Q-21. Northern blot test is used for
a) DNA analysis
b) RNA analysis
c) Analysis of proteins
d) Enzyme analysis
Answer: RNA analysis
Explanation:
Northern blot– RNA analysis
Southern blot– DNA analysis
Western blot– Analysis of proteins
Q-22. In a mutation if valine is replaced by which of the following would not result in any change in function of protein (hemoglobin)
a) Proline
b) Glycine
c) Aspartic acid
d) Leucine
Answer: Aspartic acid
Explanation:
The codon for valine at position 67 of the beta chain of hemoglobin is not identical in all persons who possess a normal functional beta chain of hemoglobin.
Hemoglobin Milwaukee has at position 67 a Glutamic acid: hemoglobin Bristol contains aspartic acid at position 67. Hemoglobin Sydney contains alanine at position 67.
Q-23. A mutation in the codon, which causes a change in the amino acid being coded, is referred to as
a) Missense mutation
b) Recombination
c) Somatic mutation
d) Mitogenesis
Answer: Missense mutation
Explanation:
Point mutation:
A missense mutation is a point mutation in which a single nucleotide change results in a codon those codes for a different amino acid.
Missense mutations can render the resulting protein nonfunctional, and such mutations are responsible for diseases such as Epidermolysis bullosa, sickle-cell disease etc.
A nonsense mutation converts an amino acid codon into a termination codon. This causes the protein to be shortened because of the stop codon interrupting its normal code.
Silent mutations: Code for the same amino acid. A silent mutation has no effect on the functioning of the protein.
Q-24. In a patient with starvation for 72 hours which of the following would be seen?
a) Increased ketosis due to breakdown of fats
b) Increased gluconeogenesis by muscle protein breakdown
c) Increased Glycogenolysis
d) Increased gluconeogenesis
Answer: Increased ketosis due to breakdown of fats
Explanation:
During starvation, the metabolic changes providing energy can be divided into three stages:
First stage:
It lasts first 2 to 3 days.
Glycogenolysis (Liver glycogen is the first stored food that is mobilized for energy production.)
Gluconeogenesis- From alanine, glycerol, lactate
Second stage:
It lasts for over 2 weeks.
Fat is mobilized with ketosis and ketonuria.
Third stage:
Tissue protein is degraded for energy production.
Q-25. Which of the following membranes would be having highest protein content per gram tissue?
a) Inner mitochondrial membrane
b) Outer mitochondrial membrane
c) Plasma membrane
d) Myelin sheath
Answer: Inner mitochondrial membrane
Explanation:
Ratio of protein to lipid in different membranes:
Inner mitochondrial membrane- 3.2
Sarcoplasmic reticulum- 2.0
Outer mitochondrial membrane-1.1
Myelin sheath-0.23
Q-26. The presence of lone pair on the oxygen in water molecule results in
a) Makes water non-polar solvent
b) Electro positive charge on water molecule
c) Electro negative charge on water molecule
d) Covalent bond in ice
Answer: Electro negative charge on water molecule
Explanation:
In water, each hydrogen nucleus is covalently bound to the central oxygen atom by a pair of electrons that are shared between them. In H2O, only two of the six outer-shell electrons of oxygen are used for this purpose, leaving four electrons which are organized into two non-bonding pairs.
Because the two non-bonding pairs remain closer to the oxygen atom, these exert a stronger repulsion against the two covalent bonding pairs, effectively pushing the two hydrogen atoms closer together. The result is a distorted tetrahedral arrangement.
The H2O molecule is electrically neutral, but the positive and negative charges are not distributed uniformly.
Q-27. Defect in folding proteins would result in a clinical disease in which of the following
a) Myopia
b) Hypothyroidism
c) Migraine
d) Kuru
Answer: Kuru
Explanation:
The term “prions” refers to abnormal, pathogenic agents that are transmissible and are able to induce abnormal folding of specific normal cellular proteins called prion proteins that are found most abundantly in the brain.
Prion diseases are usually rapidly progressive and always fatal.
Human Prion Diseases:
Creutzfeldt – Jakob disease (CJD)
Variant Creutzfeldt – Jakob disease (vCJD)
Gerstmann-Sträussler-Scheinker Syndrome
Fatal Familial Insomnia
Kuru
Animal Prion Diseases:
Bovine Spongiform Encephalopathy (BSE)
Chronic Wasting Disease (CWD)
Scrapie
Transmissible mink encephalopathy
Feline spongiform encephalopathy
Ungulate spongiform encephalopathy
Q-28. Which of the following dose not cross cell membrane easily?
a) Glucose
b) Glucose 6 phosphate
c) Nitric oxide
d) Carbon monoxide
Answer: Glucose 6 phosphate
Explanation:
When digestion of a meal is complete, insulin levels fall, and enzyme systems in the liver cells begin to remove glucose molecules from strands of glycogen in the form of G6P. This process is termed glycogenolysis.
The G6P remains within the liver cell unless the phosphate is cleaved by glucose-6-phosphatase.
This de-phosphorylation reaction produces free glucose and free PO4 anions.
The free glucose molecules can be transported out of the liver cells into the blood to maintain an adequate supply of glucose to the brain and other organs of the body.
Q-29. Viscosity in synovial fluid depends upon
a) N-acetyl galactosamine
b) N-acetyl glucosamine
c) Hyaluronic acid
d) Glucuronic acid
Answer: Hyaluronic acid
Explanation:
Normal synovial fluid contains hyaluronan (hyaluronic acid), a polymer of disaccharides composed of D-glucuronic acid and D-N-acetyl glucosamine joined by glycosidic bonds.
Hyaluronan is synthesized by the synovial membrane and secreted into the joint cavity to increase the viscosity and elasticity of articular cartilages and to lubricate the surfaces between synovium and cartilage.
Hyaluronic acid is especially high in concentration in embryonic tissue and is thought to play an important role in permitting cell migration during morphogenesis and wound repair.
The high concentration of hyaluronic acid and chondroitin sulfates present in cartilage contribute to its compressibility.
Q-30. All of the following are extracellular proteins except
a) Laminin
b) Integrin
c) Collagen
d) Fibronectin
Answer: Integrin
Explanation:
Integrins are the part of the cell membrane that mediates cellular attachment to extracellular matrix.
Extra-cellular matrix:
Fibrous structural proteins-Collagen and Elastin
Adhesive glyco-proteins- Fibronectin and Laminin
Ptroteo-glycans and hyaluronan