lipids

Question 1

name two groups of lipids

Answer 1

triglycerides and phospholipids

Question 2

describe the structure of a fatty acid

Answer 2

variable R group - hydrogen chain
COOH -carboxyl group

Question 3

describe the difference between saturated and unsaturated fatty acids

Answer 3

saturated : no C=C in hydrocarbon chain all fully saturated with H
unsaturated : one or more C=C double bond in hydrocarbon chain

Question 4

describe how triglycerides form

Answer 4

1 glycerol molecule and 3 fatty acids
condensation reaction
removing 3 water molecules
forming 3 ester bonds

Question 5

explain how the properties of triglycerides relate to their function

Answer 5

function - energy store
- high ratio of C-H bonds to carbon atoms in hydrocarbon chain : used in respiration to release more energy than same mass of carbohydrates
- non polar fatty acids insoluble in water : no effect on water potential of cell

Question 6

describe the difference in structure between triglycerides and phospholipids

Answer 6

one of the fatty acids of a triglyceride substituted by a phosphate group

Question 7

describe how the properties of phospholipids relate to its function

Answer 7

function: form a bilayer in cell membrane allowing diffusion of non polar or very small substances and restricting movement of polar molecules or larger substances

-phosphate heads are hydrophilic: attracted to water so point to water
- fatty acids are hydrophobic: repelled by water so point away

Question 8

describe the test for lipids

Answer 8

1. add ethanol shake then add water
2. positive = milky white emulsion