1.4 Proteins ( biological molecules ) Flashcards
(10 cards)
1
Q
Describe / draw general structure of amino acid
A
C in the middle , R , H , COOH and H2N surrounded by C
2
Q
how many amino acids are common in all organisms how do they vary
A
20 amino acids that are common in all organisms different only in their side group (R)
3
Q
Describe how amino acids join together
A
- condensation reaction
- removing a water molecule
- between carboxyl / COOH group of one and amine / NH2 group of another
- forming a peptide bond
4
Q
what are dipeptides and polypeptides
A
- dipeptide => 2 amino acids joined together
- Polypeptide => many amino acids joined together
5
Q
describe the primary structure of a protein
A
- sequence of amino acids in a polypeptide chain , joined by peptide bonds
6
Q
describe the secondary structure of a protein
A
- folding of polypeptide chain e.g alpha helix / beta pleated sheets
- due to hydrogen bonding between amino acids
- between NH and C=O
7
Q
describe the tertiary structure of a protein
A
- 3D folding of polypeptide chain
- Due to interactions between amino acids R groups
- Forming hydrogen bonds , ionic bonds and disulfide bridges
8
Q
describe quaternary structure of protein
A
- more than one polypeptide chain
- formed by interactions between polypeptides
9
Q
describe the test for proteins
A
- add biuret reagent
- positive result = purple colour
10
Q
EQ : Describe how the structure of a protein depends on the amino acid it contains (5)
A
- structure is determined by position of amino acid
- primary structure is sequence / order of amino acids
- secondary structure formed by hydrogen bonding
- tertiary structure formed by interactions ( hydrogen , ionic , disulfide bridges )
- creates active site in enzymes
- quaternary structure contains > 1 polypeptide chain
