10.6 Control of the cell cycle

Question 1

2 concepts to control cell cycle

Answer 1

1. cell cycle has two irreversible points

2. cell cycle can be put on hold at checkpoints

Question 2

Irreversible points of cell cycle

Answer 2

• replication of genetic material

- separation of sister chromatids

Question 3

checkpoints

Answer 3

• checks to make sure functioning normally
• can be stopped if errors
• allows cell to respond to internal and external signals

Question 4

G1/S checkpoint

Answer 4

• cell decides whether or not to divide

- if cell is going to grow, repair, reproduce and meets checkpoints it can continue through cycle

Question 5

G2/M checkpoint

Answer 5

• cell makes commitment to mitosis
• can stall cycle if DNA has not been replicated
• checks to make sure DNA was copied correctly
• DNA can be fixed before going to metaphase

Question 6

Late metaphase (spindle) checkpoint

Answer 6

• cell ensures all chromosomes are attached to spindle fibers in order to pull them apart
• before cytokinesis

Question 7

When does cancer occur?

Answer 7

• uncontrolled growth of cells

- failure of checkpoints

Question 8

Two types of genes can disturb cell cycle when they are mutated

Answer 8

1. tumor-suppressor genes

2. proto-oncogenes

Question 9

tumor-suppressor genes

Answer 9

• p53 in G1 makes sure there is no damage in DNA in order to divide
• prevents development of mutated cells
• normal p53 proteins destroy irreparable damage to DNA
• abnormal p53 fails to stop cell division, cancer develops
• apoptosis present kills damaged DNA cells

Question 10

Proto-oncogenes

Answer 10

• normal cellular genes that become oncogenes when mutated
• tells cell when it can grow and divide
• if proto-oncogenes are mutated cell will grow faster

Question 11

Cancer develops when what is not present?

Answer 11

1. tumor- suppressor genes

2. proto-oncogenes

Question 11

A growth factor released by clotting blood

Answer 11

-PDGF

Question 12

M phase-promoting factor

Answer 12

• composed of cyclin & kinase

- acts as positive regulator of cell cycle progression in frogs

Question 13

Cyclins

Answer 13

• regulatory proteins

- required to activate Cdks

Question 14

Anaphase promoting complex

Answer 14

-marks securin protein for degradation by proteosome

Question 15

Oncogenes

Answer 15

-genes that when introduced into cell cause it to become cancer cell

Question 16

Growth factors tumor suppressors

Answer 16

• trigger intracellular signaling system

- can override cellular controls that inhibit cell division

Question 17

Proto-oncogenes

Answer 17

• mutations in these genes have dominant

- gain of function leads to cancer