Which term is the site of protein synthesis and is primarily RNA-based?

Which term is the site of protein synthesis and is primarily RNA-based?

• A. Endoplasmic reticulum
• B. Cytoplasm
• C. Nucleus
• D. Ribosome

Answer: (D)

Ribosomes are the cellular machines that carry out protein synthesis by translating the genetic code on mRNA into a polypeptide. What makes them the best answer here is that their catalytic activity is RNA-based: the ribosomal RNA (rRNA) forms the peptidyl transferase center that actually forms the peptide bonds between amino acids. The ribosome is a ribonucleoprotein particle, built from rRNA and proteins, with rRNA doing the essential chemical work and proteins providing support and structure. mRNA is produced in the nucleus and travels to where ribosomes are in the cytoplasm or on the rough endoplasmic reticulum, where translation occurs. The endoplasmic reticulum is involved for certain secreted or membrane proteins when ribosomes are bound to its surface, but the actual site of protein synthesis is the ribosome itself. The nucleus houses the genetic material, and the cytoplasm is the environment where ribosomes operate, but the specialized site that performs the synthesis—and does so via RNA-based catalysis—is the ribosome.

Ribosomes are the cellular machines that carry out protein synthesis by translating the genetic code on mRNA into a polypeptide. What makes them the best answer here is that their catalytic activity is RNA-based: the ribosomal RNA (rRNA) forms the peptidyl transferase center that actually forms the peptide bonds between amino acids. The ribosome is a ribonucleoprotein particle, built from rRNA and proteins, with rRNA doing the essential chemical work and proteins providing support and structure.

mRNA is produced in the nucleus and travels to where ribosomes are in the cytoplasm or on the rough endoplasmic reticulum, where translation occurs. The endoplasmic reticulum is involved for certain secreted or membrane proteins when ribosomes are bound to its surface, but the actual site of protein synthesis is the ribosome itself. The nucleus houses the genetic material, and the cytoplasm is the environment where ribosomes operate, but the specialized site that performs the synthesis—and does so via RNA-based catalysis—is the ribosome.