MDS PREP
Glutamate-pyruvate trans-aminase is predominantly present In:
1. Skeletal muscle
2. Cardiac muscle
3. Brain
4. Liver
Biochemistry
Answer: 4
Glutamate-pyruvate trans-aminase is predominantly present In Liver
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
Iodine is a characteristic component of
1. Cysteine
2. Tyrosine
3. Thyroxine
4. Thiamin
Biochemistry
Answer: 3
odine is a characteristic component of Thyroxine
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
An important rate limiting step of Kreb's cycle is catalysed by
1. pyruvate dehydrogenase
2. isocitrate dehydrogenase
3. succinate dehydrogenase
4. citrate synthetase
Biochemistry Answer: 2
Rate limiting step of Kreb's cycle is catalysed by isocitrate dehydrogenase
Which of the following amino acids is a
precursor for epinephrine?
1. Valine
2. Leucine
3. Tyrosine
4. Cysteine
Biochemistry
Answer: 3
Epinephrine, also known as adrenaline, is a hormone and neurotransmitter that
is synthesized in the body from the amino acid tyrosine. Tyrosine is a
non-essential amino acid, which means that it can be synthesized in the body
from phenylalanine, another essential amino acid. The synthesis of epinephrine
occurs in two main steps:
1. Hydroxylation of tyrosine: Tyrosine is converted into dihydroxyphenylalanine
(DOPA) by the enzyme tyrosine hydroxylase. This is the rate-limiting step in the
synthesis of epinephrine.
2. Decarboxylation and further hydroxylation: DOPA is then decarboxylated to
form dopamine, which is further hydroxylated to produce norepinephrine.
Norepinephrine is the immediate precursor of epinephrine.
3. Formation of epinephrine: Norepinephrine is methylated by the enzyme
phenylethanolamine N-methyltransferase (PNMT) and converted into epinephrine.
The other amino acids listed are not directly involved in the synthesis of
epinephrine:
1. Valine and Leucine are branched-chain amino acids that are primarily involved
in the metabolism of muscles and energy production.
2. Cysteine is a sulfur-containing amino acid that is important for the
synthesis of proteins with disulfide bridges and is a precursor for other
molecules like glutathione and taurine, but not directly involved in the
synthesis of epinephrine.
Aromatic amino acid is:
1. Tyrosine 2. Histidine
3. Arginine 4. Lysine
Biochemistry
Answer: 1
Tyrosine is Aromatic amino acid
Symptoms from a riboflavin deficiency can be:
1. Cracks in the corner of the mouth (angular stomatitis)
2. Inflammation of the tongue (glossitis)
3. Eye and skin changes
4. All of the above
Biochemistry
Answer: 4
The eye change include an increase in blood vessels and inflammation of the conjunctivae, cornea is invaded by capillaries, producing opaque areas and even ulceration. Dermatitis characterized by a greasy and scaly reddened lesion develops on the skin around the nasolabial folds and may extend to a butterfly shape on the cheeks. There many also be lesions at the corners (canthi) of the eyes and lobes of the mouth.