Q-1. Most abundant collagen in body is
a) Type I
b) Type II
c) Type III
d) Type IV
Answer: Type I
Explanation:
Collagen Type I:
This is the most abundant collagen of the human body.
It contains two chains called alpha-1 and alpha-2.
It is present in skin, cornea, bone, tendon, blood vessels.
Q-2. Normal role of Micro-RNA is
a) Gene regulation
b) RNA splicing
c) Initiation of translation
d) DNA conformational change
Answer: Gene regulation
Explanation:
A micro-RNA is a small non-coding RNA molecule (containing about 22 nucleotides) which functions in RNA silencing and post-transcriptional regulation of gene expression.
Q-3. Slicing activity is a function of
a) m-RNA
b) sn-RNA
c) r-RNA
d) t-RNA
Answer: sn-RNA
Explanation:
Sn-RNAs are non-coding RNA molecules that are key for pre-mRNA splicing.
Each snRNA is complexed with at least seven sn-RNPs, forming an UsnRNP.
UsnRNP is involved in splicing the introns.
Q-4. Sanger’s reagent is
a) Dinitrobenzene
b) Dichlorobenzene
c) Tetra-nitrobenzene
d) Tetrachlorbenzene
Answer: Dinitrobenzene
Explanation:
Sanger’s reagent or di-nitro-fluoro-benzene or DNFB is a chemical used for polypeptide sequencing.
Q-5. In methemoglobin the iron is in
a) Ferric form
b) Ferrous form
c) Ferric and ferrous form
d) None
Answer: Ferric form
Explanation:
Oxidation of the heme component of hemoglobin to the ferric state forms methemoglobin, which cannot bind oxygen.
This oxidation may be caused by the action of certain drugs such as nitrates, or endogenous products such as reactive oxygen intermediates.
The Methemoglobinemia is characterized by chocolate cyanosis and chocolate colored blood.
Q-6. Vitamin needed for Acetyl Co-A carboxylase is
a) Thiamine
b) Riboflavin
c) Niacin
d) Biotin
Answer: Biotin
Explanation
Acetyl-CoA carboxylase contains biotin as its prosthetic group.
The two-step reaction is very similar to other biotin-dependent carboxylation reactions, such as those catalyzed by pyruvate carboxylase and Propionyl Co-A carboxylase.
The carboxyl group, derived from bicarbonate (HCO3), is first transferred to biotin in an ATP-dependent reaction.
The biotinyl group serves as a temporary carrier of C02, transferring it to acetyl-CoA in the second step to yield malonyl-CoA.
Q-7. Which vitamin in large doses decreases triglyceride and cholesterol?
a) Vit B1
b) Nicotinic acid
c) Vit B12
d) Riboflavin
Answer: Nicotinic acid
Explanation
Nicotinic acid reduces the production of triglycerides and VLDL (very low-density lipoprotein, which is converted to LDL in the blood).
This leads to decreased LDL (“bad”) cholesterol, increased HDL (“good”) cholesterol, and lowered triglycerides.
Q-8. At physiological pH, the most stable amino acid is:
a) Histidine
b) Lysine
c) Arginine
d) Leucine
Answer: Histidine
Explanation:
Histidine plays unique roles in enzymatic catalysis.
The pK of its imidazole proton permits it to function at neutral pH or physiological pH as either a base or an acid catalyst.
Q-9. Amino acids secreted in cystinuria are all except
a) Ornithine
b) Histidine
c) Arginine
d) Lysine
Answer: Histidine
Explanation:
Cystinuria is an autosomal-recessive defect in re-absorptive transport of cystine and the dibasic amino acids ornithine, arginine, and lysine from the luminal fluid of the renal proximal tubule and small intestine.
Calculi are frequently multiple and bilateral, and they often form stag-horns.
Urinalysis:
Cystine is one of the sulfur-containing amino acids; therefore, the urine may have the characteristic odor of rotten eggs.
Urinalysis may show typical hexagonal or benzene crystals, which are essentially pathognomonic of cystinuria.
Sodium cyanide–nitroprusside test:
This is a rapid, simple, and qualitative determination of cystine concentrations.
Cyanide converts cystine to cysteine. Nitroprusside then binds, causing a purple hue.
Proton nuclear magnetic resonance spectroscopy of urine:
It is a very powerful technique that allows multi-component analysis useful in both diagnosis and follow-up.
Q-10. Amber codon refers to
a) Mutant codon
b) Stop codon
c) Initiating codon
d) Codon for more than one amino acid
Answer: Stop codon
Explanation:
Translation starts with a chain initiation codon or start codon.
The most common start codon is AUG, which is read as methionine or, in bacteria, as formyl-methionine.
Stop codons are also called “termination” or “nonsense” codons. The three stop codons have been given names:
UAG: Amber
UGA: Opal
UAA: Ochre