lec 2. mitosis

Question 1

cell-free mitosis

Answer 1

Deplete cytoplasm from egg and mix with nuclei from sperm and study what happens. Can also remove cytoplasms at different stages to study changes.

Question 2

phases of mitosis

Answer 2

prophase - condensation of sister chromatids
metaphase - mitotic spindle attaches to kinetochore
anaphase - separation of sister chromatids
telophase - nuclear envelope reassembly, start of cytokinesis

Question 3

model systems used in mitosis

Answer 3

fission/budding yeast

xenopus

Question 4

how M-Cdk triggers mitosis

Answer 4

Cdk-activating kinase (CAK) and Cdk-inhibting kinase (WEE1) phosporylate M-cdk.
In late G2, Cdc25 removes inhibitory phosphate
M-cdk becomes active

Question 5

what does M-Cdk trigger

Answer 5

assembly of mitotic spindle
chromosome condensation
breakdown of nuclear envelope

Question 6

how APC regulates entry into anaphase

Answer 6

it is a ubiquitin ligase which breaks down Securin (allows sister chromatids to separate) and breaks down cyclin B

Question 7

loss of heterozygosity

Answer 7

the loss of one parents contribution to the cell through nondisjunction, mitotic recombination, an gene conversion

Question 8

hemizygosity

Answer 8

loss of one parents copy in a region of a gene

Question 9

astral microtubule

Answer 9

contact cell cortex (actin cortex) to position the spindle

Question 10

kinetochore microtubule

Answer 10

attach to chromosome at the kinetochore

Question 11

interpolar microtubule

Answer 11

overlap

Question 12

ways to get loss of heterozygosity

Answer 12

direct deletion, deletion due to unbalanced rearrangements, gene conversion, mitotic recombination, loss of chromosome