Regulation of Cell Cycle
| English | Chinese | Pinyin |
|---|---|---|
| checkpoint | 检查点 | jiǎn chá diǎn |
| cancer | 癌症 | ái zhèng |
Division must be controlled
- Cells divide to grow and heal — but they must not divide too much.
- Dividing at the wrong time, or with damaged DNA, is dangerous.
- So the cell cycle has built-in controls that can pause it.
- Getting this control right keeps the whole body healthy.
Checkpoints: stop and check
- A checkpoint 检查点 is a point where the cell pauses to check itself.
- Only if everything is in order does the cycle continue.
- If something is wrong, the cell stops and tries to fix it.
- Checkpoints act like quality-control inspectors along the way.
A cell cycle checkpoint is a point where the cell…
A checkpoint halts the cycle to check conditions; the cell continues only if all is well.
What they check
- One checkpoint asks: is the cell big enough and healthy?
- Another asks: was the DNA copied correctly and completely?
- Another asks: are the chromosomes lined up before they separate?
- A failed check halts division until the problem is solved.
Cell cycle checkpoints
Step through the checkpoints — each is a stop-and-check that only lets the cell go on if all is well.
What might a checkpoint check for?
Checkpoints check for things like DNA damage, cell size, and correct DNA copying before allowing division.
When control fails: cancer
- If checkpoints stop working, a cell can divide out of control.
- Uncontrolled division builds a lump of cells — a tumour.
- This runaway growth is what we call cancer 癌症.
- Healthy checkpoints are the body's defence against it.
What can happen if cell cycle control fails?
If checkpoints fail, cells divide without control — this uncontrolled growth is cancer.
Checkpoints help prevent damaged cells from dividing.
By stopping a damaged cell, a checkpoint protects the body from passing on faulty cells.
Select all true statements about cell cycle regulation.
Checkpoints slow or stop division when needed; they do not speed it up. The other three are correct.
A checkpoint failure is serious. If the controls that pause a damaged cell break, that cell divides again and again, passing on its faults — the start of cancer. The whole point of regulation is to catch problems before division.
Catching damaged DNA:
- Suppose a cell's DNA is damaged by UV light from the sun.
- At the next checkpoint, the cell detects the damage and halts.
- It either repairs the DNA or self-destructs — stopping a faulty cell from ever dividing.
The cell cycle is regulated by checkpoints — pauses where the cell checks that conditions (size, DNA copying, chromosome alignment) are correct before continuing. If this control fails, cells divide uncontrollably, which can lead to a tumour and cancer. Checkpoints protect the body by stopping damaged cells.