Biochemistry module No. 1

1. The peptide bond:
2. has a partial double bond character
3. is charged but non polar
4. has cis conformation
5. can be easily destroyed by acids
6. keeps the integrity of proteins by hydrophobic interaction

2. Regarding elastin:

1. it is a tough protein with high tensile strength
2. it is rich in proline and lysine
3. it is soluble protein polymer
4. cannot regain its original length when stretched
5. mutation of tropoelastin gene leads to marfans syndrome

3. Which is incorrect about proline:

1. it contains imino group
2. it has uncharged polar group
3. important for fibrous structure of collagen
4. doesn’t participate in hydrogen bonds
5. its side chain has an even distribution of electrons

4. Which is incorrect about hasselbalch equation:

1. it describes the release of protons by weak acids
2. the stronger the acid  the smaller the pk
3. ph is equal to pk when A- is equal to HA
4. at acidic ph of the stomach, aspirin will be uncharged and easily absorbed
5. pulmonary obstruction causes increase in CO2 and cause ph to rise

5.a- helix is disrupted by all except:

1. imino group of praline
2. bulky side chain of tryptophan
3. charged amino acids
4. branched chains amino acids
5. non polar side chain of glycine

6. Regarding collagen synthesis which is incorrect
7. occurs in fibroblasts
8. prolyl and lysyl hydroxylases are required
9. formation of triple helix occurs intracellulary
10. cross-linkin occurs extracellulary
11. glycosylation occurs extracellulary

7.Regarding coenzymes which is incorrect:

1. are strictly required by all enzymes
2. are the non-protein part of holoenzymes
3. are organic compounds
4. are tightly bound to their enzymes
5. are derived from vitamins

8.Regarding enzyme inhibition:

1. competitive inhibition is associated with decrease in Vmax
2. non-competitive inhibition result in increase km
3. addition of [s] can overcome non-competitive inhibition
4. non-competitive inhibition binds with active site of the enzyme
5. competitive inhibition binds reversibly to the enzyme

9. Regarding velocity which is incorrect:
10. V increases with increase in T until a peak of V is reached
11. extreme ph may lead to denaturation of enzymes
12. decreased V at hight T reflects changes in ionization state of enzyme active site
13. when [s] is much less than km the V is proportional to [s]
14. V is directly proportional to enzyme concentration

10. Enzyme fatty acid oxidation are localized in :
11. all organelles of the cell
12. cytosol
13. mitochondria
14. nucleus
15. lysosomes

TRUE and FALSE

1. The causative agent of prion disease has a different primary structure than the non-infective type (F)
2. collagen is most abundant protein in the human body (T)
3. lysine is a negatively charged amino acid a physiologi ph (F)
4. hydrogen bonds enhance solubility of proteins in an aqueous solution (T)
5. pyruvate carboxylase is a ligase enzyme (T)