Lipid membranes

Question 1

Function on membranes

Answer 1

barrier
accumulate nutrients
energy transduction 
facilitate cell motion
assist in reproduction 
modulate signal transduction 
mediate cell cell interactions

Question 2

Lipid bilayers can form in various ways

Answer 2

unilamella vesicles (liposomes)
multilamellar vesicles

Question 3

Fatty Acids form clusters when they react with

Answer 3

cations

Question 4

Mark Bretcher showed that

Answer 4

N-terminus of glycophorin is extracellular

C -terminus is intracellular

Question 5

Flippases vs floppases

Answer 5

Flip-in to out

Flop -out to in

Question 6

Types of membrane proteins

Answer 6

integral
peripheral
lipid anchored

Question 7

Peripheral proteins can be dissociated from the. membrane , how?

Answer 7

With Salt solutions, or changed in pH

Question 8

Intergral membrane proteins can be removed from the protein , how ?

Answer 8

detergents or organic solvents

Question 9

Examples of integral membrane proteins

Answer 9

bacteriorhodopsin and glycophorin

Question 10

Glycophorin is a

Answer 10

single transmembrane segment protein

Acts as a grease

Question 11

regarding glycophorin , N and C termini face which direction

Answer 11

N-extracellular

C-cytosol

Question 12

A 7 transmembrane protein

Answer 12

Bacteriorhodopsin

Question 13

Found in Gram negative bacteria and in mitochondria outer membrane

Answer 13

Porins

Question 14

Structure of a porin

Answer 14

Beta sheet closes to form beta barrel which is hydrophilic on the inside.

Question 15

Four types of Lipid Anchored Membrane Proteins

Answer 15

1. Amide linked myristoyl anchors
2. Thioester linked fatty acyl anchors
3. Thioether linked prenyl anchors
4. Glycosyl phosphatidylinositol anchors

Question 16

A common anchoring protein is

Answer 16

N-myristoyl anchoring motif

Question 17

N-myristoylation always occurs at

Answer 17

An N-terminal glycine residue

Question 18

Examples of Myristoyly anchors .. what the main point

Answer 18

Not always attached to a membrane

Question 19

Palmitoylation always occurs where?

Answer 19

Cystein residues in the C terminal

Question 20

Amide linked Myristoyl anchors

Answer 20

Myristic acid

Question 21

Thioester linked Acyl Anchors

Answer 21

palmitate is most common , myristate, strearate, oleate are also all found.

Question 22

Proteins containing the C-terminal sequence , CAAX can undergo

Answer 22

prenylation reactions that put either geranylgeranyl or faresyl groups at the cystein side chain

Question 23

Prenylation is accompanied by the

Answer 23

removal of the AAX peptide bond and methylation of the carboxyl group of the cysteine residue , which has become the C-terminal residues.

Question 24

Most elaborate anchors

Answer 24

Glycosyl Phosphatidylinositol Anchors

examples are surface antigens, adhesion molecules, cell surface hydrolases

Question 25

Glycosyl Phosphatidylinositol Anchors are alway attached at ?

Answer 25

C-terminal residue

Question 26

Core of glycosyl phosphatidylinositol anchors

Answer 26

three mannose , and a glucosamine