Proteins

Question 1

what are the monomers of proteins

Answer 1

Amino acids

Question 2

Role of proteins in the body

Answer 2

• work as a catalyst in cellular reactions enzymes

*play an important structural role in cell membrane
(Help with a human organism to repair damaged tissue)

• especially important in the body as they help with:
• structure
• growth
• maintenance
• repair of damaged tissue

Question 3

Role of proteins in the body pt2

Answer 3

• haemoglobin in the blood carries molecules in the cell membrane transport
• albumin in eggs and protein in meat nutrients
• insulin hormones
• movement actin and myosin in muscles
• antibodies protection against disease
• reserve source of energy

Question 4

Amino acids

Answer 4

20 naturally accruing amino acids

Bind by means of peptide bonds

Two amino acids form a dipeptide(condensation, water is lost)

Three form a tripepride

Four or more form a polypeptide

50 or more amino acids make a protein (full blown protein)

Question 5

Type of protein is determined by

Answer 5

1. Type of amino acid
2. Number of amino acids
3. Sequence of amino acid in the protein

Question 6

Dipeptide formation

Answer 6

Amino acids combine chemically by condensation forming dipeptides
Eg. Glycine + alanine —> dipeptide + H2O

Water is lost during the formation of dipeptide
The reaction is catalysed by enzymes

Question 7

Polymers formation

Answer 7

Formed by condensation synthesis
- for each monomer added to a molecule a water molecule is formed (taking water away)

Polymers are broken down into smaller units (monomers) 
By hydrolysis( water splitting) ( adding water)

Question 8

Polypeptides

Answer 8

Are polymers of more than two but less than fifty amino acids jointed together by peptide links.

Some polypeptides are metabolically active

Question 9

Protein configuration

Answer 9

Primary structure : is the linear sequence of amino acids linked together by peptide bonds. (String of beads)

Secondary structure : is formed when the linear structure folds/twists on itself forming a helix. Twist and folds are held in place by weak hydrogen bonds.

Tertiary structure : formed when the helix is coiled/folded to produce a compact ball like(globular) molecule. Held in place by very strong double sulphur bonds

Quaternary structure : a number of protein subunits joined together to become a functional.

Question 10

Properties of proteins

Answer 10

Proteins are usually macromolecules, made by linking at least 100 amino acids molecules

All proteins are insoluble in water

But some are hydrophilic (attract water)eg. Haemoglobin

And some are hydrophobic ( repel water) eg. Keratin(protein in skin and hair)

Question 11

Properties of proteins pt2

Answer 11

Globular proteins are denatured by heat and changes in pH. Eg. Enzymes and haemoglobin

If the temperature rises above normal of if the pH lates the proteins bromide denatured(descaled, deformed)

They lose their 3D shape as the hydrogen bonds break easily

As a result the enzymes will not be able to carry out their normal function

Very low temperatures can temporarily denature proteins

pH must remain at about 7.3 and if it doesn’t we will die.

Question 12

Sources Of protein

Answer 12

1. Legumes
   Eg. Peas, beans, soya beans
2. Meat, fish and eggs
3. Unrefined rice and wheat
4. Dairy products