Question

Essential amino acids cannot be synthesized due to _______.

• A. lack of enzymes
• B. lack of oxygen
• C. lack of energy
• D. lack of vitamins

Hint:

Essential amino acids are "essential" to eat because our cells lack the DNA blueprints to make the specific enzymes needed to synthesize their carbon backbones.

Answer 1

The Correct Option is A

Step 1: Understanding the Question:
The question asks why the human body cannot synthesize essential amino acids internally, requiring them to be obtained from the diet.

Step 2: Key Concepts and Approach:
Amino acids are classified as essential (must be supplied by diet) or non-essential (can be synthesized by the body).
The synthesis of any complex biological molecule requires specific biochemical pathways catalyzed by a sequence of enzymes.

Step 3: Detailed Explanation:

• Biosynthetic Complexity: Non-essential amino acids have relatively simple synthesis pathways, often requiring only one or two enzymatic steps from common metabolic intermediates.
Essential amino acids have highly complex, multi-step synthesis pathways, especially for constructing aromatic rings or branched carbon skeletons.

• Evolutionary Loss of Genes: Over evolutionary time, animal species lost the genes that encode the enzymes required to catalyze these complex pathways.
Because animals lacked these specific metabolic enzymes, they became dependent on plants and microorganisms (which still possess these enzymes) for these nutrients.

• Resource Availability: Cells have adequate oxygen, energy (ATP), and vitamins, but simply lack the genetic instructions and enzymes to build these specific amino acid skeletons.

Step 4: Final Answer:
The inability to synthesize essential amino acids is due to a lack of the necessary enzymes.