Cell Biology: Nucleus and Chromatin Quiz
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Questions and Answers

What is the typical diameter range of the nucleus in human cells?

  • 9-10µm
  • 7-8µm (correct)
  • 5-6µm
  • 3-4µm

    • Which of the following adequately describes the shape of a nucleus?

  • Only oval or flattened
  • Always circular or spherical
  • Can be rounded, oval, flat, horse-shoe, kidney-shaped, segmented, or lobulated (correct)
  • Typically rectangular or triangular

    • In which state does the nucleus exhibit condensed chromatin and appear stained dark?

  • Active state with extensive nucleoli
  • Reactive state following cellular injury
  • Transitional state between active and inactive
  • Inactive state with tightly packed chromatin (correct)

    • What is the primary component of chromatin found within the nucleus?

    <p>A complex of DNA and proteins (histones)</p> Signup and view all the answers

    How many nuclei can a cell have according to the provided information?

    <p>One (mononucleated), two (binucleated), or multiple nuclei (multinucleated)</p> Signup and view all the answers

    What is the primary function of nuclear pores in the nuclear membrane?

    <p>To allow the passage of macromolecules</p> Signup and view all the answers

    Euchromatin can be described as which of the following?

    <p>Extended, pale in staining, carries active genes</p> Signup and view all the answers

    Which type of chromatin is typically associated with inactive genes and appears darker in staining?

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

    What is the structural composition of chromatin?

    <p>Nucleoprotein consisting of DNA and histone proteins</p> Signup and view all the answers

    What characterizes the nucleolus within the nucleus?

    <p>It serves as a site for ribosome formation</p> Signup and view all the answers

    What components primarily make up a single chromatid?

    <p>A single DNA molecule and histone proteins</p> Signup and view all the answers

    How are nucleosomes connected to each other within a chromatid?

    <p>Via linker DNA (H1)</p> Signup and view all the answers

    Which of the following statements accurately describes histones?

    <p>Histones are basic proteins that interact with DNA.</p> Signup and view all the answers

    What constitutes a histone octamer in the structure of a nucleosome?

    <p>Two copies each of H2A, H2B, H3, and H4</p> Signup and view all the answers

    Which of the following statements regarding the biochemical structure of chromosomes is incorrect?

    <p>Each chromatid contains two identical DNA molecules.</p> Signup and view all the answers

    What is the primary role of the nuclear sap in cellular processes?

    <p>To facilitate the transport of ribosomes from the nucleus to the cytoplasm</p> Signup and view all the answers

    Which statement accurately describes a function performed by the nucleus?

    <p>It controls vital processes, including protein formation</p> Signup and view all the answers

    Which types of RNA are synthesized within the nucleus and essential for protein synthesis?

    <p>Messenger RNA (mRNA), transfer RNA (tRNA), and ribosomal RNA (rRNA)</p> Signup and view all the answers

    How many nucleoli can protein-forming cells possess?

    <p>One or two nucleoli</p> Signup and view all the answers

    What does the presence of chromosomes in the nucleus indicate regarding cellular function?

    <p>They carry genetic information necessary for protein synthesis</p> Signup and view all the answers

    What essential structural feature distinguishes sister chromatids in a duplicated chromosome?

    <p>A single centromere</p> Signup and view all the answers

    During which phase of cell division do chromosomes become visible under a light microscope?

    <p>Mitosis and Meiosis</p> Signup and view all the answers

    Which component is primarily responsible for the condensation and coiling of chromosomes during cell division?

    <p>Chromatin proteins</p> Signup and view all the answers

    What is the primary role of chromosomes in genetic inheritance?

    <p>Carrying genetic information</p> Signup and view all the answers

    How does the structure of a human cell's chromosomes relate to its function in cell division?

    <p>Chromosomes condense and align at the metaphase plate.</p> Signup and view all the answers

    What primarily occurs during the S phase of the cell cycle?

    <p>DNA duplication and centriole duplication</p> Signup and view all the answers

    In which stage of the cell cycle is a cell most likely to remain for a prolonged period, particularly in specialized cells?

    <p>G1 phase</p> Signup and view all the answers

    What is the role of telomeres in chromosomes?

    <p>To protect chromosome ends from degradation</p> Signup and view all the answers

    Which of the following statements about kinetochores is accurate?

    <p>They attach spindle fibers during cell division.</p> Signup and view all the answers

    Which type of chromosome is represented by two identical chromatids connected at a centromere?

    <p>Double chromosome</p> Signup and view all the answers

    What is the primary function of the G2 phase in the cell cycle?

    <p>Final preparation for mitosis</p> Signup and view all the answers

    Which cells are described as being unable to divide independently and originate from stem cells?

    <p>Blood cells</p> Signup and view all the answers

    During which phase of mitosis does the nuclear envelope disappear?

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

    What is the duration of the G2 phase?

    <p>4 hours</p> Signup and view all the answers

    What significant process occurs to ensure the accuracy of DNA during the G2 phase?

    <p>DNA checkpoint mechanism</p> Signup and view all the answers

    What is the function of H1 histone in chromatin structure?

    <p>It stabilizes the linker DNA between nucleosomes.</p> Signup and view all the answers

    Which of the following components forms the basic unit of chromatin structure?

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

    How many times does DNA wrap around the histone core in a nucleosome?

    <p>1.65 times</p> Signup and view all the answers

    What role do non-histone proteins play in chromatin structure?

    <p>They help organize the 30 nm fibers.</p> Signup and view all the answers

    Which histone proteins make up the octamer core of a nucleosome?

    <p>Two H2A, two H2B, two H3, and two H4</p> Signup and view all the answers

    Which chromatin fiber structure results from further coiling and folding of the 10 nm fiber?

    <p>30 nm fiber</p> Signup and view all the answers

    What modifications to histone tails can influence gene expression?

    <p>Phosphorylation and acetylation</p> Signup and view all the answers

    What primarily determines whether genes are expressed or silenced in chromatin?

    <p>Post-translational modifications to histone tails.</p> Signup and view all the answers

    What occurs during prophase in meiosis?

    <p>The nuclear envelope and nucleoli disappear.</p> Signup and view all the answers

    What is the primary role of the kinetochore during meiosis?

    <p>It attaches to sister chromatids and interacts with spindle fibers.</p> Signup and view all the answers

    Which statement about daughter chromosomes is correct?

    <p>They move toward opposite poles after anaphase.</p> Signup and view all the answers

    What key process begins during telophase?

    <p>Reformation of the nuclear envelope.</p> Signup and view all the answers

    During which stage of meiosis do chromosomes become visible?

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

    What is the role of centrioles during meiosis?

    <p>They assist in the formation of the spindle apparatus.</p> Signup and view all the answers

    What occurs at the end of cytokinesis?

    <p>Two daughter cells are produced, each with 46 chromosomes.</p> Signup and view all the answers

    What is the genetic composition of each resulting cell after meiosis?

    <p>Each cell contains one chromatid from each chromosome pair.</p> Signup and view all the answers

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