Summary
Control points at G1/S, G2/M and metaphase that halt the cycle until DNA and spindle attachments are correct.
In depth
The G1/S checkpoint checks cell size, nutrients and DNA damage; p53 can halt the cycle by inducing p21. The G2/M checkpoint checks that DNA is fully replicated and undamaged. The spindle assembly checkpoint at metaphase ensures every kinetochore is attached before anaphase.
If damage cannot be repaired, cells may enter senescence or apoptosis.
p53 is called the guardian of the genome; it is stabilised after DNA damage by phosphorylation (via ATM and ATR kinases) and turns on genes for arrest, repair or apoptosis. More than half of human cancers have p53 mutations, and Li-Fraumeni syndrome, with one inherited faulty copy, causes a high cancer risk.
The spindle checkpoint keeps an inhibitor on the anaphase promoting complex until the last chromosome is correctly attached, which prevents aneuploidy. Checkpoints can be seen as pauses to repair, not as stop signs for ever.
Frequently asked questions
What is Cell Cycle Checkpoints?
Control points at G1/S, G2/M and metaphase that halt the cycle until DNA and spindle attachments are correct.
Which area of biology covers Cell Cycle Checkpoints, and how advanced is it?
Cell Cycle Checkpoints is one of the 52 topics in Cell Biology. It is rated Advanced, so it suits learners who want specialist depth. Related topics in this area include Meiosis, Telomeres and Senescence, Cyclin-Dependent Kinases.
Why does Cell Cycle Checkpoints matter?
Radiotherapy and many chemotherapies work by damaging DNA in cells whose checkpoints no longer work properly.
Can you give an example of Cell Cycle Checkpoints?
Loss of p53, mutated in more than half of human cancers, lets damaged cells keep dividing.
What should I learn before Cell Cycle Checkpoints?
Work through the Beginner topics in Cell Biology first, such as Cell Theory, Prokaryotic Cell, Eukaryotic Cell, then return to Cell Cycle Checkpoints. Advanced topics assume the Intermediate vocabulary.
What topics are related to Cell Cycle Checkpoints?
The closest topics to Cell Cycle Checkpoints are Meiosis, Telomeres and Senescence, Cyclin-Dependent Kinases, Cell Cycle. Comparing them side by side is a good way to see how the ideas connect.
How can I check that I understand Cell Cycle Checkpoints?
Read the summary and the in-depth section, then use the quick check on the interactive lesson for Cell Cycle Checkpoints. To practise the whole of Cell Biology, use the Cell Biology quiz.
How is Cell Cycle Checkpoints different from Meiosis?
Cell Cycle Checkpoints: Control points at G1/S, G2/M and metaphase that halt the cycle until DNA and spindle attachments are correct. Meiosis: Two rounds of division that halve chromosome number to form genetically varied haploid gametes. Read both side by side and note what each one explains.
How should I study Cell Cycle Checkpoints step by step?
First, read the summary and write the definition in your own words. Second, read the in-depth section and note any example. Third, compare it with Meiosis and explain the difference aloud. Finally, take the Cell Biology quiz and come back to this page for any question you miss.