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Eukaryotic Chromatin Modifications quiz #2 Flashcards

Eukaryotic Chromatin Modifications quiz #2
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  • What is chromatin?
    Chromatin is a complex of DNA and histone proteins that forms a structure in the nucleus of eukaryotic cells. It can be loosely packed (euchromatin) or tightly packed (heterochromatin), affecting gene expression.
  • What is the function of ATP-dependent chromatin-remodeling complexes?
    ATP-dependent chromatin-remodeling complexes use energy from ATP hydrolysis to alter chromatin structure, making DNA more or less accessible for transcription.
  • Histone modifications can result in which of the following: a) Increased transcription, b) Decreased transcription, c) No change in transcription, d) All of the above?
    d) All of the above. Histone modifications can increase, decrease, or have no effect on transcription depending on the type of modification and context.
  • DNA methylation and histone acetylation are examples of which of the following processes: a) Genetic mutations, b) Epigenetic modifications, c) DNA replication, d) Protein synthesis?
    b) Epigenetic modifications. These processes modify gene expression without altering the DNA sequence.
  • What is heterochromatin?
    Heterochromatin is a tightly packed form of chromatin that is transcriptionally inactive, preventing gene expression.
  • What does the DNA methylation mechanism used by eukaryotes do?
    DNA methylation adds methyl groups to cytosine residues, typically silencing genes by blocking transcription.
  • What is the difference between euchromatin and heterochromatin?
    Euchromatin is loosely packed and transcriptionally active, while heterochromatin is tightly packed and transcriptionally inactive.
  • What is euchromatin?
    Euchromatin is a loosely packed form of chromatin that is transcriptionally active, allowing gene expression.
  • Which of the following examples could potentially lead to epigenetic effects: a) Histone acetylation, b) DNA methylation, c) RNA interference, d) All of the above?
    d) All of the above. These processes can lead to changes in gene expression without altering the DNA sequence.
  • What is the difference between heterochromatin and euchromatin?
    Heterochromatin is tightly packed and transcriptionally inactive, while euchromatin is loosely packed and transcriptionally active.
  • Which of the following represent key functional roles for heterochromatin in eukaryotic cells: a) Gene silencing, b) Chromosome stability, c) Regulation of gene expression, d) All of the above?
    d) All of the above. Heterochromatin plays roles in gene silencing, maintaining chromosome stability, and regulating gene expression.
  • What occurs in histone acetylation and how does it affect gene expression?
    Histone acetylation involves adding acetyl groups to histone tails, loosening chromatin structure and enhancing gene expression by making DNA more accessible.
  • Which of the following are examples of heterochromatin: a) Centromeres, b) Telomeres, c) Inactive X chromosome, d) All of the above?
    d) All of the above. Centromeres, telomeres, and the inactive X chromosome are examples of heterochromatin.
  • Why are genes contained in compact chromatin not expressed?
    Genes in compact chromatin, or heterochromatin, are not expressed because the tightly packed structure prevents access by transcriptional machinery.
  • What effect can ATP-dependent chromatin remodeling have on transcription?
    ATP-dependent chromatin remodeling can either increase or decrease transcription by altering chromatin structure to make DNA more or less accessible.
  • Which statement is not true about eukaryotic chromosomes: a) They contain chromatin, b) They are always transcriptionally active, c) They can undergo modifications, d) They are found in the nucleus?
    b) They are always transcriptionally active. Eukaryotic chromosomes can be transcriptionally inactive when in heterochromatin form.
  • What effect does methylation of CpG islands have on human promoters?
    Methylation of CpG islands typically silences human promoters by preventing transcription factor binding and blocking transcription.
  • Of the proteins associated with chromatin, which are primarily involved in chromatin structure and gene regulation?
    Histone proteins are primarily involved in chromatin structure and gene regulation through modifications like acetylation and methylation.
  • What is the role of DNA methylation in eukaryotes?
    DNA methylation in eukaryotes typically silences genes by adding methyl groups to cytosine residues, blocking transcription.
  • How do histone acetylation and DNA methylation affect gene expression in eukaryotic cells?
    Histone acetylation loosens chromatin structure, forming euchromatin and increasing gene transcription by making DNA accessible to RNA polymerase. DNA methylation adds methyl groups to cytosine residues, leading to chromatin condensation (heterochromatin) and gene silencing by blocking RNA polymerase access.