Chromatin Structure and Function
10 Questions
5 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

What is the primary role of histone H1 in chromatin structure?

  • Binding to nucleosomes and linker DNA (correct)
  • Condensing DNA into chromosomes
  • Facilitating DNA replication
  • Promoting transcription of genes

    • Euchromatin is highly condensed and inaccessible to transcription.

    False (B)

    What type of DNA is found in mitochondria?

    Circular DNA

    DNA _____ can impact gene expression by binding to promoter regions.

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

    Match the type of chromatin with its characteristics:

    <p>Heterochromatin = Highly condensed and transcriptionally inactive Euchromatin = Less condensed and transcriptionally active Barr bodies = Inactivated X chromosomes DNA methylation = Gene expression regulation</p> Signup and view all the answers

    Which of the following processes typically leads to transcriptional repression?

    <p>Histone methylation (B), Histone deacetylation (C), DNA methylation (D)</p> Signup and view all the answers

    Removal of acetyl groups leads to relaxed DNA coiling and transcriptional activation.

    <p>False (B)</p> Signup and view all the answers

    Name a condition associated with dysregulation of DNA methylation.

    <p>Fragile X syndrome</p> Signup and view all the answers

    Histone methylation usually causes transcriptional _____ but can sometimes cause activation.

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

    What type of acids can lysine and arginine residues of histones be modified with?

    <p>Methyl groups (B)</p> Signup and view all the answers

    Flashcards

    Chromatin Structure

    DNA is tightly packed around histone proteins, forming nucleosomes. These nucleosomes further coil into a chromatin fiber. This structure allows the long DNA molecule to fit inside the nucleus.

    Heterochromatin

    A type of chromatin that is highly condensed and transcriptionally inactive. Genes in heterochromatin are typically "switched off."

    Euchromatin

    A type of chromatin that is less condensed and transcriptionally active. Genes in euchromatin are typically "switched on."

    DNA Methylation

    A chemical modification of DNA that can alter gene expression without changing the DNA sequence. It often silences genes.

    Signup and view all the flashcards

    Histone Methylation

    A modification of histone proteins that typically leads to gene repression. Methyl groups are added to specific amino acids on histones.

    Signup and view all the flashcards

    Histone Acetylation

    A modification of histone proteins that often leads to gene activation. Acetyl groups are added to histone tails, making the DNA more accessible.

    Signup and view all the flashcards

    Histone Deacetylation

    The removal of acetyl groups from histone tails. This typically results in tighter DNA coiling and gene repression.

    Signup and view all the flashcards

    CpG Islands

    Special regions of DNA that are commonly methylated. These regions are often located near gene promoters and are important for regulating gene expression.

    Signup and view all the flashcards

    Fragile X Syndrome

    A genetic condition that is often due to defects in DNA methylation. It can lead to intellectual disability and physical abnormalities.

    Signup and view all the flashcards

    Histone Acetylation

    The process of adding acetyl groups to histones, leading to looser DNA coiling and increased gene expression.

    Signup and view all the flashcards

    Study Notes

    Chromatin Structure

    • DNA exists in condensed chromatin form to fit in the nucleus.
    • DNA loops around histone octamers, forming nucleosomes.
    • Histone H1 binds to nucleosomes and linker DNA, stabilising the chromatin.
    • DNA has a negative charge from phosphate groups.
    • Histones have a positive charge from lysine and arginine.
    • In mitosis, DNA condenses to form chromosomes.
    • Mitochondrial DNA is circular and doesn't use histones.

    Heterochromatin

    • Appears darker on electron microscopy (EM).
    • Sterically inaccessible, thus transcriptionally inactive.
    • Often associated with methylation and acetylation.
    • Also called highly condensed chromatin.
    • May include inactive X chromosomes (Barr bodies).

    Euchromatin

    • Appears lighter on EM.
    • Transcriptionally active and sterically accessible.
    • True and "truly transcribed."

    DNA Methylation

    • Reverses changes to DNA segment expression without changing the sequence itself.
    • Involves aging, carcinogenesis, and epigenetics.
    • Genomic imprinting, transposable element repression, and X-chromosome inactivation can also be involved.

    Histone Methylation

    • Generally causes transcriptional suppression and may also cause activation depending on location of methylation.

    Histone Acetylation

    • Removal of histone's charge relaxes the DNA, which relaxes coiling and activates transcription.

    Histone Deacetylation

    • Removal of acetyl groups tightens DNA and inactivates transcription.

    Studying That Suits You

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

    Quiz Team

    Description

    This quiz explores the structure and types of chromatin, including heterochromatin and euchromatin. It delves into DNA methylation and its effects on gene expression. Understand the significance of chromatin in cellular processes and its impact on genetics.

    More Like This

    Use Quizgecko on...
    Browser
    Open
    Browser
    Browser