Cell Division II: M phase and Meiosis - BIOL 210/212

A comprehensive set of flashcards to enhance understanding and review key concepts related to the M phase of the cell cycle and meiosis, as presented in the BIOL 210/212 lecture.

What phases are included in the M phase of the cell cycle?

Metaphase, Anaphase, Telophase, Cytokinesis.

What is the key difference in chromosomal behavior between meiosis and mitosis?

Meiosis involves two successive divisions and homologous chromosome separation, while mitosis results in identical diploid cells.

What are sister chromatids?

Duplicated chromosomes in the same cell.

What must happen at the metaphase plate during cell division?

Chromosomes must be aligned and attached to kinetochore microtubules.

What are kinetochores?

Specialized protein complexes that assemble at the centromere regions of the chromosomes.

What types of microtubules are part of the mitotic spindle?

Kinetochore microtubules, non-kinetochore microtubules, and astral microtubules.

What is the primary process during anaphase?

Separation of sister chromatids.

What are cohesins?

Proteins that hold duplicated chromosomes together.

What happens to cohesins during anaphase?

Cohesins are destroyed, allowing sister chromatids to separate.

What is the role of the anaphase-promoting complex/cyclosome (APC/C)?

APC/C regulates the degradation of M-cyclin and securin, facilitating sister chromatid separation.

What happens to APC/C if chromosomes are improperly attached?

APC/C is inhibited, which constitutes a spindle assembly checkpoint.

What are the two processes that occur during anaphase?

Anaphase A and Anaphase B.

What drives chromosome movement during anaphase A?

Depolymerization of microtubules at the (+) end.

What happens during Anaphase B?

Spindle poles are pushed and pulled apart by motor proteins.

What are the key processes during telophase?

Nuclear envelope reassembles and the contractile ring starts to form.

What is the composition of the contractile ring?

Actin and myosin.

How does meiosis produce haploid cells?

By separating homologous chromosomes to create haploid sets during two rounds of division.

What is recombination in meiosis?

The exchange of homologous segments from maternal and paternal chromosomes during prophase I.

What is the difference between metaphase in mitosis and metaphase I in meiosis?

In metaphase I, homologous chromosome pairs align, unlike in mitosis where individual chromosomes align.

What occurs during Anaphase I of meiosis?

Separation of homologous chromosomes, while sister chromatids remain attached.

When do sister chromatids separate during meiosis?

During Anaphase II.

What are the types of genetic reassortment in meiosis?

Independent assortment and recombination.

What can result from errors in chromosome segregation during meiosis?

Gametes with incorrect numbers of chromosomes, potentially leading to conditions like Down syndrome.

What is the significance of the cleavage furrow during cytokinesis?

It marks the physical division of the cell into two daughter cells.

What is the main driving force for chromosome movement in Anaphase A?

Depolymerization of microtubules.

How does the contractile ring contribute to cytokinesis?

It constricts to create the cleavage furrow that separates the two new cells.

What phases does meiosis consist of?

Meiosis I and Meiosis II.

What type of cells does meiosis produce?

Haploid gametes.

Why is meiosis described as two successive mitotic divisions?

It involves chromosome duplication followed by two rounds of division without an intervening S phase.

What is one major outcome of crossing-over during prophase I?

Increased genetic diversity among gametes.

What defines a bivalent structure during meiosis?

A bivalent contains four chromatids from homologous chromosomes.

What controls the contraction of the contractile ring?

Phosphorylation of a regulatory myosin-binding protein.

During which meiotic stage does independent assortment occur?

Metaphase I.

What indicates that a cell is in M phase?

The presence of condensed chromosomes and mitotic spindle formation.

What is the relationship between the nuclear envelope and M-Cdk during telophase?

The nuclear envelope reassembles as M-Cdk activity decreases.

What is the function of the cleavage plane?

It guides the formation of the contractile ring during cytokinesis.

How do microtubule-associated motors contribute during Anaphase B?

They create the pushing and pulling forces that separate the spindle poles.

What happens to sister chromatids in Meiosis II?

They separate into individual chromosomes.

What does successful chromosome attachment trigger during M phase?

Activation of the anaphase-promoting complex/cyclosome (APC/C).

What must occur for APC/C to function properly at the spindle assembly checkpoint?

All chromosomes must be properly attached to the spindle.

In what orientation is the cleavage plane positioned during cytokinesis?

Perpendicular to the long axis of the mitotic spindle.

What is the primary purpose of meiosis in sexual reproduction?

To generate genetic diversity through recombination and independent assortment.