Cell Cycle Regulation: p53 and RB Proteins

Questions and Answers

The molecule of the year

The tumor suppressor gene

The cell cycle regulator

The guardian of the genome (correct)

To inhibit CDK (correct)

To activate DNA replication

To produce proteins that block the cell cycle

To bind DNA directly

The cell cycle is blocked

Cancer is more likely to occur (correct)

DNA replication is activated

The genome is protected

Greater than 50% Signup and view all the answers

To regulate the cell cycle Signup and view all the answers

They are both tumor suppressor genes Signup and view all the answers

The genome is at a higher risk of mutation Signup and view all the answers

It is highly important in regulating the cell cycle Signup and view all the answers

Because a defect in it can lead to retinoblastoma Signup and view all the answers

It does not lead to cancer when defected Signup and view all the answers

They gain the ability to regenerate their limbs Signup and view all the answers

So cells can only divide when it's appropriate Signup and view all the answers

A lot of energy and protein machinery Signup and view all the answers

So cells can divide only when appropriate Signup and view all the answers

Study Notes

P53, a key protein, regulates the cell cycle at a higher level, earning it the nickname "guardian of the genome."
P53 binds DNA directly to produce proteins that block the progression of the cell cycle.
One of these proteins is p21, which functions to inhibit CDK, preventing DNA replication or activation of mitosis.

P53 and RB are considered tumor suppressor genes, which are essential for regulating the cell cycle.
Defects or mutations in these genes can lead to loss of function, increasing the risk of cancer.
Over 50% of tumors have a defect in p53, highlighting its importance in preventing cancer.

P21 is unusual in that its defect does not lead to cancer, but rather allows mice to regenerate their limbs.
Scientists are still trying to understand the mechanisms behind p21's function.

Tumor suppressor genes are crucial for regulating the cell cycle, ensuring that cells divide only when appropriate.
Mitosis, or cell division, requires significant energy and protein machinery, making it essential to regulate the process accurately.