MDS PREP
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
Features of Vitamin C deficiency is due to defect of which enzyme
1. Lysyl hydroxylase
2. Lysyl oxidase
3. Procollagen peptidase
4. None of the above
Biochemistry
Answer: 1
Vitamin C deficiency is due to defect of Lysyl hydroxylase
The reaction used for estimating free amino, groups in proteins is:
1. Ninhydrin test
2. Deamination with HNO2
3. Biuret test
4. Formol titration
Biochemistry
Answer: 2
The reaction used for estimating free amino, groups in proteins is Deamination with HNO2
Epinephrine causes increased blood glucose level due to:
1. Increased glycogenolysis in liver and muscle
2. Activation of phosphorylase
3. Inhibition of glycogen synthesis in liver
4. All of the above
Biochemistry
Answer: 4
Epinephrine causes increased blood glucose level due to:
1. Increased glycogenolysis in liver and muscle
2. Activation of phosphorylase
3. Inhibition of glycogen synthesis in liver
Which of the following enzymes is active in adipocytes following a heavy meal?
1) Glycogen phosphorylase
2) Glycerol kinase
3) Hormone-sensitive triacylglyceride lipase
4) Phosphatidate phosphatase
Biochemistry Answer: 4
The enzyme phosphatidate phosphatase converts phosphatidic acid to diacylglycerol during synthesis of triacylglycerides.
The function of adipose tissue is the storage of fatty acids as triacylglycerols in times of plenty and the release of fatty acids during times of fasting or starvation.
Fatty acids taken in by adipocytes are stored by esterification to glycerol-3-phosphate. Glycerol-3-phosphate is derived almost entirely from the glycolytic intermediate dihydroxyacetone phosphate through the action of glycerol-3-phosphate dehydrogenase. Glycolytic enzymes are active in adipocytes during triglyceride synthesis, but those of glycogen degradation (low levels in adipocytes) and gluconeogenesis (ie, glucose-6-phosphatase) are not.
Glycerol kinase is not present to any great extent in adipocytes, so that glycerol freed during lipolysis is not used to reesterify the fatty acids being released.
The enzyme triacylglyceride lipase is turned on by phosphorylation by a cyclic AMP-dependent protein kinase following epinephrine stimulation.
After fasting for 24 hours, the major source of glucose for the whole body is
1. amino acids from muscle protein degradation.
2. ketone bodies from muscle triglycerides.
3. glycogen stored in the muscle.
4. creatine phosphate
Biochemistry Answer: 4
Creatine Phosphate is the major source of glucose for the whole body during starvation
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.
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.