Cell Division: Cytokinesis

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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?

GTP hydrolysis Signup and view all the answers

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

Condensins Signup and view all the answers

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

Synthesizing proteins Signup and view all the answers

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

Facilitating macromolecular transfer Signup and view all the answers

What is the function of nucleoli within the nucleus?

Producing RNA molecules Signup and view all the answers

Why does the nuclear envelope have a selective permeability?

To create a barrier between nuclear and cytoplasmic compartments Signup and view all the answers

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

Maintains cellular homeostasis Signup and view all the answers

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

Euchromatin Signup and view all the answers

What is the main characteristic of heterochromatin compared to euchromatin?

Contains mainly repetitive, gene-poor DNA sequences Signup and view all the answers

Where is constitutive heterochromatin usually located in the chromosome?

Near the centromere Signup and view all the answers

What is the main difference between constitutive and facultative heterochromatin?

Facultative can undergo reversible transitions Signup and view all the answers

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

Metabolic and biosynthetic activity Signup and view all the answers

What is the function of the nucleolus in a cell?

Assembly of ribosomal subunits Signup and view all the answers

Why are cells of most tissues considered diploid?

As they have pairs of chromosomes, termed homologous Signup and view all the answers

What process is used to obtain chromosomes for karyotyping?

Staining cells and analyzing them under a light microscope Signup and view all the answers

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

Densely concentrated ribosomal RNA (rRNA) Signup and view all the answers

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

Onset of premature aging in progeria Signup and view all the answers

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

S Signup and view all the answers

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

G1 Signup and view all the answers

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

Mitogens or growth factors Signup and view all the answers

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

Proteasomes Signup and view all the answers

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

Tumor suppressor genes Signup and view all the answers

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

Proto-oncogenes Signup and view all the answers

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

Rb gene Signup and view all the answers

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

Prophase Signup and view all the answers

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

Kinetochores Signup and view all the answers

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

Mitotic spindle Signup and view all the answers

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

Contractile ring of actin filaments Signup and view all the answers

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

S phase Signup and view all the answers

Where are stem cells typically found in tissues?

In specific locations or niches Signup and view all the answers

What characterizes meiosis as a specialized process?

Synapsis of homologous chromosomes Signup and view all the answers

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

Connective tissues Signup and view all the answers

What is the result of synapsis during meiosis?

Crossover between homologous chromosomes Signup and view all the answers

Why are the cells produced after meiosis considered haploid?

They have just one chromosome from each pair Signup and view all the answers

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

It mixes up the genes inherited from each parent Signup and view all the answers

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

Meiosis involves crossing over to produce genetic uniqueness Signup and view all the answers

What happens during the second meiotic division?

Cohesin proteins are lost Signup and view all the answers