11.2 the eukaryotic cell division cycle is regulated

Question 1

Cell Cycle Phases

Answer 1

-The cell cycle comprises phases leading to cell division.
-Phases include interphase and M phase (mitosis and cytokinesis).

Question 2

Interphase

Answer 2

-Nucleus is visible, and cell functions occur.
-Divided into three subphases: G1, S, G2.

Question 3

G1 Phase

Answer 3

-Chromosomes are single (unreplicated).
-Ends at G1-to-S transition, committing to DNA replication.

Question 4

S Phase

Answer 4

-DNA replication occurs; sister chromatids remain together until mitosis.

Question 5

G2 Phase

Answer 5

-Cell prepares for mitosis by synthesizing structures moving chromatids.

Question 6

M Phase

Answer 6

-Includes mitosis (division of the nucleus) and cytokinesis (division of the cytoplasm).

Question 7

Cell Cycle Regulation

Answer 7

-Specific signals trigger transitions between phases.
-Progress controlled by cyclin-dependent kinases (CDKs).

Question 8

CDK Activation

Answer 8

-CDK activated by binding to cyclin, altering shape and exposing the active site.
-Protein kinases catalyze phosphorylation, changing protein shape and function.

Question 9

Control Points

Answer 9

-Restriction point (R) controls G1-to-S transition.
-Progress beyond R depends on retinoblastoma protein (RB).

Question 10

Regulation Mechanisms

Answer 10

-Presence or absence of cyclins regulate CDK activity.
-Cyclins synthesized at specific times in the cell cycle, influencing progression.

Question 11

Cell Cycle Checkpoints

Answer 11

-Cyclin-CDKs act at checkpoints to regulate cell cycle progress.
-External signals stimulate or inhibit cell division.

Question 12

External Signals

Answer 12

-Growth factors, like platelet-derived growth factor, stimulate cell division.
-Signal transduction pathways activate cyclin synthesis and CDKs, initiating the cell cycle.