L23 Cell Cycle

Question 1

Stem cells

Answer 1

Toti > Pluri > Multi

Question 2

Cell regeneration

Answer 2

Some cells regenerate e.g. liver regeneration, there is control of organ size - the liver cells doesn’t just keep on regenerating

Question 3

Cell division

Answer 3

IPMAT

gene activity e.g. cell transcription during interphase

little gene activity during metaphase

Question 4

Yeast

Answer 4

Budding

Binary fission

Question 5

Cell cycle

Answer 5

see onenote

G1>s>G2>M

Cell growth mainly occurs in G1 and G2 or both
OR
Virtually no G1 or G2 => cell division without growth

Question 6

Cell growth signalling

Answer 6

see one note

growth factor => cell growth
mitogen => mitosis

Question 7

Different cell types

Answer 7

Some cells have no nuclei e.g. RBC

Some cells have multiple gene copies e.g. Drosophila salivary glands has polytene chromosomes, no mitosis/cytokinesis

Some cells have multiple nuclei e.g. multinucleate hyphae

Question 8

Growth gives shape

Answer 8

see onenote

• Growth in both polar ends => disc-like shape
• Growth in one end, polarised - hyphal growth

Question 9

Cell cycle variation

Answer 9

see onenote

• normal
• rapid
• no cytokinesis/mitosis

Question 10

Amphibians cell cycle

Answer 10

see onenote

virtually no G1 or G2, no increase in size
cell division without growth

Question 11

Drosophila cell cycle

Answer 11

see onenote

• Nuclear division without cell division in the early stages of development => Many nuclei in a syncytium => nuclei migrate to the periphery => cellularization

Question 12

Cell programming

Answer 12

Programmed cell death - apoptosis

• Response to cell damage e.g. heat shock, irradiation
• Normal development e.g. formation of digits

Question 13

Cell fate in C.elegans

Answer 13

• Every cell lineage determined

- Discovery of apoptosis, some of the lineages end up in death

Question 14

Progression through cell cycle is controlled

Answer 14

see onenote

• Mitotic check point e.g. is the environment favourable, is everything okay for mitosis to proceed

Question 15

Cyclins

Answer 15

see onenote

• Cyclinis a family of proteins that control the progression of cells through the cell cycle by activatingcyclin-dependent kinase (Cdk) enzymes.
• Combination of cyclin and CDK is key to controlling the cell cycle
• Cyclins are degraded but the CDKs are present all the time
• Control dependent on protein levels, level of cyclin