Cell Cycle Unit I Biochemistry

Front 1

What are the stages of the cell cycle?

Back 1

Mitosis and interphase
Interphase contains (G1, S, and G2 phases)

Front 2

What occurs during the S phase?

Back 2

Replication of nuclear DNA (i.e.) chromosomes
Cells contain athe diploid number (2n) amount of DNA before S phase; after S, the amount of DNA is doubled (4n) in preparation for cell division

Front 3

Duplicated chromosomes consist of two identical chromatids called ___________

Back 3

Sister chromatids

Front 4

What occurs during the G2 Phase?

Back 4

Metabolism of RNA, regulatory proteins and enzymes necessary for mitosis to take place
DNA is analyzed for possible errors and errors are corrected before mitosis
During this period, the cell has two complete diploid sets of chromosomes

Front 5

What occurs during the G1 Phase?

Back 5

Cell volume is restored to normal 2n DNA
Metabolism of RNA, regulatory proteins, and enzymes necessary for DNA replication
Cells can withdraw from the cell cycle into G0 (outside) during G1 and stop dividing for long periods of time or indefinitely.

Front 6

3 types of experimental systems for cell cycle research

Back 6

Biochemical analysis of animal eggs and embryos
Identification of yeast cell division cycle mutants
Mammalian cell fusion experiments

Front 7

MPF (Mitosis Promoting Factor) is required for: (4)

Back 7

Chromatin condensation
Nuclear envelope breakdown
Fragmentation of ER and Golgi apparatus
Reorganization of microtubules to form the mitotic spindle

Front 8

What parallels MPF activity?

Back 8

Cyclin B Levels

Front 9

What happens when cells are treated with cyclohexamide?

Back 9

Protein synthesis is required for MPF and cyclin B, treatment blocks cyclin B synthesis, chromosome condensation and nuclear envelope breakdown.

Front 10

MPF is a complex consisting of:

Back 10

cyclin B and a cyclin dependent kinase (M-Cdk)

Front 11

What effects do Cdc25 and Wee1 have on MPF?

Back 11

Cdc25 and Wee1 have opposing effects on MPF. Wee1 inhibits MPF while Cdc25 stimulates activity.

Front 12

Name the 3 checkpoints in the cell cycle, where they are and what they check for.

Back 12

G1 to S phase transition (Is the environment favorable?)
G2 to M phase transition (Is all DNA replicated?, Is environment favorable?)
Metaphase checkpoint (Are all chromosomes attached to the spindle?)

Front 13

Cyclin dependent Kinases (Cdks) What do they do?

Back 13

Activity rises and falls through the cycle and lead to cyclic changes in the phosphorylation of intracellular proteins that initiate or regulate the major events of the cell cycle.

Front 14

Cyclins: What do they do?

Back 14

Bind to Cdks to cyclically regulate their activity. Cdks are dependent on cyclins for their activity. Cyclin levels undergo a cycle of synthesis and degradation with each cell cycle.

Front 15

Four classes of cyclns and what they do.

Back 15

G1/S cyclins bind to CdKs at the end of G1 and commit the cell to DNA replication
S-cyclins bind Cdks during S phase and are required for the initiation of DNA replication.
M-cyclins prompote the events of mitosis
G1 cyclins help promote the passage through start or the restriction point in late G1

Front 16

Two ways in which the Cell cycle is controlled with cyclins

Back 16

Proeteolysis of cyclins- cyclins are destroyed by a ubiquitin dependent mechanism that marks the protein for destruction
Transcription- Cyclin levels controlled by changes in cyclin gene transcription and cyclin synthesis

Front 17

What does SCF do?

Back 17

Ubiquitynates G1/S cyclins and certain CKI proteins that control S-phase initiation. SCF activity is regulated by the phosphorylation status of target proteins.

Front 18

What does Anaphase promoting complex (APC) do?

Back 18

Ubiquitynates M cyclins and other regulators of mitosis. APC activity is regulated at different stages in the cell cycle via the addition of specific subunits.