2.6.1 The Cell Cycle

Question 1

Phases of cell cycle

Answer 1

• Interphase
• Mitosis
• Cell division (cytokinesis)

Question 2

What are cyclins?

Answer 2

• Trigger one phase to move to another in the cell cycle

Question 3

What is interphase?

Answer 3

• Cell increases in mass and size whilst carrying out its normal cellular functions
• Consists of G1 phase, S phase and G2 phase

Question 4

What is the G1 phase

Answer 4

• Cell contents excluding chromosomes are duplicated
• Cell carrying out its function

Question 5

What is the S phase

Answer 5

Each of the 46 chromosomes are duplicated by DNA replication

Question 6

What is the G2 phase

Answer 6

• Cell ‘double checks’ for errors in DNA replication
• Tubulin is produced for microtubules for spindle fibres for cell division (cytokinesis)

Question 7

What is the G0 phase

Answer 7

• ‘Dormant’ state
• Cell leaving cell cycle
• No growth factors, DNA damage, other environmental factors could cause this

Question 8

What happens during M phase

Answer 8

• After interphase
• Mitosis occurs
• Cell growth stops

Question 9

What is cytokinesis?

Answer 9

• Follows M phase
• Once nucleus divided into 2 genetically identical nuclei
• Whole cell divides into 2 genetically identical daughter cells

Question 10

What regulations occur in each phase of the cell cycle?

Answer 10

G1 - Chromosomes checked for damage, does not advance to S phase until repaired

S - Chromosomes checked to see if they have been fully replicated. If not, cell cycle stops

G2 - Same as G1

DURING METAPHASE - Final check to see if chromosomes are correctly attached to spindle fibres prior to anaphase