AIIMS May 2011- Biochemistry

26. Which of the following is not degraded by colonic flora?

a. Pectin 
b. Lignin
c. Starch
d. Glucose


27. CAP in LAC operon is 

a. Positive regulator
b. Negative regulator
c. Attenuation
d. Constitutive expression


28. Following modification occurs in Gs subunit which leads to watery diarrhea in cholera:

a. ADP ribosylation
b. ATP-ADP transfer
c. Phosphorylation
d. Dephosphorylation


29. Apo B-48 and Apo B-100 is synthesized from the same mRNA; the difference between them is due to :

a. RNA splicing
b. Allelic exclusion
c. Deamination of cytidine to uridine
d. Upstream repression


30. Among the following, all are hydrophilic hormones that act on cytosolic receptors except one which is a lipophilic hormone that acts on nuclear receptor:

a. Thyroxine
b. Epinephrine
c. GH
d. ACTH


31. Gene duplication plays an important role in the evolution of:

a. mRNA
b. rRNA
c. tRNA
d. hn RNA


32. Movement of protein from nucleus to cytoplasm can be seen by:

a. FISH
b. FRAP
C. Confocal microscopy
d. Electron microscopy


33. Histone acetylation causes:

a. Increased heterochromatin formation
b. Increased euchromatin formation
c. Methylation of cystine
d. DNA replication


34. Triplex DNA is due to :

a. Hoogsteen pairing
b. Palindromic sequences
c. Large no. of guanosine repeats
d. Polypyramidine tracts


35. Acetyl Coa can be directly converted to all except:

a. Glucose
b. Fatty acids
c. Cholesterol
d. Ketone bodies


36. After digestion by restriction endonucleases, DNA strands can be joined again by:

a. DNA polymerase
b. DNA ligase
c. DNA topoisomerase
d. DNA gyrase


37. True about sickle cell disease are all except:

a. Single nucleotide change results in glutamine to valine.
b. Sticky patch is generated as a result of replacement of a non-polar residue with a polar residue.
c. HbS confers resistance against malaria in heterozygotes.
d. RFLP results from a single base change.