Biological Molecules

Question 1

What are monomers?

Answer 1

-Small, basic molecular units that can form a polymer

Question 2

What are polymers?

Answer 2

-Large, complex molecules composed of long chains of monomers joined together during a condensation reaction

Question 3

Name three monosaccharides

Answer 3

-Glucose
-Fructose
-Galactose

Question 4

Describe the difference between alpha glucose and beta glucose

Answer 4

-H and OH groups on right hand side are swapped
-Alpha glucose=H on top, OH below
-Beta glucose=H below, OH on top

Question 5

What bond forms between two monosaccharides when they are joined together?

Answer 5

-Glycosidic bond

Question 6

What two monosaccharides is sucrose made of?

Answer 6

-Glucose
-Fructose

Question 7

What two monosaccharides is maltose made of?

Answer 7

-Glucose
-Glucose

Question 8

What two monosaccharides is lactose made of?

Answer 8

-Glucose
-Galactose

Question 9

How do you test for reducing sugars?

Answer 9

-Heat sample with Benedict’s solution
-Green/yellow/orange/red precipitate=positive

Question 10

How do you test for a non-reducing sugar?

Answer 10

-Heat sample with Benedict’s solution
-Stays blue
-Add dilute hydrochloric acid
-Neutralise with sodium hydrogencarbonate
-Heat sample with Benedict’s solution
-Green/yellow/orange/red ppt=positive

Question 11

Describe the structure of starch

Answer 11

-Amylose=long, unbranched, alpha-glucose, coiled, compact
-Amylopectin=long, branched, alpha-glucose, enzymes easily reach branches, glucose quickly released
-Insoluble in water

Question 12

Describe the structure of glycogen

Answer 12

-Alpha-glucose
-Branched=stored glucose quickly released
-Compact

Question 13

Describe the structure of cellulose

Answer 13

-Long
-Unbranched
-Beta-glucose
-Chains linked together by H bonds=form microfibrils

Question 14

How do you test for starch?

Answer 14

-Iodine solution
-Blue-black=positive

Question 15

Describe the structure of triglycerides

Answer 15

-Glycerol
-3 fatty acid tails=hydrophobic

Question 16

What is a saturated fatty acid?

Answer 16

-Doesn’t have any double bonds between carbon atoms

Question 17

What is an unsaturated fatty acid?

Answer 17

-Double bonds between carbon atoms, causes the chain to kink

Question 18

What bond forms between a glycerol molecule and a fatty acid?

Answer 18

-Ester bond

Question 19

What are the properties of a triglyceride?

Answer 19

-Hydrocarbon tails of fatty acids contain lots of chemical energy
-Insoluble in water, don’t affect water potential

Question 20

What are the properties of a phospholipid?

Answer 20

-Heads are hydrophilic
-Tails are hydrophobic
-Form a bilayer
-Water-soluble substances can’t pass through

Question 21

How do you test for lipids?

Answer 21

-Emulsion test
-Add ice cold ethanol
-Shake
-Add water
-Milky emulsion-positive

Question 22

What is the structure of an amino acid?

Answer 22

R
|
H2N-C-COOH
|
H

Question 23

What bond forms when amino acids are joined together?

Answer 23

-Peptide bond

Question 24

Describe the primary structure of a protein

Answer 24

-The sequence of amino acids in a polypeptide chain

Question 25

Describe the secondary structure of a protein

Answer 25

-H bonds form between amino acids in the chain -Alpha helix shape or beta pleated sheet

Question 26

Describe the tertiary structure of a protein

Answer 26

-Folded again -Hydrogen bonds, ionic bonds and disulphide bridges form -3D structure

Question 27

Describe the quaternary structure of a protein

Answer 27

-Multiple polypeptide chains held together by bonds -3D globular structure

Question 28

How do you test for proteins?

Answer 28

-Add sodium hydroxide solution -Add copper(II) solution -Purple=positive

Question 29

Describe the induced fit model

Answer 29

-Active site and substrate not entirely complementary -Enzyme moulds around substrate to form an enzyme-substrate complex

Question 30

What is a competitive inhibitor?

Answer 30

-Complementary to shape of active site -Binds with enzyme before substrate can -No enzyme-substrate complex can form

Question 31

What is a non-competitive inhibitor?

Answer 31

-Binds to enzyme away from active site -Changes shape of active site -Substrate no longer complementary -Can't form an enzyme-substrate complex