.
    • Factors like ubiquitin assist in protein degradation, affecting overall protein levels within the cell.

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    Description

    Test your understanding of epigenetic regulation, including changes in chromatin structure, DNA methylation patterns, and histone modifications. Explore how these molecular mechanisms influence gene expression and chromosome changes.

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