Cell Cycle

Question 1

G0 Cell Cycle Outline

Answer 1

Terminally differentiated cells (cell can’t proliferate, continue in cell cycle)

Question 2

G1 Cell Cycle Outline

Answer 2

All cellular content (excluding chromosomes) are duplicated. Feeds to S

Question 3

Synthesis Cell Cycle Outline

Answer 3

Duplication of all 46 chromosomes. Feeds to G2

Question 4

G2 Cell Cycle Outline

Answer 4

Check DNA for damage (proliferation/termination signals). Feeds into mitosis

Question 5

Effects of cell cycle pathway dysregulation

Answer 5

Uncontrolled proliferation of cells (cancer)

Question 6

Redundant Signaling Pathways Effect

Answer 6

Multiple pro and anti proliferation signals. Targeting 1 signaling pathway won’t kill cancer

Question 7

4 possible signals for cells to receive

Answer 7

Death cues, Survival cues, Proliferation cues & Growth inhibition cues

Question 8

What signals do a cancer cells inherit

Answer 8

Survival and proliferation

Question 9

Types of Extracellular Signalling

Answer 9

Autocrine, Paracrine & Endocrine

Question 10

Pro-oncogene Outline

Answer 10

Non-mutated (natural/healthy) version of an oncogene

Question 11

Mitogens Outline

Answer 11

Promotes cell Division: Inhibits anti-proliferation pathways

Question 12

Growth Factors Outline

Answer 12

Promotes Cell Division: Stimulates protein synthesis and Inhibits protein degradation

Question 13

Survival Factors Outline

Answer 13

Promotes Cell Survival: Suppress apoptosis

Question 14

Cell Cycle Checkpoint Outline

Answer 14

Temporary breaks in cell cycle to assess if progress is viable (ie do we have all necessary materials in necessary amounts, is DNA damaged

Question 15

Main Cancer Checkpoint

Answer 15

G1-S. Allows to progress to S stage despite DNA damage

Question 16

Cyclins Levels in Cell Cycle

Answer 16

Expressed at different levels in cell cycle

Question 17

Cyclin Dependent Kinase

Answer 17

Expressed at same levels throughout cell cycle

Question 18

G1 Cyclins

Answer 18

Promote passage through G1 Restriction Point

Question 18

G1-S Cyclins

Answer 18

Binds Cdks at G1 committing cell to DNA Replication

Question 18

S Cyclins

Answer 18

Binds CdKs during S phase of DNA Replication

Question 19

M Cyclins

Answer 19

binds Cdks to promote mitosis

Question 20

CDK Catalytic Subunit Outline

Answer 20

Performs kinase activity when bound to cyclin

Question 20

Cyclin Substrate

Answer 20

Regulatory subunit, that allows CDK activity when bound

Question 21

E2F G->S Phase

Answer 21

Rb complex phosphorylated by CDK4/6 / CyclinD & releases E2F. E2F binds genome and activates enzymes for DNA synthesis

Question 22

Function of CyclinD / CDK4/6

Answer 22

Phosphorylates Rb component of inactive Rb / E2F. Causes Rb to release E2F

Question 23

E2F M-to-G1

Answer 23

Rb dephosphorylated and left free to bind to E2F. Inactivating it reducing transcriptions

Question 24

p16 Function

Answer 24

Naturally inhibits Cad4/Cyclin D1 Complex. Ensures E2F stays inactive, ensures S phase can't be entered

Question 25

CdK4 Outline

Answer 25

Proto-oncogene, if not regulated. Tumour activity

Question 26

Mantle Cell Lymphoma Outline

Answer 26

Chromosomal translocation places cyclin D1under control of IgH control. Results in upregulated proliferation of B lymphocytes

Question 27

p53 Outline

Answer 27

Transcription factor activated by DNA damage, creates p21 inhibits cyclin-cdk (inhibits phosphorylation of Rb and progression to S stage). Mutation results in cancer, unproliferated

Question 28

Mutation in p53 Outcomes

Answer 28

Damaged DNA continues to replicate = further mutations occur in DNA = Progression of cancer

Question 29

Apoptosis Outline

Answer 29

Programmed cell death with no damage to surrounding area. Single cell shrinks forming apoptotic body (due to pro-apoptotic proteins). Chromatin condensed and DNA undergoes non-random fragmentation

Question 30

Necrosis Outline

Answer 30

Damage by external force causes cell death. Cell swells and leaks it's contents resulting in inflammation. DNA is randomly degraded

Question 31

Trophic Factors Outline

Answer 31

External survival/growth signals in their absence apoptosis pathway is activated

Question 32

'Healthy' Apoptosis

Answer 32

At 16 weeks gestation, apaoptosis occurs on feet and hands to form distinct digits

Question 33

Intrinsic Apoptotic Cause

Answer 33

Occurs when extent of damage exceed capability of fixing (DNA integrity is damaged)

Question 34

Extrinsic Apoptotic Pathway

Answer 34

Ligand-receptor binding forms Death-Inducing Cell Signaling (DISC), causing receptor trimerisation. Activates Caspase 8 (initiator) which in turn stimulates caspases

Question 35

BcL2 Outline

Answer 35

Anti-apoptotic proteins. Bound by functional p53 and inactivated, permeabilizing mitochondrial membranes and releasing Cytochrome C

Question 36

Formation of Apotosome

Answer 36

Cyt C binds Apaf 1 forming complex that binds to Caspase 9

Question 37

Caspase Action Summary

Answer 37

Cleaved in response to activation signals

Question 38

Activated Capsase Action

Answer 38

Endonuclease DNA fragmentation, organelle breakdown, apoptotic bodies (to be phagocytosed)

Question 39

How To Over-ride intrinsic pathways

Answer 39

p53 and BLC2 Mutation

Question 40

Decoy Receptors

Answer 40

Binds to death ligands ensuring DISC Complex isn't formed