Lipids and membrane structures

Question 1

Definition of lipids

Answer 1

Insoluble in water, soluble in fat/organic solvents. Energy state, precursors for vitamins, steroid hormones, bile acids and phsopholipids

Question 2

Definition of fully saturated

Answer 2

No C=C in FA

Question 3

Definition of unsaturated

Answer 3

1 C=C in FA

Question 4

Definition of polyunsaturated

Answer 4

Many C=C in FA

Question 5

Definition of phospholipases

Answer 5

Important class of enzymes that bind to membrane and selectively hydrolyses components of phospholipids

Question 6

Structure of a triglyceride

Answer 6

Ester of 3 FA/glycerol

Question 7

How to form and hydrolyses triglyceride

Answer 7

Dehydration/synthesis

Hydrolysis

Question 8

Structure of a fatty acid

Answer 8

Long chain aliphatic carboxylic acids

Metabolised via B-oxidation pathway => ATP generation

Question 9

Naming unsaturated triglycerides

Answer 9

(18:1 ∆9)
No of C in chain
No of C=C
Position of C=C in relation to COOH

Question 10

Describe the fluid mosaic model of membrane structure

Thickness of membrane

Answer 10

Islands of proteins in a sea of lipid

4-5nm

Question 11

Structure of a phospholipid

Answer 11

PO3 2- and serine/choline/ethanolamine/inositol
Glycerol
2 FA

Question 12

Structure of a glycolipid

Answer 12

Carbohydrate
Glycerol
2 FA

Question 13

Properties of phospholipid

Answer 13

Bilayer in aqueous environment
Polar head group (PO3 2- serine, choline, ethanolamine, inositol)
2FA side chains
Ester bond to glycerol, hydrophobic
Amphipathic

Question 14

Structure of sphingomyelin

Answer 14

Choline
Phosphate
Ceramide Sphingomyelin
Fatty acyl chain

Question 15

Features of the lipid bilayer

Answer 15

Asymmetrical

Very fluid, ease which lipid molecules move about, don’t move from 1 plane to another

Question 16

Regulation of fluidity

Answer 16

Lipid composition of membrane defines fluidity
Increased SCFA, decreased VDW, increased fluidity
Increased UFA, decreased VDW, increased fluidity
Increased cholesterol, decreased random movements of polar heads, decreased fluidity

Question 17

Structure of a lipid raft

Answer 17

Specialized membrane micro domain
More ordered, less fluid, section of limited movement
Increased cholesterol and sphingomyelin
Allows close interaction between receptors and signaling molecules

Question 18

Types of membrane protein

Answer 18

Structural
Receptors
Ion channels
Transporters
Enzymes

Question 19

Function of structural proteins

Answer 19

Cell-cell contact, attachment of cytoskeleton

Question 20

Function of receptor proteins

Answer 20

Signal recognition and transmission

Question 21

Function of ion channel proteins

Answer 21

Maintenance of ionic gradients and transmissions

Question 22

Function of tranporter proteins

Answer 22

Import and export of substrates

Question 23

Function of enzymes

Answer 23

Catalysis

Question 24

Organization of membrane proteins

Answer 24

Integral/intrinsic proteins
Anchored proteins
Peripheral/extrinsic proteins

Question 25

Properties of integral proteins

Answer 25

Embedded in bilayer | Most are transmembrane, spanning domains=a helices, b sheets

Question 26

Properties of anchored proteins

Answer 26

Anchored to membrane by covalent bonds with FA

Question 27

Properties of peripheral proteins

Answer 27

Attach to membrane surface by ionic interaction with integral proteins or with polar head groups of phospholipids

Question 28

Types of phospholipases

Answer 28

``` Phospholipase A1 (Ester between FA and G) Phospholipase A2 (Ester between FA and G) Phospholipase C (Ester between G and PO3 2-) Phospholipase D (Ester between PO3 2- and polar head) ```

Question 29

High salt/urea treatment on peripheral, anchored and integral proteins

Answer 29

Removed Remain Remain

Question 30

Detergent treatment on peripheral, anchored and integral proteins

Answer 30

Removed Removed Removed

Question 31

Phospholipase treatment on peripheral, anchored and integral proteins

Answer 31

Removed/Remain Removed Remain

Question 32

Detergent action of bilipid layer

Answer 32

Detergent molecules completely disrupt lipid structure, whole thing falls apart, can isolate proteins