What are key events in meiosis 1
- synapses of homologous chromosomes
- crossing over (exchange of genetic material between nonsiter chromatids)
- homologous chromosomes separate
Key event in meiosis 2
- separation /segregation of sister chromatids
- generation of 4 haploid gametes all different
what are key events present only in meiosis
- synapsis and crossing over
- tetrads on the metaphase plate
- separation of homologous chromosomes
what is checkpoint #1 in cell division?
- all the nucelotides
- DNA replication enzymes
- sufficient nutrients and 02
Checkpoint #2 in cell division
all DNA replicated
checkpoint #3 in cell division
-has the cell reproduced its organelles and other structures needed to produce 2 cells identical to a parent cell or 4 gamets
proteins that are needed for mitosis
structural proteins such as tubulin for microtubules and other proteins for carrying out processes
what are cell cycle control molecules
kinases- enzymes that activate or inactive orhter proteins by phosphorlyating them. i.e by putting phosphate on proteins
What forms MPF
cyclin B
cyclin department kinase 2 cdk2
what is MPF
M-phase promoting factor
maturation promoting factor
mitosis promoting factor
its made of 2 proteins-cdk2 cyclin B
When is MPF inactivated
when cyclin is degraded
When is MPF functional
functional during : metaphase, anaphae
not functional during : telophase
What is APC
anaphase-promoting complex
-stimulates the degradation of a protein called securin by tagging it for degradation in the proteosome
What is separase
loss of securin releases a proteases
Why does separase degrade cohesins
allow for sister chromatids separation during anaphase
APC also puts a tag on what and targets for what
tag on cyclin target cyclin for degradation
What happens if MPFs gone
chromosomes decondense,
nuclear envelope forms and the spindle disassembles.
