Cancer And Cell Cycle

Front 1

What is the difference between a tumor and a cancer?

Back 1

A tumor is a swelling or lesion caused by abnormal cell growth lacking contact inhibition. It is only considered a Cancer if it is malignant (i.e. is invasive, destructive & has the ability to metastasise)

Front 2

What does the term Malignant mean in relation to a tumor?

Back 2

It is invasive, destructive and has the ability to metatstatise

Front 3

In what ways can metastasis occur?

Back 3

Haematogenically (Bloodstream), Lymphogenically (Lymphatic System), Across body cavities (Transcoelomic spread)

Front 4

Define the Cell Cycle

Back 4

The name given to the activities of the cell from it’s production, to the production of its own progeny

Front 5

How long does the Cell Cycle last on average?

Back 5

22hours

Front 6

What are the two main parts of the Cell Cycle?

Back 6

Mitosis & Interphase

Front 7

Name the stages of Mitosis

Back 7

Prophase, Metaphase, Anaphase, Telophase

Front 8

By what process does the cell eventually ‘pinch’ into two?

Back 8

Cytokinesis

Front 9

Roughly how long does Mitosis last for?

Back 9

1 hour

Front 10

Name the phases of Interphase

Back 10

G1, S, G2

Front 11

What processes occur in G1?

Back 11

Activation of transcription factors, duplication of some organelles, growth in size/mass

Front 12

Where are the checkpoints in G1 and what are they for?

Back 12

Towards the end (Restriction checkpoint for G0) checks for adequate cell size and favourable external environment, At the end – checks for errors in DNA & destroys cells by action of Tumor Suppressor Genes (TSGs) if errors are found

Front 13

What happens in G0?

Back 13

Cell is quiescent, but still performing its normal activities. It is outwith the normal cell cycle and may require an external stimulus to re-enter

Front 14

What allows the progression from G1 → S phase?

Back 14

Cyclins bind to Cyclin Dependent Kinases(CDKs) which phosphorylate the Retinoblastoma (Rb) complex. This allows the release of Transcription Factors and allows the cell to progress onto DNA replication (S phase)

Front 15

What happens in S phase?

Back 15

Duplication of Chromosomes into 2 Chromatids, connected at their kinetochores by a centromere

Front 16

What happens in G2 phase?

Back 16

Further cell growth and replication of remaining organelles

Front 17

What allows the progression from G2 → M phase?

Back 17

Accumulation of Mitosis Promoting Factor (MPF), which is a Cyclin CDK complex, as well as passing of G2 checkpoint

Front 18

What does the G2 checkpoint do?

Back 18

Regulates entry into Mitosis. Checks for correct duplication of chromosomes and centrosomes. Incorrect duplication results in the promotion of apoptosis by TSGs

Front 19

Generally, what controls the cell cycle?

Back 19

Phosphorylation reactions performed by CDKs

Front 20

What does the Metaphase checkpoint do?

Back 20

Checks for complete spindle attachment and alignment at the metaphase plate. Controls entry into anaphase.

Front 21

What goes wrong in the cell cycle to cause cancer?

Back 21

Many different factors that can allow mutated cells to progress through the cell cycle and reproduce

Front 22

Name the two most common types of mutation to cause cancer

Back 22

Non-responsiveness to external growth inhibitory stimuli. Mutation that causes the need for external stimuli to become nullified.

Front 23

Name 4 less common effects of mutation causing cancer

Back 23

Promotion of Angiogenesis. Evasion of apoptotic pathway by alteration of said pathway. Activation of telomerase enzyme to produce immortal cell line.

Front 24

The production of what type of gene causes carcinogenic mutations?

Back 24

Oncogenes

Front 25

What two effects can oncogenes have on proteins?

Back 25

Overactive/Inactive protein product. Normal products but: wrong cell type, wrong time or wrong quantity

Front 26

What will be the effect of inactive p53 protein?

Back 26

Failure to regulate cell cycle by halting activation of CDK complexes.

Front 27

How many mutations are normally required to cause a cancer?

Back 27

5-8

Front 28

What do TSG’s proteins do?

Back 28

Regulation of cell cycle, promotion of apoptosis, or both

Front 29

How does p53 work?

Back 29

Low conc. Switches on p21 which inhibits CDK molecules, hence inhibiting cell cycle progression. High conc. Switches on pro-apoptotic genes

Front 30

What is an example of an overactive protein product due to mutation?

Back 30

Small G-protein ras: overactivity causing lack of inhibition in cell cycle progression