1A Proteins

Question 1

What are proteins made up of?

Answer 1

Amino acids

Question 2

What is a dipeptide?

Answer 2

2 AMINO ACIDS joined together with a PEPTIDE BOND

Question 3

What is a polypeptide?

Answer 3

> 2 AMINO ACIDS joined together with PEPTIDE BONDS

Question 4

What is the structure of amino acid molecules?

Answer 4

> CARBON at the centre
Contains a VARIABLE GROUP
Also has an AMINO GROUP, CARBOXYL GROUP and a HYDROGEN ATOM

Question 5

What part of the amino acids molecules do peptide bonds form between?

Answer 5

Between the CARBOXYL GROUP of one molecule and the AMINO GROUP of the other

Question 6

Describe the structure of proteins.

Answer 6

> PRIMARY - the SEQUENCE of amino acids in the polypeptide chain
SECONDARY - HYDROGEN BONDS form between the amino acids which forms an ALPHA HELIX shape of a BETA PLEASTED SHEET
TERTIARY - HYDROGEN and IONIC BONDS form as well as DISULFIDE BRIDGES which forms the chain’s FINAL 3D STRUCTURE
QUATERNARY - POLYPEPTIDE CHAINS assemble together and are held by bonds

Question 7

What are the four main functions of proteins?

Answer 7

1) ENZYMES - catalysts for the HYDROLYSIS of molecules
2) ANTIBPDIES - involved in the IMMUNE RESPONSE
3) TRANSPORT PROTEINS
4) STRUCTURE - Eg. Keratin and collagen

Question 8

Describe the biuret test for proteins.

Answer 8

> Add SODIUM HYDROXIDE SOLUTION to the sample so that it is ALKALINE
Add COPPER (II) SULFATE SOLUTION
If proteins are present, the solution will turn PURPLE