Cell Division: Cytokinesis
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Questions and Answers

What is the function of the nuclear lamina in the cell?

  • Maintaining cell shape
  • Regulating movement of macro-molecules
  • Stabilizing the nuclear envelope (correct)
  • Controlling DNA replication
  • Which proteins bind to membrane proteins and associate with chromatin in nondividing cells?

  • Nucleoporins
  • Histones
  • Lamins (correct)
  • Cohesins
  • What is the primary function of nuclear pore complexes?

  • Regulating DNA replication
  • Promoting cell division
  • Facilitating molecular transfer (correct)
  • Maintaining cell shape
  • How is the transport of proteins across the nuclear envelope powered?

    <p>GTP hydrolysis</p> Signup and view all the answers

    Which proteins are associated with the compaction of chromatin within the nucleus?

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

    What is the main function of the nucleus in a cell?

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

    During interphase, what is the role of pore complexes in the nucleus?

    <p>Facilitating macromolecular transfer</p> Signup and view all the answers

    What is the function of nucleoli within the nucleus?

    <p>Producing RNA molecules</p> Signup and view all the answers

    Why does the nuclear envelope have a selective permeability?

    <p>To create a barrier between nuclear and cytoplasmic compartments</p> Signup and view all the answers

    What is the significance of the size and shape of nuclei in specific tissues being uniform?

    <p>Maintains cellular homeostasis</p> Signup and view all the answers

    Which type of chromatin is rich with genes and shows more transcriptional activity?

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

    What is the main characteristic of heterochromatin compared to euchromatin?

    <p>Contains mainly repetitive, gene-poor DNA sequences</p> Signup and view all the answers

    Where is constitutive heterochromatin usually located in the chromosome?

    <p>Near the centromere</p> Signup and view all the answers

    What is the main difference between constitutive and facultative heterochromatin?

    <p>Facultative can undergo reversible transitions</p> Signup and view all the answers

    What does the ratio of heterochromatin to euchromatin staining indicate about a cell's activity?

    <p>Metabolic and biosynthetic activity</p> Signup and view all the answers

    What is the function of the nucleolus in a cell?

    <p>Assembly of ribosomal subunits</p> Signup and view all the answers

    Why are cells of most tissues considered diploid?

    <p>As they have pairs of chromosomes, termed homologous</p> Signup and view all the answers

    What process is used to obtain chromosomes for karyotyping?

    <p>Staining cells and analyzing them under a light microscope</p> Signup and view all the answers

    What is the main reason for the intense basophilia of nucleoli?

    <p>Densely concentrated ribosomal RNA (rRNA)</p> Signup and view all the answers

    What can result from mutations in the gene coding for lamin A?

    <p>Onset of premature aging in progeria</p> Signup and view all the answers

    During which phase of the cell cycle does DNA replication occur?

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

    Which phase of the cell cycle is usually the longest and most variable?

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

    What triggers the cascade of kinase signaling in postmitotic G0 cells to activate cycling?

    <p>Mitogens or growth factors</p> Signup and view all the answers

    Which proteins are responsible for removing cyclins during the cell cycle?

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

    What halts progression through the cell cycle in response to adverse conditions such as DNA damage?

    <p>Tumor suppressor genes</p> Signup and view all the answers

    What type of genes can convert to oncogenes causing uncontrolled cell growth and cancer?

    <p>Proto-oncogenes</p> Signup and view all the answers

    Which gene is responsible for blocking cell cycle progression until a mitogenic stimulus arrives?

    <p>Rb gene</p> Signup and view all the answers

    During which phase of the cell cycle do the chromosomes condense into discrete threadlike structures?

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

    What structures move the chromosomes into alignment at the equatorial plate during mitosis?

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

    In anaphase of mitosis, what moves sister chromatids toward opposite spindle poles?

    <p>Mitotic spindle</p> Signup and view all the answers

    During cytokinesis, what structure is responsible for producing a cleavage furrow in the cell?

    <p>Contractile ring of actin filaments</p> Signup and view all the answers

    Which stage of the cell cycle is characterized by DNA replication?

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

    Where are stem cells typically found in tissues?

    <p>In specific locations or niches</p> Signup and view all the answers

    What characterizes meiosis as a specialized process?

    <p>Synapsis of homologous chromosomes</p> Signup and view all the answers

    Which type of tissue has stem cells that are not easily visible using routine histologic methods?

    <p>Connective tissues</p> Signup and view all the answers

    What is the result of synapsis during meiosis?

    <p>Crossover between homologous chromosomes</p> Signup and view all the answers

    Why are the cells produced after meiosis considered haploid?

    <p>They have just one chromosome from each pair</p> Signup and view all the answers

    What is the significance of synapsis recombination or crossing over during meiosis?

    <p>It mixes up the genes inherited from each parent</p> Signup and view all the answers

    How does meiosis differ from mitosis in terms of genetic uniqueness?

    <p>Meiosis involves crossing over to produce genetic uniqueness</p> Signup and view all the answers

    What happens during the second meiotic division?

    <p>Cohesin proteins are lost</p> Signup and view all the answers

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