Cell cycle
The ordered series of events from one cell division to the next. Interphase (G1, S, G2) is when the cell grows and copies its DNA in S phase. The M phase is mitosis plus cytokinesis.
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Analogy
A factory shift: prepare, copy the plans, check them, then split into two factories.
In practice
Skin cells divide often. Mature nerve cells stay in a resting phase called G0 and rarely divide.
Practice
Flashcards
- What happens in S phase?The cell copies its DNA.
Interview questions
- Explain how checkpoints control the cell cycle and what happens when the control fails.
- Checkpoints at G1, G2 and M
- Cyclins and CDKs drive progress
- p53 stops damaged cells
- Mutation in brakes or accelerators leads to cancer
Questions people ask
How long does the cell cycle take?
It depends on the cell. A fast-dividing human cell in culture may take about 24 hours, with S phase around 8 hours and mitosis only about an hour. Early embryo cells can divide in far less time. Some cells, such as mature neurons, leave the cycle altogether.
What is the G0 phase?
G0 is a resting state outside the active cycle. Cells enter it from G1 when they do not receive growth signals, or when they have specialised. Some cells, such as liver cells, can re-enter the cycle if needed. Others, such as mature neurons, normally stay in G0 for life.