AP Biology: Regulation of the Cell Cycle

Define checkpoint.

A validation stage in where regulatory proteins make sure that requirements are met for a cell to move onto the next stage in the cell cycle.

What are the three checkpoints in the cell cycle?

The G1 checkpoint, G2 checkpoint, and the M checkpoint.

Why are the checkpoints put in place where they are? (check with armpit later)

The G1 checkpoint checks that there is enough room for more cells and if there is an adequate supply of energy and materials available. S is kind of like the no return point it will either be destroyed or will move on. If the cell doesn’t meet the requirements then it will enter G0, where the cell cycle just completely stops. The G2 checkpoint checks to see if DNA replicated properly and if there are enough materials for mitosis. It checks because mitosis is a huge part of making the daughter cells are equipped properly. The M checkpoint sees if the centromeres aligned with the spindle fibers, this leads to anaphase. The separation of the chromosomes is pretty important for the correct distribution of DNA.

Define cyclins.

a group of signal proteins that activate CDKs (autocrine). Only active in the cell cycle, their production is controlled by extracellular signal transduction.

Define cyclin-dependent kinases (CDKs).

Literally cyclin-dependent kinases that phosphorylate target proteins that can allow the cell to move through the checkpoints.

Define maturation promotion factor

An activated CDK (CDK + cyclin).

Define mitogen (cycle cell regulators)

a substance that stimulates mitosis.

Provide examples of mitogens

Some examples are growth hormones (endocrine); induce cell reproduction to grow, cell to cell signals (paracrine); induce cell reproduction to heal

What is the trend of cyclin production throughout the cell cycle

It increases during interphase and decreases during mitosis. Also, there’s a positive correlation between cyclin and MPF.

How do MPFs work

see graph

Define cancer

the unregulated growth of cells, as age increases, cancer rates increases.

Cancer is caused by the mutation of one of the two genes involved with cell regulation, what are the two genes

proto-oncogenic and tumor supressor genes

Define proto-oncogenic genes

A gene that codes for dominant traits (only need one copy to express it), normally coding for cyclins, CDKs, or receptors. An example would be the HER2 gene, which codes for human epidermal growth factor receptor 2n (leads to beast cancer).

Define tumor supressor genes

A gene that codes for recessive traits (meaning you need 2 copies to express it), the brake of the cell cycle. Transcribes proteins involves with cyclin and CDK reaction. An example would be BRCA1 and BRCA2 which ensure stability of a cells genetic material (results in breast cancer)

Define carcinogens

substances that cause cancer