biochemistry of proteins

Question 1

define dipeptide

Answer 1

A dipeptide is an organic compound derived from 2 amino acids joined by peptide bonds

Question 2

define polypeptide

Answer 2

a chain of many amino acids joined by peptide bonds

Question 3

describe the role that water plays in the production and breakdown of dipeptides

Answer 3

in the production of dipeptides water is released due to condensation reactions and in the breakdown of dipeptides water is used in hydrolysis

Question 4

Many amino acids joined together in a polypeptide chain is referred to as the primary structure of a protein

a. Describe how the primary structure then forms the secondary structure of a protein

Answer 4

the sequence of amino acids in the polypeptide chain is the primary structure of the protein, interactions between the amino acids in the polypeptide chain cause the chain to twist into a 3 D shape.

Lengths of the chain may coil into alpha helices or come together into beta-pleated sheets - these features are known as the secondary structure

Question 5

b. Describe how the secondary structure then forms the tertiary structure

Answer 5

the polypeptide chain folds further to produce a precise final 3D shape

Question 6

c. Define the term: quaternary structure

Answer 6

several polypeptide chains held together

Question 7

d. Define the term: conjugated protein

Answer 7

proteins that have another chemical group associated with their polypeptide chains

Question 8

Compare and contrast the structure and properties of fibrous and globular proteins

Answer 8

globular:
-polypeptide chain folded into a compact spherical shape
- have hydrophillic side chains that project from the side of the molecule
-3D shape
fibrous:
-fibrous proteins dont fold into a ball but remain as long chains
-insoluble
-3 polypeptide chains wind around each other to form a rope like strand held together by H bonds
-several polypeptide chains can be cross linked