6: Cell Division Mitosis and Meiosis Flashcards
What is Mitosis?
Functions in the growth and repair of body cells, actual division of a nucleus. Split into prophase, metaphase, anaphase, telophase.
What is Meiosis?
Produces gametes, with half the chromosome. Sex cells. Occurs in two stages Meiosis I and II.
What is a Chromosome?
Condensed strand of DNA.
What are sister Chromatids?
A replicated chromosome where the two are exact copies of each other.
What is a Centromere?
A specialized region that holds sister chromatids together.
What is the Cell Cycle?
The sequence of growth and division cells must go through.
Cytokinesis
Division of cytoplasm.
Checkpoint
Where specialized proteins assess whether that cell is ready to proceed to next stage.
G-1 / First Gap Phase
After mitosis, cell increases in size and prepares to replicate its DNA.
G-1 Checkpoint Criteria
DNA is healthy and undamaged.
S-Phase
DNA synthesized through replication.
S-Phase Checkpoint Criteria
No replication errors.
G-2 Phase / Second Gap Phase
Cell must produce organelles and other cellular components that will go into daughter cells.
G-2 Phase Checkpoint Criteria
Cell must be completely replicated and ready for another stage of Mitosis.
Interphase
Chromosomes replicate to get ready for cell division.
Prophase
1st stage: Chromosomes become visible, nucleoli disappear, Spindle fibers form, centrioles migrate to poles, nuclear membrane begins to disappear.
Metaphase
2nd stage: Chromosomes line up single file on metaphase plate, centrosomes at opposite poles, spindle fibers go from centrosomes to centromeres of chromosomes.
Anaphase
3rd stage: Centromeres separate, spindle fibers pull sister chromosomes apart.
Telophase
4th stage: Chromosomes cluster at opposite ends, nuclear membrane re-forms. Chromosomes unravel to pre-split condition. Nuclear membrane re-forms.
Meiosis I
Reduction division: Synapsis and Crossing over.
Meiosis II
Similar to mitosis.
Cytokinesis
Division of cytoplasm. Cleavage furrow forms down middle separating daughter chromosomes, cell plate forms down middle. Middle lamella sticks them together.
