Biochem quiz 1 membrane

Question 1

Why is the existence of the membrane important?

Answer 1

Membrane is important to compartmentalize the cell.

Question 2

Intracellular membranes are ________

Answer 2

dynamic

Question 3

Endocytosis

Answer 3

process by which cells take up extracellular molecules

Question 4

Exocytosis

Answer 4

mechanism for release of macromolecules in the cell

Question 5

what is the backbone of phosphoacylglycerols?

Answer 5

glycerol

Question 6

Characteristics of phophoacylglycerols

Answer 6

glycerol is the backbone, fatty acids are linked to C1 and C2 of the backbone, fatty acyl chains have varrying numbers of carbon and double bonds, ALL have a phosphate moiety linking to C3 of the backbone.

Question 7

All sphingolipids are derivatives of________

Answer 7

ceramide

Question 8

carb. moieties reside in the _______ side of the membrane

Answer 8

extracellular

Question 9

cholesterol is _____________ and found _______

Answer 9

very hydrophobic and found on interior of the PM

Question 10

How do lipids function in the PM?

Answer 10

Lipids dont just serve as structure, but they also regulate enzymes through lipid- protein interactions.

Question 11

What occurs when gauche confirmation increases?

Answer 11

The chain length is shortened and the cross-sectional area occupied by the hydrocarbon chain is increased.

Question 12

unsaturated acyl chains containing cis double bonds have__________than saturated acyl chains.

Answer 12

more membrane free volume ( membrane fluidity)

Question 13

What affect does cholesterol have on membrane fluidity?

Answer 13

Cholesterol has a condensing affect on neighboring phospholipids and decreases membrane fluidity.

Question 14

How does cholesterol affect gauche confirmation?

Answer 14

cholesterol abolishes gauche confirmation and reduces membrane free volume.

Question 15

under normal physiological conditions, lipids prefer to remain_______

Answer 15

PS and PE prefer to reside within the inner leaflet facing the cytosol

Question 16

Where is cholesterol most abundant?

Answer 16

Cholesterol is most abundant in the plasma membrane although it is synthesized in the ER

Question 17

Can lipids undergo spontaneous transfer?

Answer 17

yes, between membranes via the aqueous phase. Lipids can also be transferred between different membranes via protein-mediated processes.

Question 18

lateral organization of the membrane :

Answer 18

lipid rafts that are rich in cholesterol . certain proteins like to reside on rafts. Rafts are functional membrane domains.