Algonquin College Health Program Assessment (AC-HPAT) Practice Exam

Which organelle is responsible for protein synthesis from RNA?

1. Mitochondria

2. Golgi apparatus

3. Ribosomes

4. Nucleolus

The correct answer is: Ribosomes

Ribosomes are the organelles responsible for protein synthesis from RNA. They function by translating the messenger RNA (mRNA) sequence into a polypeptide chain, which then folds into a functional protein. Ribosomes can be found either floating freely in the cytoplasm or attached to the endoplasmic reticulum, where they play a crucial role in the cellular machinery that translates genetic information into functional products. The process begins when mRNA, transcribed from DNA, moves to the ribosome. The ribosome reads the sequence of codons on the mRNA and facilitates the binding of transfer RNA (tRNA) molecules that carry specific amino acids. As tRNA molecules bring amino acids, the ribosome catalyzes the formation of peptide bonds between them, leading to the synthesis of proteins according to the genetic instructions encoded in the mRNA. In contrast, mitochondria are primarily involved in energy production through ATP synthesis, the Golgi apparatus is responsible for modifying, sorting, and packaging proteins for secretion or delivery to various parts of the cell, and the nucleolus plays a key role in ribosomal RNA (rRNA) synthesis and the assembly of ribosomal subunits, but it is not directly involved in protein synthesis itself.