Which of the following is a non-essential amino acid?

Appeared in: Haryana CHO - 2022

Explanation

Alanine is classified as a non-essential amino acid.
This means the human body can synthesize it, primarily from the metabolic intermediate pyruvate, so it is not required to be obtained directly from the diet.
The body produces sufficient amounts of alanine to meet its biological needs for protein synthesis and other metabolic functions.

Option A: Leucine is an essential amino acid, meaning the body cannot produce it, and it must be supplied through diet.
Option B: Methionine is an essential, sulfur-containing amino acid that must be obtained from dietary sources.
Option D: Tryptophan is an essential amino acid that serves as a precursor for serotonin and melatonin; it must be consumed in the diet.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Classification of essential and non-essential amino acids as background academic context rather than a clinical decision trigger.
Understanding essential vs. non-essential amino acids is crucial for planning diets for patients with specific metabolic disorders (e.g., Phenylketonuria - PKU), malnutrition, or those on parenteral nutrition.
A balanced protein intake is necessary to ensure all essential amino acids are available for protein synthesis, wound healing, and immune function.
What if? If a patient has severe liver disease, the synthesis of some non-essential amino acids like tyrosine (from phenylalanine) can become impaired, making them 'conditionally essential' and requiring their supplementation in the diet.

How to Approach the Question

First, understand the question is asking to identify a 'non-essential' amino acid from the list.
Recall the definition: Non-essential amino acids can be synthesized by the body, while essential amino acids must be obtained from the diet.
Use a mnemonic to remember the essential amino acids, such as 'PVT TIM HALL'.
Check each option against the list of essential amino acids. Leucine, Methionine, and Tryptophan are part of the mnemonic.
The option not on the essential list (Alanine) is the non-essential amino acid and therefore the correct answer.

Concept Tested & Keywords

Qgo0xCInJAPrt__XFnEq3U

E6 Biochemistry U Satyanarayana— Part 1 (pp 26-420 of 840) p. 37-39

E6 Pharmacology Nursing Lilley 11e Part 3 p. 231-233

E6 Textbook of Biochemistry for medical StudentsDM Vasudevan Part 1 (pp 26-370 of 370) p. 292-294

Practise the full Haryana CHO - 2022

Attempt every question from this paper in a timed mock, then review the full solution for each one.