Lipids and Plasma Membrane

Question 1

structure of fatty acids

Answer 1

long hydrocarbon chain with carboxyl group at one end

Question 2

conformation of bonds in unsaturated fatty acids

Answer 2

double bonds are cis

Question 3

glycerolipids

Answer 3

esters of glycerol and fatty acids (Ester = COOR)

Question 4

structure of lipids that make up cell membranes

Answer 4

derivative of glycerol - two hydroxyl groups are ester linkages to fatty acids, third is attached to polar head-group through a phosphate.

Question 5

backbone of glycerophospholipids

Answer 5

phosphatidic acid

Question 6

most abundant glyerophopholipids

Answer 6

ethanolamine, choline, serine attached to phosphate group

Question 7

names of glycerophospholipids in cell membrane

Answer 7

PE: phosphatidylethanolamine
PC: phosphatidylcholine
PS: Phosphatidylserine
PI: phosphatidylinositol (less common but functions as precursor to signaling molecules produced in response to extracellular signals)

Question 8

2nd most common class of membrane lipid

Answer 8

sphingolipids

Question 9

describe sphingolipid structure

Answer 9

derived from sphingosine backbone and have to long hydrocarbon chains but no phosphate group

Question 10

name of sphingolipids

Answer 10

ceramide, sphingomyeline, glycolipids

Question 11

defects in metabolism of sphingolipids responsible for

Answer 11

lysosomal storage diseases

Question 12

membrane lipids

Answer 12

glycerophospholipids, sphingolipids, cholesterol

Question 13

structure of cholesterol

Answer 13

multi-ring structure (steroid nucleus), a hydrocarbon tail, and a hydroxyl group

Question 14

what is the polar part of cholesterol

Answer 14

the hydroxyl group

Question 15

negatively charged phospholipids names and where they are found

Answer 15

phosphatidylserine
Phosphatidylinositol
* usually on cystolic side of bilayer

Question 16

what is found on extracellular side of bilayer

Answer 16

PC, sphingomyelin, glycolipids

Question 17

what is found in both monolayers

Answer 17

cholesterol

Question 18

what does increasing the concentration of cholesterol in a membrane do

Answer 18

decreases its permeability to small polar molecules such as water

Question 19

integral membrane proteins

Answer 19

directly inserted in the lipid membrane or covalently bound to other groups that are inserted

Question 20

peripheral membrane protein

Answer 20

associated with the

Question 21

what proteins contain regions that span the membrane

Answer 21

B barrel buried in membrane proteins, transmembrane alpha helical proteins

Question 22

where are beta barrel found

Answer 22

burined in membrane proteins in outer membranes of gram negative bacteria and cell wall of gram positive… NOT found in PM of eukaryotes, only in outer membrane of mitochondria

Question 23

transmembrane protein characteristics

Answer 23

1. contain predominantly hydrophobic side chains that interact with lipid bilayer
2. Residues that interact with the phospholipid head groups tend to have positive side chains because of the negative charge of phospholipids
3. Intracellular regions close to the membrane tend to be abundant with positively charged residues, which often interact with teh particular lipids in these regions
4. Transmembrane residues that face a polar channel have polar side chains