lecture 8

Question 1

Proteins can stably associate with membranes via: (3)

Answer 1

Hydrophobic transmembrane segments
Posttranslationally added lipid groups that are covalently linked to proteins
Association with other membrane localized proteins

Question 2

Phospholipids that have shorter fatty acid tails or tails which contain unsaturated hydrocarbons cause membranes to be

Answer 2

More fluid

Question 3

When observing the movements of phospholipids in membranes, which of the following occurs least frequently

Answer 3

Movements between the leaflets of a membrane bilayer

Question 4

DO All transmembrane proteins float and diffuse freely in the bilayer of the plasma membrane in the same manner as phospholipids?

Answer 4

NO

Question 5

DO Membrane compartments in eukaryotic cells maintain lipid bilayers whose contents are typically symmetric in their distribution across both leaflets

Answer 5

NO the are asymmetric

Question 6

Proteins that aid the movement of phospholipids from one leaflet of a membrane bilayer to another are known as:

Answer 6

Flippases

Question 7

The best way to determine if a protein is able to move in a membrane would be

Answer 7

Fluoresence Recovery After Photobleaching Experiment (FRAP)

Question 8

Membranes provide cells control over by

Answer 8

1 receiving info
2 import and export of molecules
3 capacity for movement and expansion

Question 9

_____ is important for its role in ordering the _______ ________
that form
membrane bilayers

Answer 9

Water,amphipathic phospholipids

Question 10

Formation of closed circular _____ and compartments

is energetically favored in aqueous environments

Answer 10

vesicles

Question 11

Cholesterol is an ______ molecule. with an ___ polar head

Answer 11

amphipathic, OH

Question 12

Two of the major components of the lipid bilayer

Answer 12

Phospholipids and Cholesterol

Question 13

3 major phospholipids

Answer 13

Phosphatidylcholine
Phosphatidylethanolamine
Phosphatidylserine

Question 14

how do Phospholipids move and __ ___ rareley occurs

Answer 14

• Rotation, Diffusion, Flip-flop

Question 15

Proteins and Glycolipids - ____ most relevant parameter of movement

Answer 15

Diffusion

Question 16

saturated = _______ = ________

Answer 16

better packing less fluid

Question 17

Unsaturated = _______ = ________

Answer 17

worse packing more fluid

Question 18

Length of tails short = _______ = ________

Answer 18

less well packed = more fluid

Question 19

the Distribution membrane of subtypes are

Answer 19

in rafts or islands

Question 20

An increase in cholesterol will tend to make membranes:

Answer 20

Stiffer/less permeable

Question 21

Cholesterol and other sterols help control

fluidity, filling in spaces between

Answer 21

phospholipids

Question 22

________is also important to the formation of ____ ____which are enriched in _____ ______whose diffusion is more limited

Answer 22

Cholesterol, lipid rafts, signaling proteins

Question 23

what are some ways Proteins play major roles in modulating membrane dynamics and organization

Answer 23

flippases and scramblases

fusion catalysts

‘coupling’ proteins for other proteins
diffusion barriers

Question 24

New membrane phospholipids are first synthesized and inserted into membranes where

Answer 24

The cytosolic surface of the ER

Question 25

scramblases catalyzes

Answer 25

the transfer of random phopholipids from one monolayer to another

Question 26

flippases catayzes

Answer 26

transfer of specific phospholids to cytosolic monolayer

Question 27

______trafficking helps distribute phospholipids from the ER cytosolic face to other compartments.

Answer 27

Vesicle

Question 28

Cellular membranes are __________. _______

also generate and maintain this

Answer 28

asymmetric –Flippases

Question 29

Membranes form largely by ____ docking and fusion – this establishes and asymmetry of the contents

Answer 29

vesicle, polarity

Question 30

vesticles can be tranfered fron the

Answer 30

Endoplasmic –>golgi

Reticulum vise versa

Question 31

Glycolipids and glycoproteins occur only or mainly in the ___ ____ of the plasma membrane because of their synthesis on the ___ ___of the Golgi

Answer 31

outer leaflet, interior face

Question 32

what are some examples of plasma membrane proteins

Answer 32

transporters, ion channels, anchors, receptors, enzymes

Question 33

3 mechanisms for membrane localizatin of proteins

Answer 33

Integral Membrane Proteins

Lipid anchor addition Peripheral membrane proteins

Question 34

Integral Membrane Proteins, are ofthen Membrane Associated by

Answer 34

alpha helix or beta sheet presentinga hydrophobic face to the lipid bilayer

Question 35

in Transmembrane

domains in alpha helices

Answer 35

helices – 
hydrogen bonds 
  “occupy” dipoles in 
   peptide bonds
hydrophobic R groups

Question 36

Membrane spanning proteins are typically extracted from membranes by using:

Answer 36

Addition of detergents such as SDS

Question 37

___ ____ can be used to
break protein-protein
interactions,

Answer 37

salts and urea, proteins in the periphery

Question 38

lectin is a ____ receptor that ________ bind to

Answer 38

adhesion oligosaccarides bind to

Question 39

proteins in the nucleus can directly go to

Answer 39

er

Question 40

proteins made in the cytosal can go to what intracelluar comparments

Answer 40

neucleus, chloroplast,mitochondrion,peroxiome, er