What is the role of ribosomes in cells?

Ribosomes play a crucial role in the process of protein synthesis, which is fundamental to cellular function and the growth of organisms. They are the cellular machinery that translates messenger RNA (mRNA) into amino acid sequences, linking amino acids together to form proteins according to the genetic instructions carried by the mRNA. This process occurs in two main stages: transcription, where DNA is transcribed to mRNA in the nucleus, and translation, which takes place in the ribosome.

During translation, ribosomes read the sequence of the mRNA in sets of three nucleotides called codons, each of which corresponds to a specific amino acid. Transfer RNA (tRNA) molecules bring the appropriate amino acids to the ribosome, and the ribosomes facilitate the formation of peptide bonds between these amino acids, constructing a polypeptide chain that will either function as a protein or fold into a functional structure.

The other options presented do not involve ribosomes directly. Energy production primarily occurs in the mitochondria, lipid synthesis involves the smooth endoplasmic reticulum, and DNA replication takes place at specific sites within the nucleus through the action of DNA polymerase and other enzymes. Thus, the specific and essential function of ribosomes is indeed centered around protein synthesis.