Cell cycle MCQs

What is true about lamins?

They contain a nuclear localization signal, are components of the nuclear lamina, are intermediate filament proteins, and are mutated in Hutchinson-Gilford progeria syndrome

What is phosphorylation?

Addition of a phosphate group to an amino acid (commonly serine, threonine or tyrosine) or a lipid

How does cell division differ between prokaryotes and eukaryotes?

Eukaryotes undergo meiosis for gametes and mitosis for other dividing cells, prokaryotes divide by binary fission

How is the cell cycle coordinated?

By phosphorylation and dephosphorylation, checkpoints, cyclin expression, and cyclin-dependent kinases

How are cyclins activated and deactivated?

By phosphorylation/dephosphorylation, Cdc25 action, ubiquitination, and proteasomal degradation

Which Cyclin/Cdk combinations are active during the cell cycle?

G0/G1: Cyclin D-CDK4/6; S: Cyclin A/CDK2; G2: Cyclin A/CDK1; M: Cyclin B/Cdk1

How is the G1 checkpoint regulated?

Rb binds E2F and prevents gene transcription

What happens at the G1 checkpoint after DNA damage?

Chk2 activates p53, p53 activates p21, and p21 inhibits CDK2

What stages does mitosis consist of?

Prophase, metaphase, anaphase, telophase, and cytokinesis

Prophase, metaphase, anaphase, telophase, and cytokinesis

Cdc25

What is the S-phase checkpoint?

A surveillance mechanism responding to DNA damage and replication perturbations, mediated by ATR and Chk2

What does the spindle checkpoint detect?

Lack of microtubule attachment to chromosomes

What happens when the spindle checkpoint is activated?

MAD-2 inhibits destruction of Cyclin B and keeps MPF inactive