1.2.2: Mitosis and the cell cycle
Not started yet — this one needs some love.
The cell cycle has three overall stages:
Growth: the cell grows and makes more sub-cellular structures (ribosomes, mitochondria); DNA replicates so each chromosome is copied.
Mitosis: one copy of each chromosome is pulled to each end of the cell; the nucleus divides.
Cytokinesis: the cytoplasm and cell membrane divide → two genetically identical daughter cells, each with the same chromosome number as the parent.
Uses of mitosis: growth, repair and replacement of cells, and asexual reproduction.
You need the three overall stages — the individual phases of mitosis (prophase, metaphase, etc.) are not required.
Common exam mistakes
'Chromosomes pull apart' or 'DNA moves to the sides' is too vague — say one set of chromosomes is pulled to each end of the cell.
Do not say all chromosomes move to one end — one set goes to each end, so both daughter cells get a full set.
In stage 1, sub-cellular structures replicate/increase in number — do not say they 'divide'. DNA replicates (or makes copies) during this stage; 'multiplies' and 'reproduces' were not accepted by examiners.
When asked specifically about stage 1 (growth), describe only cell growth and DNA replication — do not describe chromosome movement or cell division; those belong to stages 2 and 3.
Mitosis produces 2 identical diploid cells — do not confuse with meiosis (4 genetically different haploid cells).
Avoid writing daughter cells are 'similar' or 'copies' — they are genetically identical: same chromosome number and same DNA sequence as the parent.