Proteins

Question 1

What do proteins contain?

Answer 1

• Carbon hydrogen oxygen and nitrogen always
• Many also contain sulphur and some: phosphorus

Question 2

General structure of amino acid?

Answer 2

NH2, CHR, COOH aka Amino group, R group (20 diff options) & Carboxylic acid group

Question 3

How do 2 amino acids join together to form a dipeptide?

Answer 3

• Condensation reaction
• Water is removed
• Peptide bond forms between OH of carboxyl and H of amine group

Question 4

What is a protein?

Answer 4

Polymer made up of the monomer amino acids
- can be made up of one polypeptide chain or a more (commonly many)

Question 5

What is formed when we join many amino acids together?

Answer 5

A polypeptide chain

Question 6

1. Primary structure?

Answer 6

Order/sequence of amino acids in the polypeptide chain

Question 7

2. Secondary structure?

Answer 7

• Weak H Bonds form between: slightly + H in N-H group of one amino acid & slightly - O in C=O Group of another amino acid (due to their polarity)…
• *This pulls polypeptide chain into either: Alpha Helix coil (most common) or Beta pleated sheets
• The way H bonds form determines shape - Both can be found in one polypeptide chain
• • H Bonds hold the Amino acid sequence in a secondary structure

Question 8

Tertiary structure?

Answer 8

• Further folding of secondary structure (polypeptide chain)
• I saw a unique 3D shape
• Held together by different bonds between the R Groups of amino acids
• Held in place by ionic, H & disulphide bonds (& hydrophobic interactions)…
• held tgt by diff bonds between R groups of amino acids

Question 9

The result of hydrophobic interactions?

Answer 9

• non polar groups mutually repel: water & other polar groups
• this results in: a net attraction of non-polar groups for e/o so…
• non-polar side chains of amino acids be on inside of globular protein
• outside of protein contains mainly polar groups

Question 10

Quaternary Structure?

Answer 10

Two or more different poly peptide chains bonded together
- held tgt by same 4 types of bonds as tertiary
- may also be non-protein groups w protein aka: prosthetic groups

Question 11

The importance of primary structure?

Answer 11

• if amino acids in sequence is diff - will cause the ionic, hydrogen & disulphide bonds to form in diff location so - diff 3D shape so - no longer function/diff function

Question 12

What are the 2 groups of proteins based on structure/shape?

Answer 12

1. Globular proteins:
   - form spherical/ball shape
   - w compact structure
   - carry out metabolic functions e.g. enzymes & haemoglobin
2. Fibrous proteins:
   - form long chains/strands which run parallel to e/o & linked by cross-bridges (so very strong/stable)
   - fibre-like & hv structural functions e.g. collagen