lipids

Question 1

what atoms do lipids contain

Answer 1

hydrogen carbon oxygen

Question 2

how can a triglyceride molecule be described

Answer 2

non polar and hydrophobic (insoluble)

Question 3

what are the 2 types of lipids

Answer 3

phospholipids
triglycerides

Question 4

what are 4 main roles of lipids

Answer 4

energy yield
energy storage
insulation
hormonal comunication

Question 5

what are the monomers that makes up triglycerides

Answer 5

glycerol and 3 fatty acids

Question 6

what is the R group of triglycerides

Answer 6

methyl

Question 7

what is at each end of the fatty acids hydrocarbon chain in a trig

Answer 7

R group and a carboxyl group

Question 8

what is the shorthand chemical formula for a fatty acid

Answer 8

RCOOH

Question 9

how can fatty acids vary

Answer 9

• length of the hydrocarbon chain
• whether the hydrocarbon chain is unsaturated or saturated

Question 10

what are the 2 types of unsaturated chains

Answer 10

mono unsaturated
poly unsaturated

Question 11

what is the term cis- fatty acid used to describe

Answer 11

if the H atoms are on the same side as the double bond they are cis and are metabolized by enzymes

Question 12

if H atoms on opposite sides of the double bonds what is this known as

Answer 12

trans fatty acids

Question 13

what is a limitation of trans fatty acids

Answer 13

they cannot form enzyme substrate complexes so they cannot be metabolised

Question 14

what creates a mono unsaturated hydrocarbon chain

Answer 14

there must be 1 double carbon bond

Question 15

what creates a poly unsaturated hydrocarbon chain

Answer 15

more than 1 double bond on the carbon

Question 16

what is the difference between a phospho and trig lipid

Answer 16

phosphos only have 2 fatty acids while trigs have 3

Question 17

what replaces the 3rd fatty acid in a phospholipid

Answer 17

a phosphate ion

Question 18

how can a phospholipid molecule be described

Answer 18

non polar hydrophobic fatty acid tails with a polar hydrophilic head

Question 19

what makes a phospholipid head hydrophilic

Answer 19

the phosphate makes the head polar so it is soluble in water

Question 20

what does the term amphipathic mean

Answer 20

the molecule has both hydrophobic and hydrophilic parts.

Question 21

why is a bilayer able to be formed by phospholipids

Answer 21

because they are amphipathic

Question 22

what type of bonds form in a lipid between fatty acids and glycerol

Answer 22

ester

Question 23

when is an ester bond formed

Answer 23

when a hydroxyl (-OH) group from the glycerol bonds with the carboxyl (-COOH) group on the fatty acid

Question 24

what type of reaction is an ester bond and why

Answer 24

condensation because a H from glycerol combines with an OH from the fatty acid to create a H2O

Question 25

what type of lipid makes fats and oils

Answer 25

triglycerides

Question 26

what are fats and oils useful for in organisms

Answer 26

energy storage insulation buoyancy protection

Question 27

what makes trigs be good energy stores

Answer 27

the long hydrocarbon chains contain many carbon - hydrogen bonds with little oxygen so when trigs are oxidised during cellular respiration the bonds break which released energy to produce ATP

Question 28

why is trigs being hydrophobic good in terms of energy storage

Answer 28

because it means they do not cause osmotic water uptake in cells so more is able to be stored

Question 29

how do plants store trigs

Answer 29

in the form of oils in their seeds

Question 30

how do mammals store trigs

Answer 30

as oil droplets in adipose tissue

Question 31

how do trigs from metabolic water

Answer 31

the carbon - hydrogen bonds release a large number of H2O molecules which is good for desert animals and bird and reptile embryos in shells

Question 32

how does trigs being good insulators affect the nervous system

Answer 32

they form part of the myelin sheath that surrounds nerve fibres which insulates them which increases the transmission of impulses

Question 33

how are trigs good insulators

Answer 33

they compose part of the adipose tissue below the skin which acts as an insulator against heat loss

Question 34

why are trigs buoyant

Answer 34

they make the fat tissue less dense which makes floating easier

Question 35

NOTE more on phospholipid function in its own topic