4- lipids

Question 1

What are lipids

Answer 1

Hydrophobic 
Insoluble 
Long hydrocarbon chain 
many types 
Fatty acid plus ...

Question 2

Main uses of lipids

Answer 2

• Storage of energy ( fatty acids attach to glycerol to make triacyglycerol) , main storage lipid
• Forming membranes - membrane lipids include phospholipids and cholesterol
• Signalling with and between cells

Question 3

Main types of lipid

Answer 3

Triglyceride
Phospholipids
Lipid derivatives e.g. sterols, bile salts and vitamin D

Question 4

Fatty acid

Answer 4

Oxidized to release energy in cells ( respiration )

Hydrocarbon chain with carboxylic acid group at the end

Question 5

SATURATED fatty acid

Answer 5

Carbon chain has no double bonds

Question 6

UNSATURATED fatty acid

Answer 6

Have a double bond in chain chain

Cause KINK

Question 7

Monounsaturated vs polyunsaturated fatty acids

Answer 7

MONO = 1 double bond 
POLY= several double bonds

Question 8

Naming fatty acids

Answer 8

First number indicates number of carbons in a chain and second number is the number of double bonds
e.g.
18:4 ( delta 6 delta9 delta 12 delta 15)
Delta(number )for the position of the double bond from the carb acid end

OR

Omega ( number ) for the position of the double bond from the OTHER end

Question 9

Double bond for fat acids - effect

Answer 9

Makes molecule MORE fluid
More likely to be liquid at room temp
Kinks mean it cant pack as closely

Question 10

Triglycerol

Answer 10

3 fatty acids join onto a glycerol molecule

Main storage form of lipids, found in adipose tissue surrounding visceral organs and subcutaneous fat

Question 11

Phospholipid -Membrane lipid

Answer 11

• 2 fatty acid tails, glycerol and phosphate group
• Hydrophobic region caused by hydrocarbon chain of FA
• Hydrophilic region caused by phosphate group
• Glycerophopsholipids based on glycerol and sphingolipids based on sphingosine

form a BILAYER - tails in middle protected from the water - can bend around to form vesciles

Question 12

Cholesterol - membrane lipid

ROLE

Answer 12

Based on steroid structure
Moderates fluidity of membranes
Decreases membrane fluidity as it packs between other lipids, spreading them out
High levels of plasma cholesterol are associated with heart disease

Question 13

Amphiphatic

Answer 13

Means theres both a hydrophobic region and hydrophillic

Question 14

Lipid derivatives

Answer 14

Vitamin D - bone formation and calcium absorption
Steroid hormones - e.g. cortisol, oestrogen, progesterone
Bile salts- synthesised from cholesterol in the liver
Eicosanoids e.g. thromboxanes

Question 15

Carbohydrates

Answer 15

CH20
Hydrated carbon
Simple carbohydrates are called sugars = SWEET

Question 16

Main uses

Answer 16

• Energy storage, structure, recognition , adhesion

Question 17

Monosaccharides

Answer 17

Consist of an aldehydes of ketone with at least 2 alcohol groups
e.g. glucose, fructose, ribose

Question 18

disacchardies

Answer 18

common dietary sugars
Broken down by enzymes in intestinal brush border membrane
e.g. sucrose broke down by surcrase to form glucose and fructose

e. g. lactose broken down by lactase to form glucose and galactose
e. g. maltose broken down by maltase to form glucose and glucose

Question 19

Polysaccharides

Answer 19

MANY sugars joined together via glycosidic bonds to form polysaccharides
Can be same type ( homopolysacchardies ) or different types ( heteropolysaccharides )

Linear or branches
Energy storage and structural rigidity

Question 20

Storage polysaccharide

example

Answer 20

Starch in plants and glycogen in animals

Glycogen stores glucose molecules in the liver and muscle . Homopolysaccharide, highly branched
Starch i s the main dietary source of carbohydrate

Question 21

Structural polysaccharide and example

Answer 21

Carbs
e.g. cellulose is the main component of plant cell walls
Cellulose cannot be digested by humans butt is an important contributor to dietary fiber

Question 22

Glycoproteins and glycolipids

Answer 22

Carbs
Sugar groups found on the outside of the cell membrane
Basis of cell recognition and adhesion e.g. blood groups

Question 23

Proteoglyans

Answer 23

CArbs
Linked to large negatively charged heteropolysaccharides caused glycosaminoglycans ( GAGS)

Important roles in extra cellular matrix, acting as lubricants and shock absrobers

Arthiritis occurs when proteoglycans degrade