Lecture 13

Question 1

primary lipid components of biomembranes

Answer 1

phosphoglycerides, sphingolipids, cholesterol

Question 2

types of phosphoglycerides

Answer 2

PE, PC, PS, PI

Question 3

sphingolipid is?

Answer 3

an amino alcohol with long hydrocarbon tail; example is glucosylcerebroside

Question 4

Sterol characteristics (3)

Answer 4

nonpolar hydrocarbon tail; rigid, planar ring; polar hydroxyl group

Question 5

cholesterol synthesis locale?

Answer 5

on ER (mainly in liver)

Question 6

what motions can lipids have in a lipid bilayer

Answer 6

rotation, flexion, lateral diffusion; very RARELY you can get flip-flop

Question 7

flipases do?

Answer 7

flip membrane lipids from one leaflet to another, this helps keep membranes asymmetric. synthesized at cytosolic face

Question 8

Each bilipid membrane is the same (t/f)

Answer 8

false. they have cytosolic faces and exoplasmic faces

Question 9

what is evenly distributed between inner and outer layer of bilayer?

Answer 9

cholesterol

Question 10

membranes usually contain __ and ___

Answer 10

integral and peripheral membrane proteins

Question 11

the peripheral membrane protein does not enter __

Answer 11

the hydrophobic core of bilayer

Question 12

integral membrane protein features?

Answer 12

alpha helices that attract the fatty acyl side chains

Question 13

what cell membrane proteins are distributed asymmetrically?

Answer 13

all transmembrane proteins (and glycolipids, even though thats not a protein)

Question 14

where are carbohydrate chains attached to protein?

Answer 14

exoplasmic surface of protein

Question 15

Long-chain lipids attach to ?

Answer 15

attach to gly or cys

Question 16

glycophorin is major thing in?

Answer 16

membrane protein of erythrocytes in junctional complex, provides a negative charge on the cell

Question 17

what do peripheral proteins do?

Answer 17

associate with integral membrane proteins; or, bind to phospholipid head groups

Question 18

GCPR transmembrane receptors are involved in?

Answer 18

signaling, olfaction, and drugs

Question 19

How do you tell the difference between peripheral and integral membrane proteins?

Answer 19

detergents will dissolve peripheral proteins below CMC; detergents will dissolve integral proteins at or above CMC by creating a micelle

Question 20

microdomain is?

Answer 20

lipids that cluster together that are unique. aka liquid-ordered state

Question 21

signal transduction proteins associate with

Answer 21

lipid rafts. if they exist.

Question 22

what is FRAP? what can it see?

Answer 22

fluorescence recovery after photobleaching; usually antibody with tag that attaches to protein in plasma membrane. if you bleach one part of it, you can see lipid membrane diffusion. NOT ALL PROTEINS/LIPIDS DIFFUSE

Question 23

Why are some lipids or proteins stationary in the lipid bilayer?

Answer 23

may attach to a receptor, internal cytoskeleton, or another cell interaction

Question 24

spectrin heterodimers made of? associates with?

Answer 24

repeating subunits; associates with beta-subunit, N-terminus with actin (F-actin or actin filaments)

Question 25

junctional complex is where??

Answer 25

spectrin molecule hub which attaches to little strands of actin filaments

Question 26

Band 3: what does it associate with

Answer 26

It attaches to Spectrin INDIRECTLY, through ankryin

Question 27

hereditary spherocytosis is a disease of ___

Answer 27

alpha and beta spectrin, protein 4.2, and band 3, ANKYRIN defects are most common

Question 28

what CAN permeate the phospholipid bilayer of the cell?

Answer 28

gases, small uncharged polar molecules

Question 29

three types of membrane transporters?

Answer 29

pumps, channels, ___porters

Question 30

pumps do what?

Answer 30

use ATP energy for active transport AGAINST the gradient (example is Na/K pump)

Question 31

ion channels do what

Answer 31

USUALLY transport ions with facilitated diffusion to achieve high rates of movement WITH gradient

Question 32

___porters do what

Answer 32

these do secondary active transport symporter = two molecules in same direction antiporter = two molecules in different directions

Question 33

dixgoxin works by what mechanism?

Answer 33

its a Na/K ATPase inhibitor; it helps the heart beat with a stronger and more regular beat

Question 34

NCX does what

Answer 34

its a cation antiporter; secondary active transport; uses Na gradient made by ATPase to move Ca2+ outta da cell

Question 35

What inhibits Na/Ca exchange

Answer 35

digoxin INDIRECTLY inhibits NCX because the ATPase is blocked that provides the sodium gradient