cell cycle 3rd oct Flashcards
What are the 5 stages of cell cycle?
- G0 phase
- Gap 1
- (S)ynthesis phase
- Gap 2
- Mitosis
What happens during the G1 phase?
Growth of cell
cellular contents are duplicated
preparation for DNA synthesis
What happens during S phase?
DNA replication of each of the 23 pairs
What happens during G2 phase?
Preparation for Mitosis
More cell growth
What are the 5 phases of mitosis?
Prophase
Metaphase
Anaphase
Telophase
What happens during prophase?
DNA material (chromatin) condensed into chromosomes
Cell growth
Mitotic spindle fibres begin to form
What happens during proMETAphase?
Nuclear envelope dissolves allowing for spindle fibres to attach
What happens during metaphase?
Chromosomes line up along the metaphase plate
Spindle fibres attach at their centromere
What happens during Anaphase?
Spindle fibres contract
Sister chromatids dragged apart toward the polar ends
Cell begins to elongate for cellular division
What happens during Telophase?
cell dimples
nuclear envelope begins to reform
Spindle fibres break down
What happens during Cytokinesis?
Cytoplasm divides- actin ring pinches cytoplasm along the crease of the two new cells- cleavage furrow.
two new cell forms
Why isn’t cytokinesis considered its own phase?
Stage begins between anaphase and telophase but doesn’t finish until telophase is over.
What are the 3 major checkpoints of cell cycle?
G1/S phase checkpoint
G2/Mitosis checkpoint
Spindle checkpoint
What does the G1/S phase checkpoint do?
this checkpoint makes sure that the cell is committed to cell proliferation.
what does the G2/M checkpoint do?
Has the dna synthesis been completed correctly?
Commitment to mitosis
What does the spindle checkpoint do?
are all chromosomes attached to spindles
Can sister chromatids separate correctly
What is DNA DAMAGE RESPONSE?
it detects DNA lesions, signals their presence and promotes their repair.
What is meant by replication stress?
this is the trancient slowing or stalling of replication forl
What is progression through the cell cycle primarily controlled by?
Proteins in the cytoplasm- Cyclins and Cyclin dependant kinases.
when cyclins are bound to Cyclin dependant Kinases what happens?
cell cycle is driven forward.
What is chromosome segregation?
process by which 2 sister chromatids are separated from each other.
how do cyclins and cdk’s advance cell cycle
- CDKs bind to cyclins
- Cyclin/CDK complex is phosphorylated by a kinase (phosphate donating protein)
- The activated Cyclin/CDK complex acts as a kinase and phosphorylates the target protein.
- the activated protein advances the cell cycle
What are the major types of DNA damage and their repair pathways?
Single strand breaks—Base Excision Repair
Double strand breaks— Homologous Recombination Repair & Non- Homologous End Joining
Nucleotide mutations/substitutions/ deletions/insertions— MisMatch Repair
Bulky Adducts (parts of the DNA chain that bind to cancer-causing chemicals)— Nucleotide Excision Repair.
What happens when a cell senses DNA damage?
