properties of proteins

Question 1

functions of proteins in the body

Answer 1

• structural proteins eg. keratin and collagen
• Enzymes, speed up chemical reactions
• hormones, eg. insulin
• haemoglobin, transports O2 in the blood
• antibodies
• channel and carrier proteins

Question 2

structure of monomers

Answer 2

• contain the elements carbon, oxygen, hydrogen, nitrogen and sometimes nitrogen
• the monomers of proteins are amino acids

Question 3

whats the general structure of an amino acid

Answer 3

variable group
R
H | OH
> N - C - C ≤
H | O
N
amine carboxyl

Question 4

structure of polymers (polysaccharides)

Answer 4

1. primary structure
2. secondary structure
3. tertiary structure
4. quaternary structure

Question 5

describe the primary structure

Answer 5

the sequence of amino acids in the polypeptide chain, joined by peptide bonds

Question 6

describe the secondary structure

Answer 6

coiling and folding of the polypeptide chain held together by hydrogen bonds

Question 7

what are the two forms of secondary structure?

Answer 7

• alpha helix (coiling)
• beta pleated sheet

Question 8

describe the tertiary structure

Answer 8

more folding or twisting to create a compact globular or fibrous structure with the R groups on the amino acids
held together by the bonds:
- hydrogen
- ionic
- disulphide

Question 9

describe the quaternary structure

Answer 9

more than one polypeptide chain joined together

Question 10

what are the two types of protein shapes, and an example of each?

Answer 10

• globular, compact ball shaped structure
  Eg. membrane (channel and carrier proteins)
• fibrous, long, thin and rope-like
  Eg. Keratin

Question 11

whats the test for proteins?

Answer 11

biuret test
add biuret reagent and shake
protein present: solution turns from blue to purple
no protein: solution remains blue