module 12: cell division

What is the function of cohesin during cell division?

Cohesin holds sister chromatids together after replication through G2 and into mitosis.

What are the two main types of cell division in eukaryotes?

Mitosis and meiosis.

What is the M phase of the cell cycle?

The phase that includes mitosis and cytokinesis.

What are the stages of interphase?

G1 (growth and metabolism), S (DNA replication), and G2 (preparation for mitosis).

What type of cells are permanently non-dividing?

Highly specialized cells like nerve cells, muscle cells, and red blood cells.

What triggers entry into M phase?

Activation of maturation-promoting factor (MPF), which consists of a kinase and cyclin.

What are cyclin-dependent kinases (Cdks)?

Kinases that regulate cell cycle transitions, such as START and G2/M.

What do checkpoints in the cell cycle do?

Ensure accurate and orderly progression through the cell cycle by arresting it if problems are detected.

What is mitosis?

A process of nuclear division resulting in two genetically identical nuclei.

What are the stages of mitosis?

Prophase, Prometaphase, Metaphase, Anaphase, Telophase.

What happens during prophase?

Chromosomes condense, mitotic machinery assembles, cohesin holds chromatids.

What are centromeres and kinetochores?

Centromeres are constrictions on chromosomes, kinetochores are protein complexes where microtubules attach.

What happens to the nuclear envelope in prophase?

It is disassembled to allow spindle interaction with chromosomes.

What is prometaphase characterized by?

Completion of spindle assembly and chromosome movement to the cell center.

What occurs during metaphase?

Chromosomes align at the metaphase plate; spindle fibers attach to kinetochores.

What happens in anaphase A and B?

A: Chromosomes move to poles; B: Spindle poles move apart.

What happens during telophase?

Spindle disassembles, nuclear envelopes reform, chromosomes decondense.

What is cytokinesis?

Division of the cytoplasm to form two daughter cells, driven by a contractile ring.

What motor proteins are involved in mitosis?

Dynein and kinesin-related proteins.

What is unique about plant cell division?

Formation of a cell plate guided by a phragmoplast instead of a cleavage furrow.

What is the preprophase band?

A ring of microtubules and proteins in plant cells marking the future division site.

What is meiosis?

A type of cell division producing haploid cells from a diploid parent.

What happens during meiosis I?

Homologous chromosomes pair, recombine, and segregate.

What occurs in meiosis II?

Separation of sister chromatids resulting in four haploid cells.

What is the difference between gametic, zygotic, and sporic meiosis?

Gametic: meiosis during gamete formation (animals), Zygotic: meiosis after fertilization (fungi), Sporic: meiosis in diploid sporophyte (plants).

What happens during prophase I of meiosis?

Synapsis, recombination, and chromosomal condensation (leptotene to diakinesis).

What occurs during metaphase I?

Homologous chromosomes align at the metaphase plate.

What happens in anaphase I?

Homologous chromosomes separate to opposite poles.

What is interkinesis?

The brief interphase-like stage between meiosis I and II.

What occurs during telophase I?

Some cells reform nuclear envelopes; prepares for meiosis II.