cytoplasmic division following nuclear division, resulting in two new daughter cells.
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interphase
phase of the cell cycle where the cell is not dividing; it is subdivided into growth and synthesis phases.
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mitosis
type of nuclear division that produces daughter cells genetically identical to each other and to the parent cell.
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interphase appears to be uneventful, but what do we know to go against this?
during interphase, there are elaborate preperations being made for cell division in a carefully ordered and controlled sequence, with checkpoints.
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what are the 2 main checkpoints in the cell cycle?
G1/S checkpoint (restriction point) and the G2/M checkpoint.
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what is the purpose of the checkpoint?
to prevent uncontrllable division that would lead to tumours and to detect/repair any damaged DNA.
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why do the molecular events controlling the cell cycle happen in a particular sequence?
so that the cycle cannot be reversed and the DNA only gets duplicated once during the cycle.
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M phase - a checkpoint chemical triggers condensation of chromatin.
cell growth stops; mitosis occurs; cytokinesis.
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metaphase checkpoint.
Halfway through the cycle, the metaphase checkpoint ensures that the cell is ready to complete mitosis.
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G0 (gap 0) phase - a resting phase triggered during early G1 at the resting point, by a checkpoint chemical.
cells may undergo apoptosis (programmed cell death), differentiation or subscence. some cells remain in this stage indefinitely like neurones.
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G1 (gap 1) phase - (growth phase) A G1 checkpoint control mechanism ensures that the cell is ready to enter the S phase and begin DNA synthesis.
cells grow/ increase in size; transcription of genes making RNA occurs; organelles duplicate; biosynthesis; the p53 gene helps control this stage.
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S (synthesis) phase - because the chromosomes are unwound and the DNA is diffuse, every molecule of DNA is replicated in a specific sequence.
must complete the cell cycle; DNA replicates; when all chromosomes have been duplicated, each one consists of a pair of sister chromatids; fast.
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G2 (gap 2) phase - special chemicals ensure the cell is ready for mitosis by stimulating proteins that will be involved in making chromosomes condense and in formation of the spindle.
cells grow.
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recap cell stages
G0 - may undergo apoptosis, differentiation or senescence . some stay indefinitely.
S (synthesis) phase of interphase - DNA replicates; chromosomes duplicate;
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recap cell stages
G2 interphase - cells grow
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recap cell stages
M phase (mitosis) - nuclear division with stages prophase, metaphase, anaphase and telophase
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recap cell stages
cytokinesis - cell splits in two
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what is apoptosis?
programmed cell death. cells can only replicate a certain aount of times - the Hayflick constant = cells should undergo 50 mitotic divisons before apoptosis.
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how is the cell cycle regulated?
p53 gene - triggers the checkpoints. Proto-oncogenes - regulates cell divison by coding for proteins which help to regulate cell growth and differentiation. Cyclins - proteins produced as a response to cell signalling.
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how do prokaryotic organisms divide?
binary fission
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how many chromosomes does a human have?
46
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chromatin
DNA + histones (ball shaped proteins which DNA strands wrap around) = chromatin
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Other cards in this set
Card 2
Front
phase of the cell cycle where the cell is not dividing; it is subdivided into growth and synthesis phases.
Back
interphase
Card 3
Front
type of nuclear division that produces daughter cells genetically identical to each other and to the parent cell.
Back
Card 4
Front
during interphase, there are elaborate preperations being made for cell division in a carefully ordered and controlled sequence, with checkpoints.
Back
Card 5
Front
G1/S checkpoint (restriction point) and the G2/M checkpoint.
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