Membranes and Receptore

Question 1

General Function of Biological Membrane (5)

Answer 1

continuous, highly selective permeability barrier.
control enclosed chemical environment.
recognition.
communication.
signal generation in response to stimuli

Question 2

Compostion of a biological membrane

Answer 2

40% lipids
60% proteins
1- 10% carbohydrates
(20% water hydrogen bonded to bilayer)

Question 3

make up of a phospholipid

Answer 3

2 x fatty acid
glycerol
phosphate
head group

Question 4

Types of head group in a phospholipid

Answer 4

choline
amino acid (serine)
amine ( ethanolamine {alcohol added to amine})
sugar (cyclohexane- inositol)

Question 5

exception to usual structure of phospholipid and how it varies

Answer 5

sphingomyelin- not based on glycerol

Question 6

2 types of head group in a glycoprotein and what they are

Answer 6

cerebroside- sugar monomer

ganglioside- oligosaccharide/ sugar mulitimer

Question 7

forces in a bilayer and where found

Answer 7

van der walls- between hydrophobic tails
non covalent ( electrostatic and H bonds) between hydrophic groups and water, and between hydrophillic groups

Question 8

feature of pure bilayer

Answer 8

very low permeability to ions and polar molecules

Question 9

types of mobility within the bilayer

Answer 9

flexion/ intrachain motion
lateral diffusion
fast axial rotation
flip flop

Question 10

types of mobility of membrane proteins

Answer 10

conformational change
rotation
lateral diffusion
NO FLIP FLOP

Question 11

why no flip flop movement of proteins in the lipid bilayer

Answer 11

too much energy is required
has to move the hydrophilic head through hydrophobic region,
would break the bilayer structure

Question 12

2 types of protein in a lipid bilayer and there properties

Answer 12

peripheral- bound to surface, electrostatic and H bonds, removed by changes in pH or ionic salt strength

Integral- Hydrophobic domain interactions, not removed by pH or ionic salt strength changes, removes by agents that compete with non polar interactions ( detergents or organic solvents)

Question 13

function of cholesterol in a lipid bilayer

Answer 13

resists changes to fluidity. forms H bonds to the phospholipids.
Increased temperature- phospholipids cant move apart- reduces chain motion
decreased temperature- phospholipids cannot move closer together- reduced chain packing

Question 14

how much of the lipids in a membrane is cholesterol on average

Answer 14

45%

Question 15

restrictions to membrane protein mobility

Answer 15

lipid mediated effect
membrane protein association-
-aggregates
- tethering (to x cellular matrix or intracellular matrix
- interactions with membrane proteins of other cells

Question 16

evidence for membrane proteins based on function

Answer 16

facillitated diffusion
ion gradient
specifity of cell response

Question 17

e#vidence for membrane proteins based on biochemical methods

Answer 17

freeze fracture

membrane fractionation + gel electrophoresis

Question 18

function of cytoskeleton in blood transport

Answer 18

needed to stop lysis when traveling through the capillary bed

Question 19

proteins involved in the cytoskeleton of a erythrocyte

Answer 19

spectrin a +B
Actin
Band 4.1
ankyrin
band 3
glycophorin A

Question 20

2 types of haemolytic anaemias

Answer 20

hereditary spherocytosis

hereditary elliptocytosis

Question 21

what is a right side out and inside out vessicle + where does it form

Answer 21

right side out is when the plasma membrane of a vessicle is the correct way round
inside out is when the plasma membrane is reversed
forms in endocytosis