Question

Conversion of L-Tyrosine to Epinephrine includes: A. L-Tyrosine $\rightarrow$ DOPA B. Norepinephrine $\rightarrow$ Dopamine C. DOPA $\rightarrow$ Dopamine D. Epinephrine $\rightarrow$ Norepinephrine Choose the correct answer from the options given below:

• A. A and D only \
• B. D and C only \
• C. A and C only \
• D. B and D only

Hint:

Remember the linear acronym: T $\rightarrow$ DO $\rightarrow$ DA $\rightarrow$ N $\rightarrow$ E (Tyrosine $\rightarrow$ DOPA $\rightarrow$ Dopamine $\rightarrow$ Norepinephrine $\rightarrow$ Epinephrine).

Answer 1

The Correct Option is C

Step 1: Concept The catecholamine biosynthetic pathway takes place in the central nervous system and the adrenal medulla. It step-wise transforms the amino acid L-tyrosine into key neurotransmitters and hormones.

Step 2: Meaning Catecholamines include dopamine, norepinephrine, and epinephrine. The conversion proceeds forward in a linear enzymatic sequence.

Step 3: Analysis Let us review the step-by-step pathway: 1. L-Tyrosine is hydroxylated by tyrosine hydroxylase to form L-DOPA $\rightarrow$ Statement A is correct. 2. L-DOPA undergoes decarboxylation by DOPA decarboxylase to form Dopamine $\rightarrow$ Statement C is correct. 3. Dopamine is hydroxylated by dopamine $\beta$-hydroxylase to form Norepinephrine $\rightarrow$ Statement B is inverted/incorrect. 4. Norepinephrine is methylated by phenylethanolamine N-methyltransferase to yield Epinephrine $\rightarrow$ Statement D is inverted/incorrect.

Step 4: Conclusion Statements A and C correctly represent actual forward transformations in the assembly pathway. Final Answer: (C)