Identification of the Rate-Limiting Step in the Synthesis of Norepinephrine

question 25

Multiple Choice

Identification of the rate-limiting step in the synthesis of norepinephrine was achieved by measuring the

• A) activity of dopamine  -hydroxylase in the presence of varying levels of dopamine.
• B) amount of DOPA produced after inhibition of tyrosine hydroxylase.
• C) amount of each relevant enzyme in the cytoplasm.
• D) amount of norepinephrine produced when the preparation was bathed in various precursors.
• E) amount of norepinephrine produced when various enzymes were inhibited.

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Definitions:

Rate-Limiting Factor

A term describing the component of a process that determines the overall rate or speed of the process, often the slowest step in a series of steps.

Dopamine Synthesis

The biochemical process by which the brain produces the neurotransmitter dopamine, a crucial substance involved in movement, motivation, and the experience of pleasure.

L-dopa

A precursor to dopamine used in the treatment of Parkinson's disease to increase dopamine levels in the brain.

Inhibitory Neurotransmitter

Chemical substances released by neurons in the brain to reduce the activity of other neurons, playing a key role in the modulation of neural circuits.