Tagged: Tyrosine

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Nonessential in normal health but essential during conditions of enhanced growth or surgical recovery

Case details An 8-year-old child requires surgical intervention and substantial recovery time in the hospital. A nutritionist recommends a specific dietary plan. The plan includes a protein rich diet with the special supplementation of an amino acid that is typically considered a nonessential, but becomes an essential amino acid under conditions of enhanced growth or surgical recovery. Which of the following amino acids should be considered in this dietary plan? A. Alanine B. Arginine C. Glycine D. Serine E. Tyrosine The correct answer is Arginine. Arginine is a semi essential amino acid. It can be synthesized in the human body...

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A common intermediate of Urea and TCA cycle

Question of the day Which one of the following can be converted to an intermediate of either the citric acid cycle or urea cycle? A. Tyrosine B. Lysine C. Leucine D. Tryptophan E. Aspartate Answer- The correct answer is- E -Aspartate. 1) Role of Aspartate in urea cycle Aspartate participates in urea cycle for condensation with citrulline to form Argino succinic acid. The reaction is catalyzed by Argino succinic acid synthetase (Aspartate provides one out of the two nitrogens of urea, the other nitrogen is contributed by Glutamate). In the subsequent reaction, Argino succinic acid undergoes a lytic reaction to...

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Which amino acid is both glucogenic as well as ketogenic ?

A 54-year-old male who was diagnosed with HIV (human immuno deficiency virus) infection 2 years back, is currently in the terminal stage. He is now cachectic and having a difficult time obtaining any caloric intake yet he refuses to take a naso gastric or gastric feeding tube. Since his muscle and organs are metabolically active, which of the following amino acids will produce both glucose and ketone bodies as an energy source? A. Alanine B. Tyrosine C. Proline D. Glycine E. Leucine The correct answer is B- Tyrosine. Amino acids can be classified based on their metabolic fate- I) Purely...

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Answer- Case study- Epilepsy

Question of the day A 12-year-old boy develops convulsions. After running an electroencephalogram (EEG), a neurologist determines that the child has epilepsy. He is started on Benzodiazepine, which promotes the activity of GABA. GABA is derived from the amino acid glutamate via which of the following biochemical reactions? A. Deamination B. Decarboxylation C. Hydroxylation D. Iodination E. Methylation Answer- The correct answer is B- Decarboxylation, Glutamic acid undergoes decarboxylation to yield GABA. The reaction is catalyzed by Glutamic acid decarboxylase that requires vitamin B6-P as a coenzyme. GABA is an inhibitory neurotransmitter and is thus helpful in controlling convulsions. Deamination...

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Answer- Case study- Oral contraceptives induced vitamin deficiencies

Case Details Oral contraceptives are known to lower blood levels of folate and vitamin B6. Which of the following conversion processes might be directly affected? A. Ornithine to Citrulline B. Histidine to histamine C. Glutamate to Glutamine D. Propionyl co A to Methyl malonyl co A E. Phenyl alanine to Tyrosine Answer- B- The correct answer is conversion of Histidine to histamine. The reaction is catalyzed by decarboxylase that requires B6-P as a cofactor (Figure-1) that gets deficient in women upon long-term oral contraceptive usage. Folic acid is not required in this reaction. Figure-1- Decarboxylation of Histidine is carried out...

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Case- Oral contraceptive induced Vitamin deficiencies

Question of the day Oral contraceptives are known to lower blood levels of folate and vitamin B6. Figure- Oral contraceptives Which of the following conversion processes might be directly affected ? A. Ornithine to Citrulline B. Histidine to histamine C. Glutamate to Glutamine D. Propionyl co A to Methyl malonyl co A E. Phenyl alanine to Tyrosine For answer follow the link http://usmle.biochemistryformedics.com/answer-case-study-oral-contraceptives-induced-vitamin-deficiencies/ Please help Biochemistry for Medics by “CLICKING ON THE ADVERTISEMENTS” every time you visit us. Thank you!

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Answer- Case study- Amino acid supplements- A 27- year-old, semiprofessional tennis player seeks advice from a hospital-based nutritionist…

AMINO ACID METABOLISM A 27- year-old, semiprofessional tennis player seeks advice from a hospital-based nutritionist concerning his diet supplements. His coach had given him amino acid supplements consisting of phenyl alanine and tyrosine. The rationale was that these precursors to several neurotransmitters will “help his brain focus” on his game. In reality, the excess amino acids are used for energy, with a poor and eclectic diet. Phenyl alanine upon metabolism enters TCA cycle as which of the following? A. Oxaloacetate B. Fumarate C. Succinyl co A D. Citrate E. α- Keto glutarate Answer- The right answer is B- Fumarate. Phenyl...

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Case study- Amino acid supplements-A 27- year-old, semiprofessional tennis player seeks advice from a hospital-based nutritionist concerning his diet…

QUESTION OF THE DAY AMINO ACID METABOLISM A 27- year-old, semiprofessional tennis player seeks advice from a hospital-based nutritionist concerning his diet supplements. His coach had given him amino acid supplements consisting of phenyl alanine and tyrosine. The rationale was that these precursors to several neurotransmitters will “help his brain focus” on his game. Figure- Amino acid supplements In reality, the excess amino acids are used for energy, with a poor and eclectic diet. Phenyl alanine upon metabolism enters TCA cycle as which of the following? A. Oxaloacetate B. Fumarate C. Succinyl co A D. Citrate E. α- Keto glutarate...

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