2.2 Biological Molecules

Question 1

Name the elements in
-carbohydrates
-proteins
-lipids
-nucleic acids

Answer 1

-Carbohydrates - C, H, O
-Proteins - C, H, O, N, S
-Lipids - C, H, O
-Nucleic acids - C, H, O, N, P

Question 2

What are the properties of water?

Answer 2

-Ice is less dense than water
-Water is a solvent as it is polar so can dissolve solute
-High latent heat of vaporisation
-High specific heat capacity
-Cohesion and surface tension
-Liquid at room temperature

Question 3

Maltose is a disaccharide, what are the 2 monosaccharides it is made from?

Answer 3

-Alpha glucose + alpha glucose

Question 4

Sucrose is a disaccharide, what are the 2 monosaccharides it is made from?

Answer 4

-Fructose and alpha glucose

Question 5

Lactose is a disaccharide, what are the 2 monosaccharides it is made from?

Answer 5

-Beta galactose and alpha glucose

Question 6

Cellobiose is a disaccharide, what are the 2 monosaccharides it is made from?

Answer 6

-beta glucose + beta glucose

Question 7

What is the structure of amylose?

Answer 7

Long chain of alpha glucose. Contains only 1,4 glycosidic bonds as it is not branched. Coils into spiral shape

Question 8

What is the structure of amylopectin?

Answer 8

Long chain of alpha glucose. Contains 1,4 and 1,6 glycosidic bons as it is branched and coils

Question 9

What is the structure of glycogen?

Answer 9

Long chain of alpha glucose, Contains both 1,4 and 1,6 glycosidic bonds as it is branched. It is more branched than amylopectin so it is more compact

Question 10

What is the structure of cellulose?

Answer 10

It is made up of beta glucose molecules. Every other beta glucose is rotated 180 degrees so it forms straight chain. Hydrogen bonds hold the chains together and prevent it from coiling

Question 11

What is the structure of a triglyceride?

Answer 11

1 Glycogen bonded to 3 fatty acid tails by an ester bond. if it is saturated there are no C=C bonds

Question 12

What are the functions of triglycerides?

Answer 12

-Electrical and thermal insulation
-Protection
-Buoyancy
-Energy source and energy store

Question 13

What is the structure of phospholipids?

Answer 13

1 glycerol bonded to two fatty acids and one phosphate group

Question 14

What is the structure of an amino acid?

Answer 14

NH2-CHR-COOH

Question 15

What is the primary structure of a protein?

Answer 15

The specific sequence of amino acids found in a molecule

Question 16

What is the secondary structure of a protein?

Answer 16

The folding of a chain of amino acids into an alpha helix or beta pleated sheet due to hydrogen bonding

Question 17

What is the tertiary structure of a protein?

Answer 17

The specific 3D shape of a protein molecule, bonded together by hydrogen bonds, ionic bonds, disulphide bonds and hydrophobic / hydrophilic interactions

Question 18

What is the quaternary structure of a protein?

Answer 18

Two or more polypeptide chains that make up a protein, bonded by hydrogen bonds, ionic bonds, disulphide bonds and hydrophobic / hydrophilic interactions

Question 19

Give 3 examples of fibrous proteins and state their roles

Answer 19

-Keratin - strong molecule, found in nails, horns, scales, etc. Provides mechanical strength and is impermeable
-Elastin - Can stretch and recoil so found in skin, alveoli, blood vessels, etc
-Collagen - provides mechanical strength, found in artery walls, tendons, bones, etc

Question 20

Give 3 examples of globular proteins and state their functions

Answer 20

-Haemoglobin - carries oxygen, made up of 4 polypeptide chains and 4 haem groups
-Insulin - 2 polypeptide chains
-Pepsin - enzyme