Which of the following statements is true of essential amino acids?
a. These amino acids do not contain a side chain attached to the backbone.
b. Alanine and cysteine are examples of essential amino acids.
c. These amino acids cannot be synthesized by the body:
d. Their recycling is different from that of nonessential amino acids. These amino acids are produced in excess within the body:
The correct answer and explanation is:
The correct answer is: These amino acids cannot be synthesized by the body.
Explanation:
Essential amino acids are amino acids that the body cannot synthesize on its own and must be obtained through the diet. Unlike nonessential amino acids, which the body can produce by converting other compounds or from existing amino acids, essential amino acids must be consumed in foods. The human body needs 9 essential amino acids for proper functioning. These are histidine, isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan, and valine. Without a sufficient intake of these essential amino acids, the body cannot properly produce proteins, enzymes, or other molecules required for bodily functions.
Each amino acid has a specific role in protein synthesis, and their presence is vital for the production of muscle tissue, enzymes, hormones, and other key proteins. If an individual does not consume enough essential amino acids, protein synthesis will be impaired, which can lead to muscle breakdown, weakened immune response, and other health problems.
On the other hand, nonessential amino acids are those that the body can produce itself using the intermediates from essential amino acids. For instance, the body can synthesize alanine and cysteine, so these are nonessential amino acids.
The other statements in the options are incorrect. Essential amino acids do contain a side chain that differentiates them from other amino acids. Alanine and cysteine are not essential amino acids, as both can be synthesized by the body. Additionally, the recycling process for amino acids, whether essential or nonessential, generally involves breaking down old proteins into amino acids, which are then reused or excreted. However, essential amino acids themselves cannot be produced by the body, meaning their recycling is not a factor in their synthesis.
In summary, essential amino acids must be acquired from external sources because the body is unable to produce them, making it crucial to consume them through a balanced diet to maintain good health.