How many different essential amino acids are used in the synthesis of body proteins?

• A. 9
• B. 20
• C. 8
• D. 11

Answer: (A)

Verified step by step guidance

1. Understand that amino acids are the building blocks of proteins, and essential amino acids are those that cannot be synthesized by the body and must be obtained from the diet.
2. Recognize that there are 20 standard amino acids used in protein synthesis, but not all of them are essential.
3. Identify the essential amino acids, which are those that the human body cannot produce on its own. These must be consumed through food.
4. Recall that there are 9 essential amino acids: histidine, isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan, and valine.
5. Conclude that the number of different essential amino acids used in the synthesis of body proteins is 9.