Proteins

Question 1

Describe the basic structure of amino acids.

Answer 1

Carboxyl group, side chain, and amino group.

Question 2

Describe the classification of amino acids with reference to the characteristics of the amino acid side chains

Answer 2

Hydrophobic or hydrophilic.
Hydrophilic can be further separated to neutral, basic, and acidic

Question 3

Describe the primary, secondary, tertiary and quaternary structure of proteins.

Answer 3

Primary: polypeptide chain, n terminus to c terminus
secondary: alpha helices and beta pleated sheets
tertiary: folding into globular form, still depends on aa sequence
Quaternary: 2 or more polypeptide chains held together by non-covalent interactions or interchain disulphide bonds

Question 4

Explain the concept of ‘native conformation’ of a protein.

Answer 4

The folding of a protein as it is found in its natural, functional state

Question 5

Describe the basic characteristics of globular and fibrous proteins.

Answer 5

Globular: compact folded structure, hydrophobic aa’s inside, hydrophilic aa’s outside
Fibrous: regular, secondary structural elements of specific amino acids

Question 6

Describe post-translational modifications of proteins and their impact on protein function.

Answer 6

Functional group attached to amino acid, resulting in change in protein function. phosphrylation, gylcosylation, acylation, ubiquitination (death signal), nitrosylation

Question 7

Discuss post-translational modification disorders. An example given is Congenital Disorders of Glycosylation (CDG).

Answer 7

CDG: deficiency of enzymes in oligosaccharide synthetic pathway, causing a defect in N-linked protein glycosylation. complex presentation with chronic diarrhea, coagulation defects, liver fibrosis, abnormal skeletal development