2.1.2 lipids

Question 1

what are the general properties of lipids

Answer 1

contain C H O
non polar molecules = non-soluble
they are soluble in organic solvents
are macro molecules

Question 2

explain the structure of triglycerides

Answer 2

contains 1 glycerol molecule + 3 fatty acids
glycerol = alcohol
FA = carboxylic acids w/ carboxyl group

Question 3

describe the structure of fatty acids

Answer 3

have carboxyl groups and long hydrocarbon chains
hydrocarbon chain = HYDROPHOBIC
also contain variable R group = differentiates between types of FA

Question 4

explain the difference between saturated and unsaturated acids

Answer 4

saturated acid = only SINGLE BONDS between carbons
unsaturated = at least ONE DOUBLE BOND between carbons

Question 5

describe the difference between mono and poly unsaturated FA

Answer 5

one double bond = mono-unsaturated
multiple double bonds = poly-unsaturated

Question 6

why are some lipids liquid at room temp while others are solid?

Answer 6

double bonds between carbons cause molecules to bend
= can’t be closely packed = liquid at rt

Question 7

how are triglycerides formed

Answer 7

condensation reaction
FA + glycerol group contain OH groups
interact + form ester bonds
produce water
ESTERFICATION

Question 8

what are the properties of triglycerides?

Answer 8

energy store = high ratio of C-H bonds to C atoms; lots of E stored per mol
metabolic water source = high ratio of H to O; oxidises + releases H20
insoluble = large molecule; wont affect water potential
relatively low mass = compared to muscles; can store E w/o increasing weight

Question 9

describe the structure of phospholipids

Answer 9

contain 1 glycerol mol, 2 FA mols, and 1 phosphate group
phosphate ions found in cytoplasm
phosphate group = hydrophilic
FA tail = hydrophobic

Question 10

explain the formation of the phospholipid bilayer

Answer 10

phosphate heads face outwards towards aqueous environments (inside and outside of cell)
FA tails face away from aqueous environment

Question 11

why is the cell membrane important

Answer 11

helps to separate cell from outside environment

Question 12

explain what a sterol is

Answer 12

steroid alcohols
4 carbon ring structure w/ OH group
have dual hydrophilic and hydrophobic properties
(OH group = polar; rest of mol = hydrophobic)

Question 13

describe the structure of cholesterol

Answer 13

hydrocarbon ring structure; attached to hydrocarbon tail
polar OH group attached
made in liver + intestines

Question 14

explain the importance of cholesterol in cell membrane

Answer 14

positioned between phospholipids + binds to FA tail
provides stability + reduces rigidity of cell
ensures it remains stable even in temp fluctuations
produces vitamin D, steroid hormones, and bile

Question 15

explain the roles of lipids

Answer 15

membrane formation&raquo_space;> hydrophobic barriers bc of phospholipid bilayer; gives cell flexibility; helps transfer lipid soluble components
hormone production&raquo_space;> steroid hormones
electrical insulation for impulse transmission
waterproofing
long term energy store&raquo_space;> high E compared to carbohydrates; stored under skin and vital organs