actin inhibiting agents

Question 1

phalloiden

produced by? function?

Answer 1

death cap mushrooms; poisons by stabalizing actin filaments and keeping them from disassemblig

Question 2

cytochalasin

function?

Answer 2

binds actin filaments at the barbed ends; remember thats the (+) end

Question 3

macrolides

made by? bind?

Answer 3

marine sponges; bind actin filaments

Question 4

what is a job you should never pick up?

Answer 4

mushroom hunting; unless you are starving. in that case I’ll allow it.

Question 5

how long does mitosis typically take?

Answer 5

the WHOLE cell cycle of a mammalian cell is about 1 day. MITOSIS usually takes about an hour. but it DEPENDs on the cell type

Question 6

what key concept of S phase should you remember?

Answer 6

there is a cdk (cyclin dependant protein kinase) that allows spindle formation, nuclear envelope to break down. Mr. Cdk is regulated by cyclins. he needs cyclins

Question 7

what state is a cdk in when it is active

Answer 7

DEphosphorylated. also, attached to a cyclin. therefore, phosphatase activity is critical

Question 8

microtubules
polymer or monomer?
subunits?
filament name?
how many filaments in backbone?

Answer 8

polymer; alpha/beta–beta binds GTP; these subunits connect in head to tail fashion and make protofilaments; usually 13 protofilaments in one filament backbone

Question 9

uses of microtubules?

Answer 9

tracks for organizing the cell because they have a distinct polarity. used in motility, transportation, chromosome separation

Question 10

arrangement of microtubules

Answer 10

9+2; use DYENEIN

Question 11

microtubule turnover?

Answer 11

add at (+) end, lose at (-) end, but actually this probably doesn’t happen in cells

Question 12

stability of microbule?

Answer 12

DYNAMIC INSTABILITY; it can grow then all of a sudden fall apart really quickly and then start regrowing again; each polymer grows or falls apart at its own rate; this is like little kids with blocks; be able to contrast this with treadmilling;

Question 13

cap of microtubulin?

Answer 13

GTP cap

Question 14

centrosome definition?

Answer 14

it controls nucleation, where MTs form, how many MTs there are, determines the polarity of a MT; (-) end of MT anchors at the centrosome

Question 15

taxol

binds what? stabalizes? derived from? used for?

Answer 15

microtubules; stablizes or blocks MTs and keeps cells from dividing (antimitotic); from the pacific yew tree; used as an anticancer drug. probably the frontline drug for SOLID tumors (ovarian, breast, lung, bladder, prostate)

Question 16

where does taxol bind?

Answer 16

GTP cap to stabalize it, and blocks transition from GTP to GDP loaded

Question 17

control point of MT?

Answer 17

its easy to elongate a MT, but hard to start one. so, the seed formation is the limiting factor

Question 18

how could you make MTs form more quickly?

Answer 18

add gamma tubulin in the presence of tubulin heterodimers.

Question 19

compare nucleators in actin vs MT

Answer 19

actin: arp2/3 complex and formin
MT: gamma tubulin

Question 20

where does gamma tubulin bind?

Answer 20

at the minus end. that makes sense because its a nucleator.

Question 21

what does gamma tubulin DO to start a MT

Answer 21

associates with gamma TuRC in a “lock washer” configuration; typically there are 13 gamma tubulins that correspond to 13 things. i missed it

Question 22

what is a MTOC

Answer 22

a centrOSOME

Question 23

where are centrIOLES

Answer 23

in the centrOSOME, (at the bottom of an axon, or in a basal body, or in a spindle pole)

Question 24

what is the structure of the centrIOLE

Answer 24

they are 9+THREEEE!!! (the other one is 9+2); it has gamma tubulin and gamma TURK thing

Question 25

what is PCM

Answer 25

paracentriolar fuzz

Question 26

where is centrOSOME

Answer 26

at spindle poles of mitotic spindle apparatus

Question 27

again, what end is at the centrOSOME

Answer 27

the MINUS!!!!

Question 28

at s to G2 transition what happens to centRIOLES

Answer 28

duplicates and separates (2 to 4). the paracentriolar fuzz does the same. one pole becomes the “north pole” the other becomes the “south pole”

Question 29

centrOSOME cycle

Answer 29

in addition to the anaphase, telophase, etc cell cycle

Question 30

what do yo uneed to build a spindle?

Answer 30

microtubules, spindle poles(centrosomes), microtubule motors, chromosomal attachment sites

Question 31

name the 3 pieces/parts of the spindle apparatus

Answer 31

ASTRAL MTS: make contact with the periphery of the cell ** important for position
INTERPOLAR MTS: these cross in the middle in antipolar way. stabalize the distance between centrosomes
KINETOCHORE MTS: these meet in the middle with motors

Question 32

what word should you be able to spell

Answer 32

kinetochore

Question 33

what are the two motor types for microtubules?

Answer 33

kinesin; dynein

Question 34

what directon does a dynein motor crawl?

Answer 34

dynein is dying, he is pessimistic. he goes to the negative end

Question 35

what direction does a kinesin motor crawl?

Answer 35

conventionally, they go +. BUT really they swing both ways. if the motor is at the C-terminus, then it goes toward the negative end. if the motor is in the middle, then they actually aren’t motors, they dissassemble MTS

Question 36

function of kinetochore

Answer 36

captures the chromosome. also, it regulates the behavior of things that you don’t really have to memorize. know that its a multiprotein complex machine

Question 37

after a kinetochore captures a chromosome what happens

Answer 37

there should be a balance of forces between:
plus end binding proteins, plus end polymerizing proteins (CLASPS), and depolymerizing kinesins to drive disassembly of MTS

Question 38

moving to the poles. what are the 3 phases?

Answer 38

anaphase A: you pull the kinetochore MTs apart
anaphase B: you push the centrosomes apart with the overlap MTs and their motors
anaphase C: you pull the centrosomes toward the cell wall with the astral MTs

Question 39

how do you do the metaphase to anaphase transition

Answer 39

use APC (anaphase promoting complex, or cyclosome) it is a ubiquitinizing thing that sends the CDK (remember CDK started this whole ordeal) to a proteasome

Question 40

sister chromatids are held together?

Answer 40

at the equitorial plate in the nucleus by a protein complex called the cohesion complex that is the protein glue that holds them together. they are drawn as loops around the centers of the sister chromatids together.

Question 41

what is separase?

Answer 41

this guy is a protease that targets the cohesin complex that connects sister chromatids and allows them to separate

Question 42

securin?

Answer 42

is the little guy that holds onto separase and keep him inactive until he needs to separate the sister chromatids

Question 43

if you don’t have good metaphase to anaphase transition, what can be a problem?

Answer 43

non-disjunction diseases like trisomy 21 (downsyndrome)