A Level Biology Practice Exam

What is the primary function of ribosomes?

1. Energy production

2. Protein synthesis

3. Photosynthesis

4. Cell division

The correct answer is: Protein synthesis

Ribosomes are essential cellular structures responsible primarily for the synthesis of proteins. They achieve this by translating messenger RNA (mRNA) into polypeptide chains, which will eventually fold into functional proteins. This process, known as translation, occurs in two main stages: initiation, where the ribosome assembles around the mRNA, and elongation, where amino acids are brought to the ribosome by transfer RNA (tRNA) in the correct sequence dictated by the mRNA. Protein synthesis is critical for numerous cellular functions, as proteins play vital roles in almost all biological processes, including enzymatic reactions, structural roles, transport, and communication within and between cells. The versatility of ribosomes, which can be found free-floating in the cytoplasm or attached to the endoplasmic reticulum, highlights their importance in both prokaryotic and eukaryotic cells for producing the diverse array of proteins necessary for life.