Lipids

Question 1

Classify simple lipids

Answer 1

Triglycerides- have alcohol glycerol

Waxes

Question 2

Classify cpd lipids

Answer 2

Phospholipids- glycerophospholipid, sphingophospholipid

Glycolipid- cerebroside, ganglioside, globoside, sulfatide

Lipoprotein- chylomicron, VLDL, LDL, HDL

Question 3

Classify and state the use of each type of phospholipid

Answer 3

Glycerophospholipid
Lecithin- contains choline- dipalmitoyl lecithin-lung surfactant that prevents the collapse of alveoli

Cephalin- contains ethanolamine- Thromboplastin contains mainly cephalins- blood coagulation

Phosphotidylinositol- contains myoinositol- 2nd messenger for oxytocine&vasopressin

Phosphotidylserine

Plamalogens- f.a of C1 of glycerol is linked by a ether bond instead of ester bond- in myelin& cardiac muscle- platelet activating factor

Lysophospholipid

Cardiolipin

Sphingophospholipid- alcohol sphingosine
Eg. Sphingomyelin- membrane of nerve tissue

Question 4

Classify and state the function of each type of glycolipid

Answer 4

Cerebrosides- simplest glycolipid
Galactocerebroside-nerve tissue membrane
Glucocerebroside- non neural tissue

Sulfatide- ceramide +monosaccharide containing ester

Globoside- ceramide + oligosaccharide- determinants of ABO blood group system

Ganglioside- ceramide + oligosaccharide + N-acetyl neuraminic acid

Question 5

State the Functions of the diff. Lipoproteins

Answer 5

Chylomicron- intestine- transport lipid from intestine to peripheral tissue

VLDL- liver- transport triacylglycerol from liver to peripheral tissue

LDL- plasma VLDL- transport cholesterol from liver to peripheral tissue

HDL- liver and intestine- transport free cholesterol from peripheral tissue to liver

Question 6

What are eicosanoids synthesised from

Answer 6

Arachidonic acid

Question 7

Examples of eicosanoids

Answer 7

Prostaglandins, thromboxanes, leukotriens

Question 8

Classify prostaglandins

Answer 8

Classified depending on cyclopentane ring- A B C DE F G H I

Sub classifieds cording to no. Of double bonds in side chains

16 naturally occurring prostaglandins, 7 found in body

Question 9

State the function of prostaglandins

Answer 9

Regulate synthesis of cAMP

Smooth muscle contraction and relaxation- pregnancy- promote uterine contraction

Inflammatory response- increase capillary permeability

Promote platelet aggregation

Decrease blood pressure

Elevate body temperature

Suppress gastric secretions

Question 10

State the Functions of thromboxanes (TX)

Answer 10

TXA2
Produced by platelets- promotes platelet aggregation

Raises blood pressure- causes contraction of arterial wall smooth muscle

Question 11

State the functions of leukotrienes (LT)

Answer 11

LT- Facilitate chemo taxis, inflammation, allergic reactions

LTC4, LTD4- contraction of lung muscles and constrict pulmonary airways - overproduction causes asthma

LTB4- attracts neutrophils and eosinophils to sites of inflammation

Question 12

Definition of lipids

Answer 12

Organic substances that are insoluble in water but soluble in organic solvent such as chloroform

Question 12

State the Functions of thromboxanes (TX)

Answer 12

TXA2
Produced by platelets- promotes platelet aggregation

Raises blood pressure- causes contraction of arterial wall smooth muscle

Question 13

State the functions of leukotrienes (LT)

Answer 13

LT- Facilitate chemo taxis, inflammation, allergic reactions

LTC4, LTD4- contraction of lung muscles and constrict pulmonary airways - overproduction causes asthma

LTB4- attracts neutrophils and eosinophils to sites of inflammation

Question 14

Classify fatty acids

Answer 14

Straight chain fatty acids- saturated, unsaturated

Branched chain f.a

Substituted f.a

Cyclic f.a

Question 15

Functions of f.a

Answer 15

Building blocks for phospholipids and glycolipids

Derivatives serve as hormones

Serve as major fuel for most cells

Question 16

What are essential f.a

Answer 16

Reqd for optimal health
Cannot be synthesised by body
Linoleic acid and linolenic acid

Arachidonic acid is synthesised from linolinic acid therefore in deficiency of linolenic acid, Arachidonic acid become essential

Question 17

Functions of essential f.a

Answer 17

Synthesis of eicosanoids
Maintenance of structural integrity- imp. Constituents of phospholipids in cell membrane.
Development of retina in brain ( docohexaenoic acid )
Antiatherogenic effect- increase esterification and excretion of alcohol

Question 18

What are micelles?

Answer 18

In aq. Systems- polar phospholipid- disperse to form micelles

Hydrocarbon tail of phospholipid hidden from aq. environment
Hydrophilic heads are exposed on the surface facing the aq. medium

Question 19

What is a liposome?

Answer 19

artificially formed aq. vesicles enclosed by a lipid bilayer

Formed by- suspending phospholipid in aq. medium and sonicating ( agitating by high freqn sound waves)

Used to- study membrane permeability, deliver drugs to cells

Question 20

What are detergents?

Answer 20

Amphipatic molecules that Form micelles in aq. Solution

Eg. Bile acids, bile salts

Question 21

Function of cholesterol

Answer 21

Major structural constituent of cell

Precursor for: steroid hormones ( estrogen), bile acids, Vit D

Question 22

Classify lipids

Answer 22

Simple- esters of fatty acids with various alcohols

Compound- esters of fatty acids with alcohols that have a prosthetic grp

Derived- obtained after hydrolysis of simple and cpd lipids

Question 23

What are micelles?

Answer 23

In aq. Systems- polar phospholipid- disperse to form micelles

Hydrocarbon tail of phospholipid hidden from aq. environment
Hydrophilic heads are exposed on the surface facing the aq. medium

Question 24

What is a liposome?

Answer 24

artificially formed aq. vesicles enclosed by a lipid bilayer

Formed by- suspending phospholipid in aq. medium and sonicating ( agitating by high freqn sound waves)

Used to- study membrane permeability, deliver drugs to cells

Question 25

What are detergents?

Answer 25

Amphipatic molecules that Form micelles in aq. Solution

Eg. Bile acids, bile salts

Question 26

How are fatty acid carbon atoms numbered?

Answer 26

F.a carbon Atoms are numbered starting from the carboxyl (COOH) terminus

Carbon atom 2&3 = alpha + beta

Methyl (CH3) Carbon atom = omega carbon

Question 27

What are the Systems representing the double bonds of the fatty acids?

Answer 27

C-system

Omega system:
omega 9- oleic acid
Omega 6- linoleic and Arachidonic acid
Omega 3- linolenic acid