Cell divison
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- Created by: samiyah1234
- Created on: 02-01-21 22:05
What are the stages of mitosis?
Interphase, prophase, prometaphase, metaphase, anaphase, telophase, cytokinesis
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what happens during cytokinesis?
occurs to prepare cell for mitosis:
-cell grows- doubles protein content
-organelles double in size and number
-during s phase dna synthesised
-centrosome replicates
-two gaps: g1 and g2, exist where cell checks everything for next phase
-cell grows- doubles protein content
-organelles double in size and number
-during s phase dna synthesised
-centrosome replicates
-two gaps: g1 and g2, exist where cell checks everything for next phase
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What happens in m phase?
happens in 5 phases:
-prophase, prometaphase, metaphase, anaphase,telophase
-prophase, prometaphase, metaphase, anaphase,telophase
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what happens during prophase?
-chromosomes condense
-mitotic spindle forms
-centrosomes move apart
-protein complex forms at chromosomes
-mitotic spindle forms
-centrosomes move apart
-protein complex forms at chromosomes
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What happens in prometaphase?
-nuclear envelope breaks down- allows microtubules access to chromosomes
-chromosomes attach to microtubules by kinetochore complex
-chromosomes attach to microtubules by kinetochore complex
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What happens during metaphase?
-chromosomes align at equator
-sister chromatids attach to opposite poles by kinetochore complex
-sister chromatids attach to opposite poles by kinetochore complex
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What happens during anaphase?
-cohesive link between sister chromatids is released, kinetochore microtubules shorten.
-centromeres move apart-results in sister chromatids being pulled to opposite poles
-centromeres move apart-results in sister chromatids being pulled to opposite poles
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What happens during telophase?
-daughter chromosomes reach poles
-new nuclear envelope forms from fragments attached to individual chromosomes
-two nuclei contractile rings form around equator
-end of mitosis
-new nuclear envelope forms from fragments attached to individual chromosomes
-two nuclei contractile rings form around equator
-end of mitosis
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What happens during cytokinesis?
-ring contracts partitioning cytoplasm into 2 daughter cells
- each cell contains 1 nucleus, 1 centrosome
- each cell contains 1 nucleus, 1 centrosome
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What does the nuclear lamina needs to do before mitosis?
needs to disassemble
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What is the actin cytoskeleton involved in during mitosis?
in ring contraction during cytokinesis
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What role does microtubules have in mitosis?
kinetochore microtubules attach to chromosomes.
during pMET, microtub grow and shrink
metaphase- motor proteins pull chromo around until aligned
anaphase-kinetochore microtub shorten and motor proteins move chromatids towards centrosome
during pMET, microtub grow and shrink
metaphase- motor proteins pull chromo around until aligned
anaphase-kinetochore microtub shorten and motor proteins move chromatids towards centrosome
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What agents are poisonous and target microtubules?
chemotheraputic agents. They poison microtubules and prevents them from working properly
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What are the 3 checkpoints of a cell to be successfully complete?
-R point-restriction point end of G1
-g2-m transition, checks for environment check size, DNA damage and replication is complete
-meta anaphase transition makes sure all chromosomes attached to spindle-checks if sister chromatid are attached to microtubul
-g2-m transition, checks for environment check size, DNA damage and replication is complete
-meta anaphase transition makes sure all chromosomes attached to spindle-checks if sister chromatid are attached to microtubul
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What are cyclins paired with?
cyclin dependant kinases and these get stronger when a cyclin is attached to it
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What are kinases?
A protein that can attach phosphate groups to other proteins by phosphorylation
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Why are cyclins needed?
to turn on the cyclin dependant kinases
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What does cylin dependant kinases do in the m phase?
regulates g2m transition and meta anaphase transition
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What happens to the cyclin dependant kinases at the end of mitosis?
their activity resets to zero ready to begin again
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What do ubiquitin ligases do in anaphase promoting complex?
targets the mcyclins for degradation
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What do kinases do?
They phosphorylate target proteins
eg. m-cdk phosphorylates
-nuclear lamins to trigger depolymerisation
-microtubule accessory proteins to increase microtubule instability
-chromosomes condensation complex is activated by m-cdk
eg. m-cdk phosphorylates
-nuclear lamins to trigger depolymerisation
-microtubule accessory proteins to increase microtubule instability
-chromosomes condensation complex is activated by m-cdk
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What needs to happen before meiosis?
Mitosis needs to happen as it produces new cells by division of parent cells. The DNA replicates and then the cell divides. This forms 2 identical cells with the same chromosome number as the parent.
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What is the role of meiosis?
cells produced are gamete cells which are required for sexual reproduction
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What type of cells are gametes?
haploid cells
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What type of cells undergo meiosis and divide division to produce gametes?
germ line cells
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What cells in our body divide by mitosis?
somatic cells
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What do gametes require?
one set of chromosomes, so it should be haploid
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What is meiosis important for?
to ensure genetic diversity
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What further increases the possibilities in meosis?
recombination
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What randomly distributes one set of chromosomes to each gamete?
the parents
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How are the cells divided in meiosis?
prophase, prometaphase, anaphase, telophase, cytokinesis all happens twice eg. prophase 1 and prophase 2
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What is prophase split into?
leptotene, zygotene, pachytene, diplotene and diakinesis
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What happens in interphase 1 in meiosis?
there is gap1 synthesis where DNA replicates and gap2. After interphase, the homologues duplicate and so now there are 4 double stranded DNA molecules. The DNA is replicated and forms pairs of chromatids
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What happens in zygotene?
synapsis and this has clusters of proteins which helps the two homologous chromosomes stay together.
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What happens in pachytene?
breakage and invasion of the DNA strands between the maternal and paternal chromosomes-crossing over. This causes recombination to occur. Once crossing over occurs, the synaptonemal complexes that hold strands together are no longer needed
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What happens in the other stages of meiosis?
from metaphase to cytokinesis, it is the same as mitosis but with 23 pairs of chromosomes instead of 46.
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What are the differences in metaphase between mitosis and meiosis?
in mitosis the homologous chromosomes line up at metaphase plate independently but in meiosis they line up in pairs
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What are you left with at the end of meiosis?
4 haploid gametes which are all genetically different from each other
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What happens at anaphase II?
separation of sister chromatids
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What is the same in interphase between mitosis and meiosis?
both have s phase g1 and g2 phase o DNA replicates both at the beginning
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Other cards in this set
Card 2
Front
what happens during cytokinesis?
Back
occurs to prepare cell for mitosis:
-cell grows- doubles protein content
-organelles double in size and number
-during s phase dna synthesised
-centrosome replicates
-two gaps: g1 and g2, exist where cell checks everything for next phase
-cell grows- doubles protein content
-organelles double in size and number
-during s phase dna synthesised
-centrosome replicates
-two gaps: g1 and g2, exist where cell checks everything for next phase
Card 3
Front
What happens in m phase?
Back
Card 4
Front
what happens during prophase?
Back
Card 5
Front
What happens in prometaphase?
Back
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