Which of the following are essential amino acids? 1. Leucine 2. Tryptophan 3. Methionine 4. Cystine 5. Histid… - ESIC Nursing Officer-7July 2024

ESIC Nursing Officer-7July 2024

Applied Nutrition & Dietetics

Easy

Appeared in: ESIC Nursing Officer-7July 2024

Explanation

Essential amino acids are those that the body cannot produce and must be supplied through diet.
The nine essential amino acids are Histidine, Isoleucine, Leucine, Lysine, Methionine, Phenylalanine, Threonine, Tryptophan, and Valine.
Leucine (1), Tryptophan (2), Methionine (3), and Histidine (5) are all on the list of essential amino acids.
Cystine (4) is considered a non-essential or conditionally essential amino acid because the body can synthesize it from Methionine, which is an essential amino acid.

Option A: This option is incomplete as it omits Histidine.
Option B: This option incorrectly includes Cystine (4), which is a non-essential amino acid. It also omits the essential amino acids Leucine (1) and Tryptophan (2).
Option D: This option incorrectly includes Cystine (4), which is a non-essential amino acid.

Visual 1: Chart - A clear chart categorizing all 20 amino acids into three groups: Essential, Non-essential, and Conditionally Essential. This helps in memorizing the classification.
Visual 2: Infographic - An infographic showing dietary sources of complete proteins (containing all essential amino acids) versus incomplete proteins, with examples of how to combine foods like grains and legumes to form a complete protein.

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.
Nurses must understand the importance of essential amino acids for patient recovery, wound healing, and overall health.
Dietary counseling for patients, especially vegetarians, vegans, or those with malnutrition, should include information on combining different plant-based foods (e.g., rice and beans, bread and peanut butter) to ensure intake of all essential amino acids.
What if? - If a patient has a liver disease, their ability to synthesize non-essential amino acids might be impaired. In this case, some non-essential amino acids could become 'conditionally essential', requiring dietary supplementation.

How to Approach the Question

First, understand the question. It asks to identify the 'essential' amino acids from the given list.
Recall the definition of an essential amino acid: one that the body cannot synthesize and must be obtained from the diet.
Mentally (or by writing down) list the nine essential amino acids: PVT TIM HALL (Phenylalanine, Valine, Threonine, Tryptophan, Isoleucine, Methionine, Histidine, Arginine, Leucine, Lysine - note Arginine is semi-essential).
Evaluate each amino acid in the question's list: Leucine (Essential), Tryptophan (Essential), Methionine (Essential), Cystine (Non-essential), Histidine (Essential).
Eliminate any option that includes Cystine (item 4). This rules out options B and D.
Compare the remaining options. Option A (1, 2, 3) is missing Histidine (5). Option C (1, 2, 3, 5) includes all the essential amino acids from the list.

Concept Tested & Keywords

Concept Tested: Classification of essential and non-essential amino acids
Stem keywords: essential amino acids, Leucine, Tryptophan, Methionine, Cystine, Histidine
Lead-in keywords: Which of the following are

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