Proteins

Question 1

What is the primary structure of proteins?

Answer 1

The sequence of amino acids in a polypeptide chain

Question 2

What is the secondary structure of a protein?

Answer 2

The way the polypeptide chain folds or coils is called the secondary structure

Question 3

What does the secondary structure of a proteins depend on?

Answer 3

Hydrogen bonding

Question 4

What is the tertiary structure of a protein?

Answer 4

It is the further folding of the chain where more bonds form between different parts of the polypeptide chain.
It forms a 3D structure

Question 5

What is the quartenary structure of a protein?

Answer 5

This is the cross-linking of two or more polypeptide chains

Question 6

What is the tertiary structure responsible for?

Answer 6

It is responsible for the shape of active site in enzymes and the shape of channels in channel proteins

Question 7

What are the properties of a globular protein?

Answer 7

Molecules are ball shaped

Soluble

Hydrophobic R groups point to centre
Hydrophilic R groups point outwards

Question 8

Give 3 examples of globular proteins

Answer 8

Haemoglobin

Insulin

Amylase

Question 9

What is a conjugated protein?

Answer 9

This is where part of the molecule is not a protein and consists of a prosthetic group.

Question 10

What is the function and properties of haemoglobin?

Answer 10

It carries oxygen around the body in red blood cells

It is a conjugated protein

Each of the four polypeptide chains in haemoglobin has a prosthetic group called haem.

Haem contains iron which is what oxygen binds to.

Question 11

What is the function and properties of insulin?

Answer 11

It is a hormone secreted by the pancreas

Helps regulate blood glucose levels

It is soluble which means it can be transported in the blood to the tissues where it acts

Consists of two polypeptide chains held together by disulfide bonds

Question 12

What is the function and properties of amylase?

Answer 12

It is an enzyme that catalyses the breakdown of starch in the digestive system

Made of a single chain of amino acids

Contains both alpha helix and beta pleated sheet sections

Question 13

What are the properties of fibrous proteins?

Answer 13

Long strands

Usually insoluble

Structural

Question 14

Give three examples of fibrous proteins

Answer 14

Keratin

Collagen

Elastin

Question 15

What is the function and properties of collagen?

Answer 15

Found in animal connective tissues such as skin and bones

Very strong molecule

Minerals can bind to the protein to increase its rigidity

Question 16

What is the function and properties of keratin?

Answer 16

Found in external structures such as hair, skin, nails and feathers

Can be flexible-as in skin

Or hard and tough- as in nails

Question 17

What is the function and properties of elastin?

Answer 17

Found in elastic connective tissues such as skin, large blood vessels and some ligaments

It is elastic, so it allows tissues to return to their original after they have been stretched

Question 18

What are proteins?

Answer 18

Proteins are substances made from amino acids linked together by peptide bonds