biological molecules unit 1

Question 1

what is a condensation reaction?

Answer 1

joining two molecules together creating a chemical bond and removing water

Question 2

examples of monomers and polymers

Answer 2

glucose = starch, cellulose, glycogen
amino acid = proteins
nucleotides = DNA and RNA

Question 3

what is a hydrolysis reaction?

Answer 3

breaks a chemical bond between two molecules and involves the use of water

Question 4

3 examples of monosaccharides

Answer 4

fructose, glucose, galactose

Question 5

3 examples of disaccharide

Answer 5

maltose, sucrose, lactose

Question 6

3 examples of a polysaccharide

Answer 6

starch, cellulose, glycogen

Question 7

define an monomer

Answer 7

smaller units that join together to form larger molecules

Question 8

define a polymer

Answer 8

molecules formed when many monomers join together

Question 9

describe the structure and functions of starch

Answer 9

insoluble = no osmotic effect in cells
large = does not diffuse out of cells
made from amylose:
- 1,4 glycosidic bonds
- compact
made from amylopectin
- 1,4 and1,6 glycosidic bonds
- branched = many end for hydrolysis

Question 10

describe the structure and functions of glycogen

Answer 10

1,4 and 1,6 glycosidic bonds
- branched = many end for hydrolysis
unsoluble = no osmotic effect and doesnt diffuse out of cells

Question 11

describe the structure and functions of cellulose

Answer 11

1,4 glycosidic bonds
- straight chain, unbranched molecule
- parallel strands

Question 12

describe Benedict test for reducing sugars

Answer 12

1. add an equal volume of Benedict reagent to a sample
2. heat. the mixture in an electric water bath at 100c for 5 minutes
3. positive result: colour change from blue to orange and brick red precipitate forms

Question 13

describe the Benedict test for non-reducing sugars

Answer 13

1. negative result: Benedict reagent remains blue
2. hydrolyse non-reducing sugars
3. neutralize the mixture using sodium carbonate solution
4. proceed with the Benedict test as usual

Question 14

describe the test for starch

Answer 14

1. add iodine solution
   positive result : colour change from orange to blue-black

Question 15

describe how to test for lipids in a sample

Answer 15

1. dissolve solid samples in ethanol
2. dd an equal volume of water and shake
3. positive result: milky white emulsion

Question 16

how do triglycerides form?

Answer 16

condensation reaction between 1 molecule of glycerol and 3 fatty acids to form an ester bond

Question 17

difference between saturated and
unsaturated fatty acids

Answer 17

unsaturated fatty acids have a double bond in the carbon chain.