Cell Division Flashcards

Prophase, Metaphase, Anaphase, Telophase (PMAT).

Meiosis has two divisions producing four haploid, genetically unique cells; mitosis has one division producing two identical diploid cells.

The cell replicates its entire genome, forming sister chromatids joined at the centromere.

Whether the cell has adequate size, nutrients, and growth factors to enter S phase. If not, the cell enters G0.

Exchange of genetic material between non-sister chromatids of homologous chromosomes during prophase I, increasing genetic diversity.

Microtubule structure that attaches to kinetochores and separates chromosomes to opposite poles during division.

Animal cells use a cleavage furrow (actin/myosin contractile ring); plant cells build a cell plate from Golgi vesicles.

Failure of chromosomes to separate properly during division, producing aneuploid cells (e.g., trisomy 21 / Down syndrome).

Cyclins fluctuate in concentration and activate CDKs, which phosphorylate target proteins to drive the cell through each phase.

Random orientation of homologous pairs at the metaphase plate in meiosis I, producing 2^n possible gamete combinations.

Homologous chromosomes synapse to form tetrads, crossing over occurs, the nuclear envelope breaks down, and the spindle forms.

Tumor suppressor that halts the cell cycle at G1/S when DNA damage is detected; triggers apoptosis if damage is irreparable.

Diploid (2n) cells have two chromosome sets; haploid (n) cells have one. In humans: somatic = 46, gametes = 23.

Centromeres split and sister chromatids are pulled to opposite poles in haploid cells.

The cell grows, synthesizes proteins for division (e.g., tubulin), and checks for DNA replication errors before entering mitosis.

Proto-oncogenes promote cell division (gain-of-function mutations cause cancer); tumor suppressors inhibit division or trigger apoptosis (loss-of-function mutations cause cancer).

A group of four chromatids formed when two homologous chromosomes pair during synapsis in prophase I; site of crossing over.

That all chromosomes are properly attached to spindle fibers and aligned at the metaphase plate before anaphase begins.

Binary fission is prokaryotic cell division without a spindle, condensed chromosomes, or nuclear envelope. The circular chromosome replicates and the cell splits.

It produces haploid gametes so fertilization restores the diploid number, and generates genetic variation via crossing over and independent assortment.

Two identical copies of a chromosome produced during S phase, held together at the centromere by cohesin proteins until anaphase.

Programmed cell death triggered by caspase enzymes when checkpoints detect irreparable damage, preventing proliferation of defective cells.

Meiosis I separates homologous chromosomes (reduction division, 2n to n); meiosis II separates sister chromatids (equational division, maintains n).

Protein structures on centromeres that attach to spindle microtubules and move chromosomes toward poles during anaphase.

G1 (cell growth), S (DNA replication), and G2 (preparation for mitosis). Interphase occupies ~90% of the cell cycle.