Cell Cycle Control Lecture

This set of flashcards covers major concepts and details from the lecture on cell cycle control, focusing on genetic screens, key proteins, and regulatory mechanisms.

What is the main focus of the lecture on 9/29/25?

Cell cycle control.

Who were the recipients of the Nobel Prize in Physiology or Medicine in 2001?

Leland H. Hartwell, Tim Hunt, and Sir Paul Nurse.

What is a genetic screen?

A method for finding genes that contribute to some trait or phenotype by causing random mutations throughout the genome.

What did the saturation screens achieve?

They mutated and tested every gene in the genome multiple times.

What happens when DNA damage occurs in cells?

Cells can either arrest division or become mutants that cannot properly respond to DNA damage.

What are the categories of temperature sensitive mutants?

Mutants fall into categories based on their common phenotypes related to cell division.

What regulates the cell cycle?

Cyclins and cyclin-dependent kinases (CDK) control progression through the cell cycle.

What role does p53 play in the cell cycle?

p53 detects DNA damage and blocks progression through the cell cycle if damage is present.

What is the G1 checkpoint's significance?

It is a fundamental decision point for cell division; cells become committed to division once they pass it.

What happens to CDKIs during DNA damage?

CDKI expression increases to block the progression of the cell cycle.

How do cyclins control cell division?

Cyclins bind to and activate CDKs, which then phosphorylate target proteins to promote cell division.

What could block the cell cycle progression?

Activation of CDKIs, reduction of cyclin levels, blockage of signaling pathways for cyclin expression.

What is the effect of ubiquitin-dependent proteolysis on cyclin levels?

It causes the degradation of cyclin proteins, thus reducing their levels.

What does a rise in cyclin levels indicate?

It indicates that the cell is preparing to progress through the cell cycle.

What happens at the G2 checkpoint?

DNA damage is checked; if no damage is present, the cell can divide.

What is Rb and how does it function in the cell cycle?

Rb is a protein that, when phosphorylated by CDKs, releases E2F, allowing for the activation of genes required for the S phase.