🧬 Biology · Genetics
Mitosis and the Cell Cycle cheat sheet
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The cell cycle
- Interphase = G1 (grow, work) + S (copy DNA) + G2 (get ready)
- M phase = mitosis (PMAT) + cytokinesis
- In a typical dividing cell, interphase takes up much more of the cycle
PMAT
- Prophase: chromosomes coil up, nuclear envelope breaks down, spindle forms
- Metaphase: chromosomes line up in the middle
- Anaphase: sister chromatids separate and move to opposite poles
- Telophase: two nuclei re-form, chromosomes uncoil
Cytokinesis
- Divides the cytoplasm
- Animal cell: cleavage furrow (pinches in)
- Plant cell: cell plate (builds a new wall)
- Usually begins in late anaphase or telophase
Counting in a human body cell
- G1: 46 chromosomes, no sister chromatids
- End of S phase to metaphase: 46 chromosomes, 92 chromatids
- Anaphase and telophase: 92 chromosomes in the cell (46 at each pole) until cytokinesis is complete
- Each daughter cell: 46 chromosomes
The result
- Two genetically identical daughter cells
- Same chromosome number as the parent cell
Formulas
- Chromatids while sisters are joined: chromatids = 2 × chromosomes (end of S phase through metaphase)
- Chromosomes in the cell in anaphase: 2 × the number in G1 (for example 46 → 92)
- Chromosomes in each daughter cell: the same as the parent cell had in G1 (for example 46 → 46)
Mitosis and the Cell Cycle cheat sheet from HighSchoolQ.com, for personal study use.