Final answer:
The human body uses 20 standard amino acids to synthesize proteins, which are necessary for various physiological functions. These can be classified as essential, non-essential, and conditionally essential amino acids. Additionally, two rare amino acids are sometimes found in proteins, but they are not part of the standard 20 used in protein synthesis.
Step-by-step explanation:
In addressing the question of how many different amino acids are used in the synthesis of body proteins, the correct answer is c. 20. The human body uses a set of 20 standard amino acids to build proteins. These molecules are the building blocks of proteins and play a critical role in various biological processes. They can be categorized as essential, non-essential, or conditionally essential based on our body's capability to synthesize them.
Essential amino acids cannot be made by the body and therefore must be obtained through our diet. These are vitally important for numerous physiological functions, including the growth and repair of tissues. In contrast, non-essential amino acids can be produced by the human body, and conditionally essential amino acids are usually synthesized by the body but may need to be supplemented through diet under certain conditions such as illness or stress.
Although humans predominantly use 20 amino acids to construct proteins, there are two additional amino acids, Selenocysteine and pyrrolysine, found in limited quantities in some proteins. Nonetheless, for the vast majority of protein synthesis, especially considering the standard genetic code, the 20 standard amino acids are used.
Moreover, each amino acid corresponds to specific codons in the genetic code, with there being 64 possible codons to cover all 20 amino acids. The redundancy in this genetic system shows the sophistication of biological encoding and translation processes. In terms of RNA, it takes a sequence of three RNA 'letters', or nucleotides, to code for a single amino acid, forming what is known as a codon.
In summary, to answer your question, there are 20 common amino acids that are utilized in the synthesis of body proteins, making option c the correct choice.