1.6 Proteins

Question 1

What chemical groups make up amino acids?

Answer 1

-Amino group (-NH2)
- Carboxyl group (-COOH)
- Hydrogen atom (-H)
- R group (20 naturally occurring ones)

Question 2

In a condensation reaction with amino acids, how is it done and what bond does it form.

Answer 2

The water is removed by the -OH in the carboxyl group and the -H from the amine group
When linked it forms a PEPTIDE bond

Question 3

What is the primary structure of proteins?

Answer 3

sequence of amino acids being polymerised to form a polypeptide

Question 4

What is the secondary structure of proteins?

Answer 4

the hydrogen bonds allow it to be coiled into an ‘alpha-helix’

Question 5

What is the tertiary structure of proteins?

Answer 5

the A-helicase can be twisted and folded even more to give the complex 3D structure.
- disulfide bridges (fairly strong)
- ionic bonds
- hydrogen bonds

Question 6

What is the quaternary structure of proteins?

Answer 6

When more than 1 polypeptide chain is linked to another.
Contains an inorganic component (prosthetic group)

Question 7

What do 2 amino acids form?

Answer 7

Dipeptide

Question 8

What are the two types of proteins, list an example with both.

Answer 8

Globular - enzymes, haemoglobin
Fibrous - collagen (skin), keratin (hair)

Question 9

How do you test for proteins?

Answer 9

1) Place sample in test tube and add equal volume of sodium hydroxide solution at room temp.
2) Add few drops of very dilute copper(II) sulfate solution and mix gently
3) a blue-purple colouration indicates the presence of peptide bonds, hence a protein