What do ribosomes primarily synthesize?

• A. Fatty acids
• B. Proteins
• C. Nucleotides
• D. Carbohydrates

Answer: (B)

Ribosomes play a crucial role in the biological process of translation, which is the synthesis of proteins. They are complex molecular machines found within all living cells, and their primary function is to assemble amino acids into polypeptide chains based on the sequence of mRNA (messenger RNA). During this process, ribosomes read the mRNA codons and facilitate the binding of corresponding transfer RNA (tRNA) molecules that carry specific amino acids. This activity results in the formation of proteins, which are essential for numerous cellular functions, including enzymatic activity, structural roles, and signaling pathways.

The other choices involve biological molecules but are synthesized by different processes or cellular machinery. Fatty acids are synthesized by fatty acid synthases, nucleotides are synthesized in the nucleotides biosynthesis pathway, and carbohydrates are produced through processes like photosynthesis or cellular respiration, specifically by enzymes such as synthase. Thus, the primary function of ribosomes is indeed protein synthesis, making this the correct choice.