Cell Biology - Outcome 4

Question 1

what two processes must a cell undergo to grow and divide?

Answer 1

• replication: doubling of chromosome complement to create 2 copies of each piece of DNA
• mitosis: nuclear division that results in each daughter cell receiving full chromosome complement

Question 2

what are the phases of the cell cycle?

Answer 2

• G1
• S
  -G2
• M

Question 3

what phases are known as interphase?

Answer 3

• G1
• S
• G2

Question 4

what do the phases of the cell cycle depend one to move from one phase to the next?

Answer 4

cyclin-dependent kinases (CDKs)

Question 5

what do CDKs do?

Answer 5

activate other proteins by adding phosphate groups (phosphorylation)

Question 6

how do CDKs become active?

Answer 6

they must bind to cyclins

Question 7

what happens in the G1 phase?

Answer 7

• as level of cyclin increases, it increasingly binds to CDK
• signals cell to prepare for chromosomes for replication
• cell will be growing

Question 8

what happens during G0 phase?

Answer 8

• resting stage (temp or perm)
• not actively growing and dividing but they are often still highly metabolically active carrying out cellular functions
• phase is brought about by absence of cues for growth and division - genes controlling mitosis are actually repressed

Question 9

which cells temporarily enter G0?

Answer 9

• lymphocytes which remain in that phase until they encounter an antigen
• when they do - they re-enter G1, becoming self-replicating colonies