2.1.6 Mitosis Flashcards
Chromatin is…
DNA dispersed through the nucleus of a cell during interphase
Mitosis step 1, prophase
Two pairs of chromosomes; each replicated to form two chromatids; DNA condenses so sister chromatids are visible inside the nucleus
Mitosis step 2, metaphase
Nuclear envelope breaks down, is no longer visible; centrioles move to poles of the cell; centrioles start to anchor spindle fibres to the chromatids; chromatids line up at the equator of the cell
Mitosis step 3a, early anaphase
Each chromosome is attached at the centromere to a spindle fibre; fibres shorten and appear to pul the chromatids apart by their centromeres; centromeres are split in half
Centromere?
Centre binding part of a chromatid
Mitosis step 3b, middle anaphase?
Chromatids are now chromosomes; they migrate to opposite ends of the cell as spindle fibres shorten
Mitosis step 3c, late anaphase
There is an identical full set of chromosomes at each end of the cell; cytoplasm may begin to divide
Mitosis step 4, telophase?
Final stage of mitosis; nucleus envelope reforms; division spindle breaks down; cleavage furrow forms; chromosomes become less distinct as DNA disperses
Cleavage furrow?
Cytoplasm of cell begins to pinch in in centre
PMAT?
Prophase, metaphase, anaphase, telophase
(NOT MITOSIS) cytokinesis?
Cytoplasm divides and two new cells are formed; chromosomes revert to elongated shape and cannot be distinguished; new cells move into interphase; each new cell has a full set of chromosomes identical to the parent cell
2 daughter cells are…
Diploid
Diploid?
Containing the full genetic information; 46 chromosomes; somatic cells
Haploid?
Containing half the genetic information; 23 chromosomes; gametes
Mitosis differences in plant cells?
Cell plate forms at equator, new cell wall; no centrioles, spindle fibres anchored at ends of walls; only meristem cells are capable of mitosis (thinner cell walls)
Mitotic index equation?
Number of cells with condensed chromosomes
MI= —————————————————————— x 100
Total number of cells
