Lesson 17 - The Cell Cycle Flashcards
1
Q
Two main stages in the cell cycle?
A
- Interphase
- M(mitotic) phase
2
Q
When does the cell carry out the function of the cell type?
A
Interphase
3
Q
3 stages of Intephase
A
- G1 phase
- S (synthesis) phase
- G2 phase
4
Q
G1
A
- Cell growth
- Organelles duplicate
- Transcription occurs
- Biosynthesis occurs
5
Q
S (synthesis phase)
A
- DNA synthesis / replicates (housekeeping genes first, inactive last)
- Chromosomes replicated
- Rapid because exposed base pairs more susceptible to mutagenic agents.
6
Q
G2
A
- Energy stores replaced
- Transcription / translation
- Chromosome repair (if damaged)
- Size of cell increases
7
Q
M (mitotic phase)
A
- Mitosis
- Cytokinesis
8
Q
G0 phase why enter?
A
- Fully differentiated cells
- Senescent cells (when DNA inside cells damaged)
- Cells in G0 temporarily (B memory cells)
9
Q
Checkpoints:
A
- If fails then cell enters G0
3 checkpoints:
G1 checkpoint: Before S phase (grown to the correct size / DNA damage / nutrients)
G2 checkpoint: Before M phase (DNA damage and correct size)
Metaphase / spindle assembly checkpoint: Before cytokinesis (checks that chromosomes are assembled correctly on mitotic spindle)
10
Q
G0
A
- Apoptosis
- Senescence
- Differentiation
- Some cells stay indefinitely
11
Q
G1 / S checkpoint
A
- ‘restriction point’
- Prevents uncontrolled division (lead to tumour growth)
- Cell cycle cannot go backwards.
12
Q
G2 / M checkpoint
A
- Detection and repair of damaged DNA
- Ensures DNA is only replicated once during each cell cycle.
13
Q
Epithelial cells
A
- Lining human intestine
- Remain in G1 for only 2 hours
14
Q
Liver cells
A
- Many months move through G1 to S phase
15
Q
Nerve and muscle cells:
A
- Always in G1 phase
16
Q
Zygote cell division
A
- No G1 and G2 of interphase for first 4 divisions. Only DNA synthesis.
- Enough materials in Zygote to make 16 cells.
- Embryo divides to make smaller cells.
- Faster embryonic cycle enabled.
17
Q
Cancer cell division:
A
