Genome and Chromosome Structure Quiz
18 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

What is the main characteristic of highly repetitive sequences in a genome?

  • They are involved in transposon mobility across the genome.
  • They consist of functional genes essential for survival.
  • They are single-copy sequences spread throughout the genome.
  • They contain multiple copies, such as satellite DNA. (correct)

In the structure of prokaryotic chromosomes, what role does DNA gyrase play?

  • It assists in the compaction of chromatin.
  • It introduces positive supercoiling in DNA.
  • It creates looped domains in bacterial DNA.
  • It induces negative supercoiling to aid replication and transcription. (correct)

Which of the following correctly distinguishes constitutive from facultative heterochromatin?

  • Constitutive heterochromatin is involved in gene expression, while facultative heterochromatin remains inactive.
  • Facultative heterochromatin is always compacted, while constitutive heterochromatin is transcriptionally active.
  • Facultative heterochromatin is permanently condensed, contrasting with the dynamic nature of constitutive heterochromatin.
  • Constitutive heterochromatin is found in centromeres, while facultative heterochromatin can change its locations within the genome. (correct)

What feature of eukaryotic chromosomes contributes to their compact structure?

<p>Beads-on-a-string structure formed by histones and DNA. (D)</p> Signup and view all the answers

Which process is primarily responsible for the compaction of DNA into looped domains in eukaryotic chromosomes?

<p>Binding of CTCF and SMC proteins to chromosome regions. (A)</p> Signup and view all the answers

During which stage of cell division is chromosomal compaction maximized?

<p>Metaphase at the highest level of compaction. (A)</p> Signup and view all the answers

What best describes the C-Value Paradox?

<p>It suggests that genome size does not correspond to the complexity of the organism. (A)</p> Signup and view all the answers

What type of chromatin is primarily responsible for transcriptional activity?

<p>Euchromatin. (D)</p> Signup and view all the answers

Which statement accurately describes the function of topoisomerases in DNA compaction?

<p>They aid in both positive and negative supercoiling processes. (C)</p> Signup and view all the answers

What distinguishes tandem repeats from other types of repetitive sequences?

<p>They are short sequences such as Alu elements. (A)</p> Signup and view all the answers

How does negative supercoiling benefit bacterial DNA during replication and transcription?

<p>It facilitates easier unwinding of the DNA strands. (B)</p> Signup and view all the answers

What primarily influences the transition between euchromatin and heterochromatin states?

<p>The action of specific histone modifying enzymes. (D)</p> Signup and view all the answers

Which of the following best describes the nature of constitutive heterochromatin?

<p>It is always condensed and located in centromeres. (B)</p> Signup and view all the answers

What role does the CTCF protein play in chromosome structure?

<p>It facilitates the creation of looped domains. (A)</p> Signup and view all the answers

What mechanism is involved in the relaxation of positive supercoiling in bacterial DNA?

<p>Action of Topoisomerase I. (B)</p> Signup and view all the answers

Which level of chromosomal structure is achieved after the formation of the 30 nm fiber?

<p>Looped domains (D)</p> Signup and view all the answers

What phenomenon describes the lack of correlation between genome size and organismal complexity?

<p>C-Value Paradox. (D)</p> Signup and view all the answers

What primarily characterizes moderately repetitive sequences in the genome?

<p>They have variable lengths and functions. (C)</p> Signup and view all the answers

Flashcards

Genome

The complete set of genetic material in an organism.

Transposable Element

A DNA sequence that can move within a genome.

C-Value Paradox

Genome size doesn't always correlate with organism complexity.

Chromosome

A threadlike structure of DNA and protein that carries genetic information.

Signup and view all the flashcards

Negative Supercoiling

DNA unwinding, aiding replication and transcription.

Signup and view all the flashcards

Nucleosome

DNA wrapped around histone proteins, creating a bead-like structure.

Signup and view all the flashcards

Heterochromatin

Densely packed, inactive chromatin.

Signup and view all the flashcards

Euchromatin

Less condensed chromatin, involved in active transcription.

Signup and view all the flashcards

Metaphase Chromosome

Highly condensed chromosome structure during cell division.

Signup and view all the flashcards

Repetitive Sequences

DNA sequences that occur multiple times in a genome. Can be highly repetitive, moderately repetitive, or tandem repeats.

Signup and view all the flashcards

Satellite DNA

Highly repetitive sequences often found at centromeres and telomeres.

Signup and view all the flashcards

rRNA Genes

Moderately repetitive sequences that code for ribosomal RNA, essential for protein synthesis.

Signup and view all the flashcards

Alu Elements

Short, tandem repeat sequences found in human DNA. Can be involved in disease development.

Signup and view all the flashcards

DNA Gyrase

A topoisomerase enzyme (Topoisomerase II) that introduces negative supercoiling in bacterial DNA. Helps with replication and transcription.

Signup and view all the flashcards

NAPs (Nucleoid-Associated Proteins)

Proteins that organize bacterial DNA into looped domains, contributing to chromosome compaction.

Signup and view all the flashcards

Histones

Proteins around which DNA is wrapped in eukaryotic cells, forming nucleosomes.

Signup and view all the flashcards

Constitutive Heterochromatin

Always condensed chromatin, often found at centromeres and telomeres. Genetically inactive.

Signup and view all the flashcards

Facultative Heterochromatin

Chromatin that can vary in its condensation depending on the cell type or developmental stage.

Signup and view all the flashcards

Study Notes

Genome Structure

  • Genome: The complete set of genetic material in an organism, composed of nucleotides.
  • Transposable Elements: DNA sequences that can move within the genome ("jumping genes").
  • C-Value Paradox: Genome size does not consistently correlate with organism complexity.
  • Repetitive Sequences: Varying copy numbers and functions within the genome
    • Highly Repetitive: Multiple copies of short sequences (satellite DNA).
    • Moderately Repetitive: Functional sequences, like rRNA genes, present in multiple copies.
    • Tandem Repeats: Short sequences repeated in succession (Alu elements).

Chromosome Structure and Compaction

Bacterial Chromosome

  • Compaction by supercoiling.
  • Negative Supercoiling: DNA is unwound (left-handed twist) by DNA gyrase (Topoisomerase II), essential for replication and transcription.
  • Positive Supercoiling: DNA is overwound (right-handed twist), relaxed by Topoisomerase I.
  • Looped Domains: Organized into microdomains and macrodomains by Nucleoid-associated proteins (NAPs).

Eukaryotic Chromosome

  • Chromatin: DNA-protein complex, packing material for DNA.
    • Euchromatin: Less condensed, active in transcription.
    • Heterochromatin: Highly condensed, inactive in transcription.
      • Constitutive Heterochromatin: Always condensed, found at centromeres.
      • Facultative Heterochromatin: Variable, location can change.

Chromosome Compaction Process

  • DNA Double Helix: The basic structure of DNA.

  • Nucleosome: DNA wrapped around histone proteins (like "beads on a string").

  • Zigzag/30 nm Fiber: Further compaction of nucleosomes.

  • Looped Domains: Formation of large loops involving CTCF and SMC proteins.

  • Heterochromatin: Further compaction of looped domains.

  • Metaphase Chromosome: The most compacted form of a chromosome, achieved during cell division.

Studying That Suits You

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

Quiz Team

Description

Test your knowledge on genome and chromosome structure, including the concepts of transposable elements, the C-value paradox, and DNA compaction techniques. This quiz covers mechanisms like supercoiling and the organization of bacterial chromosomes. Challenge yourself with this comprehensive overview of genetic material!

More Like This

Use Quizgecko on...
Browser
Open
Browser
Browser