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

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

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

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

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

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

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

What is the function of nucleoli within the nucleus?

<p>Producing RNA molecules (C)</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 (B)</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 (C)</p> Signup and view all the answers

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

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

Where is constitutive heterochromatin usually located in the chromosome?

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

What is the main difference between constitutive and facultative heterochromatin?

<p>Facultative can undergo reversible transitions (B)</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 (D)</p> Signup and view all the answers

What is the function of the nucleolus in a cell?

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

Why are cells of most tissues considered diploid?

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

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

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

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

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

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

<p>G1 (B)</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 (A)</p> Signup and view all the answers

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

<p>Proteasomes (A)</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 (C)</p> Signup and view all the answers

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

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

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

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

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

<p>Prophase (C)</p> Signup and view all the answers

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

<p>Kinetochores (A)</p> Signup and view all the answers

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

<p>Mitotic spindle (D)</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 (B)</p> Signup and view all the answers

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

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

Where are stem cells typically found in tissues?

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

What characterizes meiosis as a specialized process?

<p>Synapsis of homologous chromosomes (A)</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 (C)</p> Signup and view all the answers

What is the result of synapsis during meiosis?

<p>Crossover between homologous chromosomes (B)</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 (A)</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 (A)</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 (A)</p> Signup and view all the answers

What happens during the second meiotic division?

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

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