CMB1004/L05 Cell Cycle Flashcards
What are the products of meiosis?
4 genetically different haploid daughter cells
What are the products of mitosis?
2 genetically identical diploid daughter cells
In prokaryotes, what are the 2 phases of binary fission?
Replication & Division
In eukaryotes, what are the 4 phases of mitosis?
Mitosis & Cytokinesis
Synthesis
Gap phase
Interphase
Give the 6 stages of M phase.
Prophase
Prometaphase
Metaphase
Anaphase
Telophase
Cytokinesis
What occurs during Prophase in mitosis? (2)
Mitotic spindle replicated and moved apart
Condensing and replication of chromosomes
What occurs during Prometaphase in mitosis? (2)
Nuclear envelope breaks down
Centrosomes at spindle pole and begin to bond to chromosomes
What occurs during Metaphase in mitosis? (2)
Sister chromatids align at spindle equator
Microtubules pull DNA to opposite poles of cell
What occurs during Anaphase in mitosis?
Sister chromatids pulled apart to form daughter chromosomes, separated and pulled to opposite poles of the cell
What occurs during Telophase in mitosis? (3)
Contractile ring contracts
Nuclear envelope begins to form
Daughter chromosomes decondense
What occurs during Cytokinesis in mitosis? (4)
Contractile ring creates cleavage furrow
Nuclear envelopes complete
Actin & myosin pinch membrane
Reformation of interphase microtubules
What occurs during interphase? (3)
Cell growth
Gene transcription
Protein synthesis
What occurs during G1? (1)
Main growth
Checkpoint
What occurs during S phase?
DNA synthesis
What occurs during G2? (1)
Growth and final preparation
Checkpoint
Name the 3 checkpoints of mitosis.
G1, G2 & M
What internal factor regulates checkpoints in mitosis?
Growth factors (GFs)
What external factors regulate checkpoints in mitosis? (2)
Density-dependent inhibition
Anchorage replication
What are checkpoints in mitosis controlled by?
Cyclin-dependent kinases (Cdk)
What signals that a cell is ready to proceed to the next phase in mitosis?
Phosphorylation
What is quiescence?
Absence of proliferation signals in cells
What occurs in mammalian cells with no signals? (2)
Enter G0
Apoptosis
What occurs during G0?
Maintenance only
What causes the most variation in frequency of cell division?
Time in G0/G1
Give 2 examples of growth factors.
Platelet-derived growth factor
Fibroblast growth factor
Epidermal growth factor
What concentration of growth factor is required for mitosis?
10^-10M
Lack of what molecule causes cells to enter G0?
Growth factor
When is apoptosis triggered? (2)
Physiologic activation
Pathogenic activation
Give 2 examples of physiologic activation of apoptosis.
Embryonic development
Removal/remodelling of tissues
Maintenance of homeostasis
Control cell numbers
Give 2 examples of pathogenic activation of apoptosis.
Viral infection
Heat shock/toxins
Removal of stressed/damaged cells
What kind of signals can activate apoptosis? (2)
Hormonal signals
Direct signals from contacting cells
What 2 things can suppress apoptosis?
Survival factors
Contact with extracellular matrix
What is gene p53?
Transcription factor that increases apoptosis genes
What 3 key events occur during apoptosis?
Activation of gene p53
Mitochondria become leaky and release cytochrome C
Activation of caspases
What causes gene p53 to activate?
DNA damage
Which checkpoint do cells with activated p53 become blocked at?
G1
What does the caspase cascade lead to? (2)
Activation of Dnase
Cleavage of lamins and cytoskeleton
What 3 functions do caspases have?
Cleaving of nuclear lamins
Activation of DNase
Cleave cytoskeleton
What is necrosis?
Accidental cell death due to injury
What occurs during necrosis? (3)
Nuclear swelling
Cell membrane becomes leaky
Lysis & cell contents released
What bodily response is caused by necrosis?
Inflammation
