Lecture 7 and 8

Question 1

Membrane lipids are ______/

Answer 1

Amphiphilic

Question 2

How thick is the lipid membrane?

Answer 2

5nm (50 angstrom)

Question 3

What name is given to the carboxl and methyl end of a fatty acid?

Answer 3

Delta and omega (respectively)

Question 4

Give an example of a glycerophospholipid

Answer 4

Phosphatidyl-choline

Question 5

What is the structure of phosphatidyl-choline?

Answer 5

Choline, phosphate, glycerol, hydrocarbon tails

Question 6

Why do membrane lipids favor a bilayer of two leaflets over a micelle?

Answer 6

Cylindrical shape

Question 7

What do membrane sheets favour the formation of?

Answer 7

Liposomes (membrane lipid balls, energetically favorable)

Question 8

What are exosomes and what do they do?

Answer 8

Liposomes released by cells, cell to cell communication

Question 9

Membranes can be split into glycerophospholipids and ________

Answer 9

Sphingolipids (S for serine linker)

Question 10

What three lipid components can comprise a membrane?

Answer 10

Phosphoplipids, glycolipids, cholesterol

Question 11

Name two categories of phospholipids.

Answer 11

Amino and choline phospholipids

Question 12

Name 4 glycerophospholipids

Answer 12

Phosphatidyl:
- Inositol
-Athanolamine
-Serine
Choline

Question 13

What are the three coponents of cholesterol?

Answer 13

Polar head group
Rigid steroid ring structure
Nonpolar hydrocarbon tail

Question 14

How do cholestrol interact with glycerophospholipid?

Answer 14

Associates with head the lipid, it becomes more densely packed, less fluid, less permeable

Question 15

How do cholesterol interact with sphingolipids?

Answer 15

Sphingolipids have longer, straighter chains, cholesterol reduces packing density and keeps membrane fluid

Question 16

Where are cholesterol enriched sphingolipids found?

Answer 16

Membrane invaginations (Caeolae and clathrin-coated pits)

Question 17

What is cholesterol an important starting molecule for?

Answer 17

Bile salts
Vitamin D
Steroids (cortisol and aldosterone)
Sex hormones (progesterone, oestrogen and testosterone)

Question 18

Where are fat droplets originating from?

Answer 18

Endoplasmic reticulum, bound in monolayer (contents hydrophobic)

Question 19

What are glycolipids based on?

Answer 19

Ceramide

Question 20

What glycolipid is the receptor for the cholera toxin?

Answer 20

GM1 ganglioside

Question 21

What do glycolipids do?

Answer 21

Protect from the environment, cell to cell contact, important in lipid raft generation function

Question 22

What membrane proteins bind sugars and contain glycolipids?

Answer 22

Lectins

Question 23

Why are hepatocytes enriched with phsophatidylcholine?

Answer 23

Secrete PC into the bile

Question 24

Why is the ER low in cholesterol and high in glycerophospholipids?

Answer 24

Makes it more fluid for protein insertion

Question 25

Myelin is enriched in what type of lipid?

Answer 25

Glycolipids- insulate nerve axon

Question 26

What are some limitations to the fluid mosaic model?

Answer 26

- Some proteins are anchored or tied to extracellular/intracellular matrix/cytoskeleton Lipids can be signalling molecules Lipids modules membrane protein activity

Question 27

What % of coding capactiy of the human genome is for membrane proteins?

Answer 27

26%

Question 28

What % drug targets are for membrane proteins?

Answer 28

60%

Question 29

Name a membrane channel.

Answer 29

Channel CFTR (chloride channel. Mutations lead to cystic fibrosis)

Question 30

Name a transporter protein.

Answer 30

Transporter ABCB1 (drug efflex plump, causes multidrug resistance)

Question 31

Name an adherent gap junction between cochlear cells.

Answer 31

Connexin 26

Question 32

Name a receptor.

Answer 32

Receptors FGFR3 _FGF

Question 33

What does FGFR3 + FGF do?

Answer 33

Changes gene expression, decreased poliferation of bone cells

Question 34

Name a membrane enzyme

Answer 34

Phospholipase C

Question 35

How is glucose uptaken into a cell?

Answer 35

SGLT1 symporter | Na+ driven glucose symport

Question 36

How is cellular sodium kept low in intestinal epithelial cells?

Answer 36

Na+K+ ATPase (primary active pump) pumps out 3 sodium and in 1 pottasium ion

Question 37

What protein facilitates glucose diffusion into the extracellular fluid?

Answer 37

GLUT2

Question 38

What three active transporters were identified to cause progressive familiar intrahepatic cholestasis?

Answer 38

ATP8B1 ABCB4 ABCB11

Question 39

What is a dominant disease caused by deficiency in receptor-mediated endocytosis?

Answer 39

Familiar hypercholesterolaemia

Question 40

What domain is deleted in familial hypercholesterolameia?

Answer 40

Clathrin interaction domain, affects 1 in 500 UK popn.

Question 41

What does CFTR do?

Answer 41

Releases Cl- to induce flow of Na+ and water to reduce viscocity of surface mucous

Question 42

What drug helps as a chemical chaperone to help delta F508 fold to treat CF?

Answer 42

Lumacaftor

Question 43

What is Ivacaftor an example of?

Answer 43

A potentiator- increases ability of channel to open for G551D patients