Which of the following statements concerning ribosomes are true?

• A. Several ribosomes are often attached to and translating the same mRNA.
• B. Ribosomes join amino acids to form a polypeptide.
• C. Ribosomes have a binding site for mRNA and three binding site for tRNA molecules.
• D. No protein synthesis within a cell would occur without ribosomes.
• E. All of the above statements are true.

Answer: (E)

Verified step by step guidance

1. Understand the role of ribosomes in protein synthesis. Ribosomes are the cellular structures responsible for translating mRNA into polypeptides, which are chains of amino acids.
2. Recognize that ribosomes can simultaneously translate the same mRNA molecule. This is known as polysome formation, where multiple ribosomes attach to a single mRNA strand, increasing the efficiency of protein synthesis.
3. Identify the structural features of ribosomes. Ribosomes have a binding site for mRNA and three binding sites for tRNA molecules, which are crucial for the translation process.
4. Acknowledge the necessity of ribosomes for protein synthesis. Without ribosomes, cells would be unable to synthesize proteins, which are essential for various cellular functions.
5. Conclude that all the given statements about ribosomes are true, as they accurately describe the functions and characteristics of ribosomes in the context of protein synthesis.