Tumour Pathology 4 Flashcards Preview

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Flashcards in Tumour Pathology 4 Deck (61)
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1

What is mitosis?

Mechanism of cellular replication

2

What does mitotic division generate?

Two genetically identical daughter cells

3

What is a cell cycle?

Time interval between miotic division

4

What is the cell cycle made up of?

G0

G1

S

G2

M

5

What happens during G0?

Left cell cycle and stopped dividing

6

What happens during G1?

Synthesis of components needed for DNA synthesis

7

What happens during S?

DNA synthesis

8

What happens during G2?

Preparation for mitosis

9

What happens during M?

Mitosis and cell division

10

How much cell divisions occur per second in humans?

25 x 106

11

How many cells are in the body?

1013

12

What does quality control insure?

Genetic fidelity:

 

Each cell must recieve a full chromosome compliment

Mutations in DNA sequences must not pass on

13

What factors is the cell cycle control by?

External factors

Intrinsic factors

14

What external factors control the cell cycle?

Hormones

Growth factors

Cytokines

Stroma

15

What intrinsic factor controls the cell cycle?

Critical checkpoints (restriction point R)

16

What does progress before and after restriction point R depend on?

Prior depends on external factors

After becomes autonomous

17

Where is R?

At the end of G1

18

What does G1 control mechanism ensure?

Everything is ready for DNA synthesis

19

What does G2 control mechanism ensure?

Everything is ready for cell division

20

What do checkpoints in G1 check?

Cell size is inadequete

Nutrition supply inadequete

Essential external stimulus lacking

DNA damage detected

21

What do checkpoints in S check?

DNA is not replicated

Chromosome mis-alignment

22

What do checkpoints in G2 do?

Cell size is inadequete

DNA damage is detected

23

What are checkpoints?

Systems of cyclically active and inactive enzymes

24

What is a catalytic subunit activated by?

Regulatory subunit

25

What are cyclin dependant kinases (CDK)?

Catalytic subunits

26

What are the catalytic subunits?

Cyclin-dependent kinases (CDK)

27

What are cyclines?

Regulatory subunits

28

What are the active enzyme component of checkpoints called?

CDK/cyclin complex

29

What is the process of cyclines and cyclin dependant kinases?

1) Different CDKs and cyclines operate at sequential stages of the cycle

2) Active CDK/cyclin complex phosphorylates target proteins

3) Phosphorylation results in activation/inactivation

4) Substrates regulate events in the next cycle phase

30

How are CDKs regulated?

CDKs are constitutively expressed in an inactive form, whereas cyclines accumulate and are destroyed as cycle progresses

CDKs inhibitors (CKIs)