cytokinesis

Question 1

review: western yew tree, what is it, what is it used for

Answer 1

taxol! derived from the tree and is an inhibitor of cell proliferation by binding MTs so that they are stabalized so that they do not depolymerize

Question 2

review: saffron, what does it make, what is it used for

Answer 2

colchicine! derived from the saffron to treat gout (uric acid) it binds to tubulin subunits and prevents their polymerization into MTs. May inhibit cell migration of neutrophils to the site of inflammation

Question 3

what executes cytokinesis? organization?

Answer 3

actin and myosin; contractile ring is built from actin and myosin to pinch off the cell membrane

Question 4

mitotic cyclin disappears when? important in?

Answer 4

disappears between anaphase and telophase; important in activating early mitotic events

Question 5

what kinds of regulators work to drive the cell cycle?

Answer 5

protein kinases and protein phoshatases that drive the cell cycle. there are also inhibitors

Question 6

SMADS control? if bad what happens?

Answer 6

the transcription of the small inhibitors that regulate the cell cycle; if bad, the cell keeps proliferating because it doesn’t turn off.

Question 7

contractile ring location

Answer 7

typically arises at the cortical cytoplasm where the chromosomes were lined up.

Question 8

how is contractile ring built?

Answer 8

the cell has to decide where to put the ring, then it brings the machinery to that site. it pinches and the midbody has to do something

Question 9

what is the scientific research methodology used to study the actin and myosin contractile ring?

Answer 9

show the protein is there, use genetic studies to find the characteristics, take away elements and see what happens

Question 10

whats cool about cellular slime mold?

Answer 10

its a community of cells; it has signal transduction, it is polarized, it locomotes as a multicellular slug, it comes together to make more slugs

Question 11

immunocytochemistry needs?

Answer 11

specific antibodies; a dead, sliced cell to see a cell at ONE point of time

Question 12

green fluorescence protein is good because?

Answer 12

you can take the fluroescence of the natural compound to study a LIVE cell so that you don’t have to kill a cell to study it; it requires NO COFACTORS; it makes a fluorescent center of 3 aa. in the middle of the barrel; it also comes in a multitude of colors

Question 13

GFP used in what studies?

Answer 13

protein lifespans, gene expression by promotor-reporter fusions, protein protein interactions

Question 14

what are the three amino acids in the GFP marker?

Answer 14

ser-tyr-gly

Question 15

where does actin accumulate in a dividing cell?

Answer 15

“cortical site” of the contractile ring

Question 16

localization doesn’t mean?

Answer 16

localization doesn’t mean that it is doing something there!!

Question 17

myosin II knock out proves?

Answer 17

you need this to divide the cell!! when it lacks, you make daughter nuclei that are still living in the same cytoplasm because the cell couldn’t make a contractile ring. this is ultimately fatal to the cell

Question 18

if you put myosin II knock out on a plate, what happens?

Answer 18

it survives because the daughter cells can crawl away and they essentially tear off the original cell. this is called “traction-mediated cytofission”

Question 19

how does phalloidin relate to cell division?

Answer 19

it binds to filamentous actin and stabalizes it so that it cannot cytokinese because it cannot either form or pinch

Question 20

remember, what can you use small molecule inhibitors for?

Answer 20

anticancer agents, fungicides, herbicides

Question 21

Blebbistatin general function?

Answer 21

inhibits blebbies. (cell surface protrusion) blebbies suuper abundant in apoptosis. its a myosin II inhibitor (muscle myosin) it does NOT inhibit myosin I, V etc

Question 22

Blebbistatin blocks what action? it is used to prove what?

Answer 22

the power stroke of myosin; this proves that actin and myosin are both active in the constriction of the contractile ring. the sister chromatids will separate, but the cell will not cytokinese

Question 23

purse-string model? the end all model?

Answer 23

at anaphase and telophase, the actin and myosin arrange in a donut, and it pinches together; no. there are other ways to get the cell to pinch as well.

Question 24

how does the actin and myosin know where to accumulate in a dividing cell?

Answer 24

too much for this card. keep going

Question 25

rappaport, and sanddollar cell. what does it prove?

Answer 25

he put a glass bead in the middle of the cell to make it a donut but the cell doesn’t care. it divides into a horseshoe, and then divides with an EXTRA contractile ring. the ASTRAL MTs dictate the cytokinesis site

Question 26

What happened when Mr. Dong Zhang took the nucleus out of a dividing cell? what does it prove?

Answer 26

without the astral mts, it STILL cleaves. this model says the interpolar MTs decide.

Question 27

overall, what is our main take away for the location of contractile ring?

Answer 27

there are multiple mechanisms that specifiy the plane of division in a cell that needs to cytokinese

Question 28

players that are specified to go to the contractile ring? What is the major signalling molecule?

Answer 28

hundreds of proteins. Just remember that we have some VIPS like the monomer binders, the things that nucleate filaments, the motor proteins. Gproteins regulate!!!

Question 29

what kinds of things are G proteins involved in

Answer 29

they are upstring for Ras, Rho,

Question 30

rho rho rho your boat leads to?

Answer 30

actin ring formation by controlling actin polymerization and the polyermization of myosin that leads to the GTP loaded structure that is ready to go

Question 31

what did he encourage us to study before the shelf?

Answer 31

turek’s notes. ew.

Question 32

what if you don’t want to look at turek’s notes?

Answer 32

check out apoptosis in some sort of BRS book because that material will be on both histology and molecular