Q-191. Within the RBC, hypoxia stimulates glycolysis by which of the following regulating pathways
a) Hypoxia stimulates pyruvate dehydrogenase by increased 2, 3 DPG
b) Hypoxia inhibits hexokinase
c) Hypoxia stimulates release of all glycolytic enzymes from band 3 on RBC membrane
d) Activation of the regulatory enzymes by high pH
Answer: Hypoxia stimulates release of all glycolytic enzymes from band 3 on RBC membrane
Explanation:
Hypoxia-> Deoxygenation of hemoglobin-> Increases band-3 tyrosine phosphorylation-> Release of all glycolytic enzymes from band-3 on RBC membrane-> Stimulates glycolysis
Q-192. Regarding synthesis of tri-acyl glycerol in adipose tissue, all of the following are true except
a) Synthesis from di-hydroxy-acetone phosphate
b) Enzyme glycerol kinase plays an important role
c) Enzyme glycerol 3 phosphate dehydrogenase plays an important role
d) Phosphatidate is hydrolyzed
Answer: Enzyme glycerol kinase plays an important role
Explanation:
In adipose tissue, the enzyme glycerol kinase is not expressed and glycerol cannot be utilized for the provision of glycerol-3-phosphate which must be supplied by glucose via glycolysis.
Di-hydroxy-acetone phosphate provides glycerol 3 phosphate for synthesis of triacylglycerol in adipose tissues.
Enzyme glycerol-3-phosphate dehydrogenase is required to obtain the precursor glycerol-3-phosphate from Di-hydroxy-acetone phosphate.
Q-193. Same amino acid is coded by multiple codons d/t following
a) Degeneracy
b) Frame – Shift mutation
c) Mutation
d) Transcription
Answer: Degeneracy
Explanation:
The genetic code is redundant or degenerate. Although each codon corresponds to a single amino acid, a given amino acid may have more than one codon for it.
For example, arginine is specified by six different codons.
Q-194. Agranular endoplasmic reticulum takes part in synthesis of
a) Lipids
b) Proteins
c) Carbohydrates
d) Vitamins
Answer: Lipids
Explanation:
Agranular reticulum:
It is characterized by the absence of ribosomes due to which its walls are smooth.
This Agranular reticulum is most common in those cells which are concerned with steroid or lipid synthesis.
Q-195. Muco-polysaccharide hyaluronic acid occurs maximally at
a) Lens
b) Vitreous humor
c) Retina
d) Cornea
Answer: Vitreous humor
Explanation:
Distribution of various Glycosaminoglycans:
Hyaluronic acid- Synovial fluid, vitreous humor, loose connective tissue
Chondroitin sulfate- Cartilage, bone, cornea
Keratan sulfate I- Cornea
Keratan sulfate II- Loose connective tissue
Q-196. Sample for blood glucose estimation preserved while sending it from PHC to Civil Hospital
a) Sodium fluoride
b) Citrate
c) EDTA
d) Heparin
Answer: Sodium fluoride
Explanation:
Fluoride inhibits glycolysis by inhibiting enolase; this will help in correct determination of the glucose level as glycolysis will not be able to affect the level of glucose.
Q-197. Increased level of apo-lipoprotein A predisposes to
a) Nephrotic syndrome
b) Liver cirrhosis
c) Atherosclerosis
d) Pancreatitis
Answer: Atherosclerosis
Explanation:
The LPA gene codes for apo-lipoprotein (a), which, when linked with low-density lipoprotein particles, forms lipoprotein (a) [Lp (a)] – a well-studied molecule associated with coronary artery disease (CAD).
Q-198. 40 mm gap between two fibers of tropo-collagen which help in maintaining bone structure; is filled by
a) Fe++
b) Hydroxyapatite
c) Carbohydrate
d) Mg++
Answer: Hydroxyapatite
Explanation:
Collagen is composed largely of the amino acids glycine, proline, and hydroxy-proline, which together account for more than 50% of the amino acid composition.
Tropo-collagen is the subunit of collagen fibrils formed of three polypeptides.
Each of the three chains forms a left-handed helical poly-proline II type helix with three residues per turn. There is a 40 nm gap, also called the “hole zone”, between the ends of each of these units.
These “hole zones” are critical in mineralization, as they appear to be the site of mineral nucleation for hydroxy-apatite crystals. The crystals appear to grow and proliferate from this area.
Q-199. Which of the following estimates blood creatinine level most accurately?
a) Jaffe method
b) Jaffe’s Kinetic method
c) Technicon method
d) Enzyme method
Answer: Enzyme method
Explanation:
Though high performance liquid chromatography and gas chromatography with mass spectroscopy have been proposed to be gold standards for creatinine estimation but they are not readily available in most of the clinical chemistry laboratories due to economic and technical constraints.
Though enzymatic methods are now routinely used as most accurate method but they are not acceptable due to cost constraints.
Most of the present day analyzers use Jaffe’s kinetic method without deproteinization.
Q-200. Cytosolic Cytochrome C mediates
a) Apoptosis
b) Electron transport
c) Kreb’s cycle
d) Glycolysis
Answer: Apoptosis
Explanation:
Cytochrome c is primarily known for its function in the mitochondria as a key participant in the life-supporting function of ATP synthesis.
However, when a cell receives an apoptotic stimulus, cytochrome c is released into the cytosol and triggers programmed cell death through apoptosis.