MDS PREP
.Glucose can be synthesised from all of the following except
1. amino acids 2.Glycerol
3. Acetoacetate 4.Lactic acid
Biochemistry
Answer: 1
Glucose can be synthesised from Glyerol, Acetoacetate, Lactic acid
Hyperuricemia in Lesch-Nyhan syndrome is due to a defect in which of the following pathways?
1) Purine biosynthesis
2) Pyrimidine biosynthesis
3) Purine salvage
4) Pyrimidine salvage
Biochemistry Answer: 3
Uric acid is a purine derivative, increased by purine salvage reactions that convert purines, purine ribonucleosides, and purine deoxyribonucleoside to mononucleotides (incorrect answer 4).
Such salvage reactions require much less energy than de novo synthesis (incorrect answers 1, 2). The liver is the major site of purine nucleotide biosynthesis and provides excess purines for other tissues that cannot synthesize purines.
A defect in hypoxanthine-guanine phosphoribosyl transferase, one of the enzymes of purine salvage, is responsible for purine overproduction and subsequent hyperuricemia observed in Lesch-Nyhan syndrome.
Approximately 3 hours following a well-balanced meal, blood levels of which of the following are elevated?
1) Fatty acids
2) Glucagon
3) Glycerol
4) Chylomicrons
Biochemistry Answer: 4
Following digestion, the products of digestion enter the bloodstream.
These include glucose, amino acids, triacylglycerides packaged into chylomicrons from the intestine, and very low density lipoproteins from the liver.
The hormone of anabolism, insulin, is also elevated because of the signaling of the glucose and amino acids in the blood, which allows release of insulin from the β-cells of the pancreas. Insulin aids the movement of glucose and amino acids into cells. In contrast, all the hormones and energy sources associated with catabolism are decreased in the blood during this time. Long-chain fatty acids and glycerol released by lipolysis from adipocytes are not elevated. Glucagon and epinephrine are not released. The only time glucose levels rise significantly above approximately 80 mM is following a well-balanced meal when glucose is obtained from the diet. The concentration of glucose reaches a peak 30 to 45 minutes after a meal and returns to normal within 2 hours after eating. This response of blood glucose after eating (mimicked by giving 50 g of oral glucose) is the basis for the glucose tolerance test. In the event of insulin deficiency (diabetes mellitus), the peak glucose concentration is abnormally high and its return to normal is delayed.
A component of the coenzyme required in a transamination process is
1. Thiamine
2 Folic acid
3 Pyridoxine
4 Riboflavin
Biochemistry
Answer: 3
A component of the coenzyme required in a transamination process is Pyridoxine
Gout is a disease of purine overproduction. In this disease, joints develop crystals of
1. urea.
2. sodium urate.
3. guanine.
4. hypoxanthine.
Biochemistry
Answer: 2
Gout is a form of arthritis caused by the accumulation of uric acid crystals,
specifically sodium urate crystals, in the joints. The body produces uric acid
as a waste product during the metabolism of purines, which are substances found
in certain foods and also synthesized by the body. High levels of uric acid can
lead to the formation of these crystals, which cause inflammation and pain in
the affected joints. Urea (Answer 1) is a waste product formed from the
metabolism of proteins and amino acids, while guanine (Answer 3) and
hypoxanthine (Answer 4) are purine bases involved in nucleotide metabolism, but
they do not directly form the crystals seen in gout.
Anemia is frequently associated with a deficiency of
1. vitamins A and D.
2. vitamins C and D.
3. vitamins E and K.
4. vitamin B12 and folic acid.
Biochemistry
Answer: 4
Anemia is a condition characterized by a decrease in the number of red blood
cells or a reduction in their oxygen-carrying capacity. Vitamin B12 and folic
acid are essential for the production of red blood cells. Deficiencies in these
vitamins can lead to megaloblastic anemia, where the bone marrow produces
abnormally large and immature red blood cells.
If a biochemical test gives the same reading for a sample on repeated testing, it is inferred that the measurement is:
1. Precise.
2. Accurate.
3. Specific.
4. Sensitive.
repeatablity of test is precision and getting results within reference range is accuracy
An alpha helix of a protein is most likely to be disrupted if a missense mutation introduces the following armino acid within the alpha helical structure:
1. Alanine.
2. Aspartic acid.
3. Tyrosine.
4. Glycine.
Glycine and proline introduce a bend in structure of protein, hence alpha helix disrupted