Q-31. In a DNA, the coding region reads 5-CGT-3 in coding strand. This would code in the RNA as
a) 5-CGU-3
b) 5-GCA-3
c) 5-ACG-3
d) 5-UGC-3
Answer: 5-CGU-3
Explanation:
The strand that is transcribed or copied into an RNA molecule is referred to as the template strand of the DNA.
The other DNA strand, non template strand is frequently referred to as the coding strand of that gene.
It is called this because with the exception of T for U changes, it corresponds exactly to the sequence of the RNA primary transcript.
Q-32. RBC membrane is maintained by
a) Spectrin
b) Laminin
c) Collagen
d) Elastin
Answer: Spectrin
Explanation:
The shape, flexibility and the strength of RBC membrane is maintained by:
Spectrin (Most important)
Ankyrin
Protein 4.1
The deficiency of any one of the membrane skeletal proteins can cause hereditary spherocytosis.
Q-33. In synthesis of fatty acids, energy is supplied by
a) NAD
b) FAD
c) GTP
d) NADPH
Answer: NADPH
Explanation:
In humans, fatty acid synthesis occurs primarily in the liver and lactating mammary glands and to lesser extent, in adipose tissue.
The process incorporates carbons from acetyl Co-A into the growing fatty acid chain, using ATP and NADPH.
The HMP is the major supplier of NADPH for fatty acid synthesis.
Q-34. Which of these amino acids does not have anomeric carbon atom?
a) Valine
b) Alanine
c) Tyrosine
d) Glycine
Answer: Glycine
Explanation:
With the sole exception of glycine, the alfa-carbon of amino acids is chiral. Glycine lacks anomeric carbon.
Although some protein amino acids are dextrorotatory and some levorotatory, all share the absolute configuration of L-glyceraldehyde and thus are L-α-amino acids.
Several free L-α amio-acid fulfill important roles in metabolic processes. Examples include ornithine, citrulline, and arginine-succinate that participate in urea synthesis; tyrosine in formation of thyroid hormones; and glutamate in neurotransmitter biosynthesis.
D-Amino acids that occur naturally include free D-serine and D-Aspartate in brain tissue, D-alanine and D-glutamate in the cell walls of gram-positive bacteria, and D-amino acids in certain peptides and antibiotics produced by bacteria, fungi, reptiles and other non-mammalian species.
Q-35. In hemoglobin the innate affinity of heme for carbon monoxide is diminished by the presence of:
a) His F9
b) His E7
c) Gly B6
d) Thr C4
Answer: His E7
Explanation:
The heme of Myoglobin lies in a crevice between helices E and F oriented with its polar propionate groups facing the surface of the globin. The remainder resides in the non-polar interior.
The fifth co-ordination position of the iron is linked to ring nitrogen of a proximal histidine, His F8.
The distal histidine, His E7, lies on the side of the heme ring opposite to His F8.
The innate affinity of heme for carbon monoxide is diminished by the presence of His E7. His E7 creates a hindering environment for CO by disturbing the orientation of atoms in the heme molecule.
Q-36. An alfa helix of a protein is most likely to be disrupted if a missense mutation introduces the following amino acid within the alpha helical structure?
a) Alanine
b) Aspartic acid
c) Tyrosine
d) Glycine
Answer: Glycine and Aspartic acid
Explanation:
Alfa helix of a protein can be disrupted due to the introduction of the following amino acids:
Proline: The imino group of proline is not geometrically compatible with the right handed spiral of the alpha-helix
Proline can only be stably accommodated within the first turn of an alfa helix. When present elsewhere, proline disrupts the conformation of the helix, producing a bend. Because of its small size, glycine also often induces bends in alfa helix.
Charged amino acids: Glutamate, aspartate, lysine, arginine and histidine
Amino acids with bulky side chains: tryptophan
Amino acids that branch at the beta-carbon: Valine and iso-Leucine.
Q-37. One of the following enzymes is not a protein:
a) DNAase
b) Abzyme
c) Eco RI
d) Ribozyme
Answer: Ribozyme
Explanation:
An Abzyme is a monoclonal antibody with catalytic activity.
Ribozymes are RNA molecules with catalytic activity. These generally involve trans-esterification reactions, and most are concerned with RNA metabolism (Splicing and endo-ribonuclease)
Ribozyme also performs the peptidyl transferase activity.
Q-38. During gluconeogenesis reducing equivalents from mitochondria to the cytosol are transported by:
a) Malate
b) Aspartate
c) Glutamate
d) Oxalo-acetate
Answer: Malate
Explanation:
Oxalo-acetate formed in mitochondria must enter the cytosol where the other enzymes of gluconeogenesis are located.
OAA is unable to directly cross the inner mitochondrial membrane; it must first be reduced to Malate by mitochondrial Malate dehydrogenase.
OAA + (NADH + H+) > Malate + NAD+
Malate can be transported from mitochondria to the cytosol, where it is re-oxidized to OAA by cytosolic Malate dehydrogenase.
Malate + NAD+> OAA + (NADH + H+)
Q-39. The following separation technique depends on the molecular size of the protein:
a) Chromatography on a carboxy-methyl (CM) cellulose column
b) Iso-electric focusing
c) Get filtration chromatography
d) Chromatography on a di-ethyl-amino-ethyl (DEAE) cellulose column
Answer: Get filtration chromatography
Explanation:
Get filtration chromatography OR Size-exclusion chromatography (SEC):
Gel filtration (GF) chromatography separates proteins solely on the basis of molecular size.
Separation is achieved using a porous matrix to which the molecules, for steric reasons, have different degrees of access–i.e., smaller molecules have greater access and larger molecules are excluded from the matrix. Hence, proteins are eluted from the GF column in decreasing order of size.
Q-40. At the physiological pH, the DNA molecules are:
a) Positively charged
b) Negatively charged
c) Neutral
d) Amphipathic
Answer: Negatively charged
Explanation:
For all forms of DNA the global structure has an overall negative charge and the overall electrostatic potential is negative.
This is largely due to the phosphate groups of DNA which bear an overall negative charge due to the negatively charged oxygen atoms they have.
However, DNA has both positive and negative charges covering its outer structure. The charge dispersion over the global structure of DNA varies between A-DNA, B-DNA, and Z-DNA.
B-DNA has mostly negative electrostatic potential spread throughout its global exterior and concentrated mostly in major and minor grooves.