Zara's Content

Question 1

What are the three main functions of the cytoskeleton

Answer 1

1. intracellular organization
2. cell communication
3. cell mobility/morphology

Question 2

what cell junctions connect cytoskelton components in adjacent cells?

Answer 2

adherens junctions and desmosomes

Question 3

High doses of FSH induced changes in the actin cytoskeleton which resulted in the premature converions of granulosa cells to luteal cells. what hormone has an increased concetration?

Answer 3

progesterone

Question 4

Name three attributes of Intermediate Filaments

Answer 4

• they are made up of differnt rtpes of subunits
• they have no nucleotide binding site (no ATP/GTP hydrolysis site)
• they are formed from 2 dimers, this means they have no polarity or directionality

Question 5

Name three attributes of Actin Filaments

Answer 5

• they are found on cell surfaces, shaping the cell and other places
• it has a ATP or ADP bound (ATPase function)
• they form a right handed helix

Question 6

Name three attributes of Microtubules

Answer 6

-they hydrolyse GTP on thier beta tubulin subunits (GTPase)
- they are the stiffest strightest cytoskeletal components and can bear the most force
- they have inherent poalrity due to all subunits being oriented the same way

Question 7

Cumulus cells use bi directional communication via _____ communicate with the oocyte

Answer 7

gap junctions, and oocytes use themn to communicate back

Question 8

High levels of WHAT maintain oocyte arrest?

Answer 8

cAMP

Question 9

What is the function of CapZ

Answer 9

It functions to stablize actin filaments. this prevents rapid depolymerization.

Question 10

How does CapZ work?

Answer 10

it binds to the plus end and reduces the rate of filament growth depolymerization, this leads to stablization. They are present in low concentrations and have major impacts on the entire actin filament network

Question 11

What does cofilin do?

Answer 11

it binds to an actin filament lengthwise, causing it to twist tighter , thus increasing mechanical stress. The result of this is:
- weakened contacts between actin subinits
- increased susceptibility to being severed by thermal motions
- rapid dissasembly
-

Question 12

What are the four types of actin filament arrays?

Answer 12

• contractile bundles
• gel like network
• dendtritic network
• tight parallel bundles

Question 13

Following the LH surge, granulosa cells

Answer 13

-stop replicating
-become hypertrophic
- accumulate lipid droplets (via progesterone)

Question 14

True or False: LH induces changes in steroidgenesis and changes in cell morphology

Answer 14

True

This is due to changes in cAMP/Rhoa pathway. Rhoa activation leads to actin turining into stress fibers.

Question 15

Is cofilin INHIBITED or ACTIVATED by LH?

Answer 15

ACTIVATED

Question 16

Does RhoA INHIBIT or ACTIVATE cofilin?

Answer 16

INHIBITS

RhoA dephosphorylates cofilin back into its active form

Question 17

Oocyte arrest is maintained by

Answer 17

a cAMP pathway via cummulus cells and gap junctions

Question 18

Phosphodiesterases (PDEs) hydrolyze

Answer 18

cAMP.

Question 19

What the effects of PDEs on oocytes

Answer 19

low levels of cAMP and the oocyte leaving arrest ->maturation

Question 20

How do oocytes stay in arrest in the presence of PDEs?

Answer 20

They recieve cGMP from the surrounding cumulus and granulosa cells via gap junctions. THe PDEs hydrolize the cGMP instead of the cAMP.

i.e the PDE is too busy hydrolyzing cGMP to hydrolyze cAMP

Question 21

True or False: cumulus cells and the oocyte are physically and metobalically coupled by gap junctions

Answer 21

TRUE

High quality cumulus cells surround the oocyte and transfer nutrients, metabolites and singals to the oocyte

Question 22

What is the process of oocytes undergoing maturation?

Answer 22

A surge of LH leads to a drop in cGMP levels, this leads to cAMP being hydrolyzed by PDE and low cAMP levels. the result is oocyte maturation.