D2.1 Cell Division
No description yet. This curated deck is ready for daily study.
Card preview (24)
What is the purpose of cell division?
To generate new cells for growth, tissue repair, and reproduction.
What is a parent cell vs daughter cell?
Parent/mother cell divides → produces two genetically identical daughter cells (mitosis) or genetically distinct haploid cells (meiosis).
Stages of eukaryotic cell division?
• DNA replication (S phase) → 2. Nuclear division (mitosis/meiosis) → 3. Cytokinesis.
Do prokaryotes undergo mitosis or meiosis?
No; they reproduce asexually via binary fission.
What is a chromosome?
Thread-like DNA molecule containing genetic information.
What are sister chromatids?
Two identical DNA molecules connected at a centromere after replication.
What are cohesins?
Proteins holding sister chromatids together until anaphase.
Difference: chromosome vs chromatid?
Chromosome = single DNA before replication; Chromatid = one of two identical DNA strands post-replication.
How do chromosomes move during division?
Kinetochores attach centromeres → microtubules + motor proteins (kinesins/dyneins) pull chromatids.
How is DNA condensed for division?
DNA wraps around histones → forms chromatin → supercoiling → condensed chromosomes.
Kinesin vs dynein roles?
Kinesin → moves toward kinetochore; Dynein → moves away, regulates spindle length.
Active vs inactive chromatin?
Euchromatin = loose, transcriptionally active; Heterochromatin = tightly packed, inactive.
Role of mitosis?
Produces 2 genetically identical daughter cells; maintains chromosome number.
Phases of mitosis (PMAT)?
Prophase → Metaphase → Anaphase → Telophase.
Malfunctions of mitosis?
Uncontrolled division → cancer.
Prophase key events?
Chromosomes condense, sister chromatids visible, centrosomes move, nuclear envelope breaks down.
Anaphase key events?
Cohesins removed → sister chromatids separate → pulled to opposite poles.
Metaphase key events?
Chromosomes align at equator; kinetochores attach to spindle fibers; motor proteins control movement.
Telophase key events?
Chromosomes decondense, nuclear envelope reforms, cytokinesis occurs.
Mitotic index formula?
Mitotic index = (Cells in mitosis ÷ Total cells).
What is cytokinesis?
Division of cytoplasm to form two daughter cells; occurs after nuclear division.
Cytokinesis in animals vs plants?
Animal → contractile ring (actin/myosin) → cleavage furrow (centripetal). Plant → vesicles form cell plate → grows outward to fuse with cell wall (centrifugal).
Equal vs unequal cytokinesis?
Usually equal, all organelles distributed. Unequal → oogenesis (humans), budding (yeast).
Why is unequal cytokinesis important in oogenesis?
Retains cytoplasm in one ovum → ensures resources for embryonic development; polar bodies disintegrate.