Topic 1 : Biological Molecules

Question 1

Define monomer

Answer 1

Smaller repeating units which form larger moleules

Question 2

Define polymers

Answer 2

Larger molecules made from many identical molecules

Question 3

What happens in a condensation reaction?

Answer 3

2 molecules join together, forming a chemical bond and releasing a water molecule

Question 4

What happens is a hydrolysis reaction?

Answer 4

2 molecules are separated, breaking the chemical bond and using a water molecule

Question 5

Give 3 examples of polymers and the monomers they’re made from

Answer 5

Polymer Monomer

Nucleotide Polynucleotide
Monosaccharide (glucose) Polysaccharide
Amino acid Polypeptide (protein)

Question 6

What are monosaccharides?

Answer 6

Monomers from which larger carbohydrates are made

Question 7

3 examples of carbohydrates

Answer 7

Glucose
Fructose
Galactose

Question 8

Describe the difference between the structure of alpha-glucose and beta-glucose

Answer 8

They have the same molecular formula but different atom arrangements

Alpha-glucose –> OH group is below carbon 1

Beta-glucose –> OH group is above carbon 1

Question 9

What are disaccharides and how are they formed?

Answer 9

Two monosaccharides joined by glycosidic bonds, formed by condensation reaction, releasing a water molecule

Question 10

List 3 disaccharides and the monosaccharides which they’re made from

Answer 10

Monosaccharides –> Disaccharide

Glucose + Glucose –> Maltose

Sucrose + Fructose –> Sucrose

Glucose + Galactose –> Lactose

Question 11

What are polysaccharides?

Answer 11

Many monosaccharide joined together with glycosidic bonds

Question 12

How are polysaccharides formed?

Answer 12

By many condensation reactions, releasing many water molecules

Question 13

Describe the function of starch

Answer 13

Energy store in plant cells

Question 14

Describe the function of glycogen

Answer 14

Energy store in animal cells

Question 15

Describe the function of cellulose

Answer 15

Provide strength and structural support to plant / algae cell walls

Question 16

Describe the structure of starch

Answer 16

Polysaccharide of alpha-glucose molecules

Amylose –> 1,4-glycosidic bonds –> unbranded

Amylopectin –> 1,4 and 1,6-glycosidic bonds –> branched

Question 17

What glycosidic bond causes a branched structure?

Answer 17

1,6-glycosidic

Question 18

What glycosidic bond causes an unbranched structure?

Answer 18

1,4-glycosidic

Question 19

Describe the structure of glycogen

Answer 19

Polysaccharide of alpha-glucose

1,4 and 1,6-glycosidic bonds –> branched

Question 20

Describe the structure of cellulose

Answer 20

Polysaccharide of beta-glucose

1,4-glycosidic bonds form straight, unbranched chains

These chains are linked in parallel to hydrogen bonds, forming microfibrils

Question 21

How does the structure of starch relate to its function?

Answer 21

Amylose:

Helical –> compacts for storage in cell

Large –> can’t leave cell through cell membrane

Insoluble in water –> water potential of cell is not affected

Question 22

How does the structure of glycogen relate to its function? (Also applies to amylopectin in starch)

Answer 22

Branched –> compact to fit more molecules in a small area

Branched –> more ends for faster hydrolysis –> release glucose for respiration to make ATP for energy release

Large –> can’t leave cell through cell membrane

Insoluble in water –> Water potential of cell not affected

Question 23

How does the structure of cellulose relate to is function?

Answer 23

Every other B-glucose molecule in inverted in a long, straight, unbranched chain

Many H bonds link parallel strands to form microfibrils

H bonds are strong in high numbers –> provides strength to plant cell walls