What organelle is the site of translation? (A) Vacuole, (B) nucleus, (C) ribosome, (D) mitochondria, (E) cell membrane.
The key terms in this question are “organelle” and “translation.” Organelles are specialized structures within cells that have specific functions. And the solution options list five organelles. We need to select the organelle that is the site of translation, which is a step used in the synthesis of proteins.
So let’s review where the steps of protein synthesis occur in a cell. Here we have a diagram of a cell that includes the organelles listed in the solution options: a vacuole, the nucleus, a ribosome, mitochondria, and the cell membrane. Now, let’s add information to the diagram to highlight where the steps of protein synthesis, including translation, occur in a cell.
Protein synthesis begins in the nucleus, which stores DNA. A section of DNA that contains the genetic code required for the synthesis of a protein is called a gene. The first step of protein synthesis, called transcription, occurs inside the nucleus. The process of protein synthesis produces messenger or mRNA that transports the genetic code required to build a protein to the second step of protein synthesis.
Step two of protein synthesis is the keyword from our question: translation. Translation requires the movement of the mRNA produced in transcription from the nucleus to the ribosome, which is solution option (C). The ribosome moves along the length of the mRNA molecule as it helps assemble a growing chain of amino acids, forming a polypeptide that will go on to form the protein coded by the gene in the nucleus. So now we can select the correct answer to the question. The organelle that is the site of translation is the ribosome.
But let’s take a quick look at the other solution options for a bit of organelle function review. Vacuoles are involved in storage and waste processing but not protein synthesis, while the nucleus is involved in protein synthesis. It’s involved in the first step, transcription, not step two, translation. Mitochondria from option (D) produce ATP, the energy currency of the cell. While ATP is necessary for protein synthesis, including translation, mitochondria are not the site of translation. Finally, option (E) the cell membrane, the cell membrane helps a cell maintain homeostasis by controlling which substances move in and out of the cell. But it’s not the site of translation.
Therefore, the answer to the question “What organelle is the site of translation?” is the ribosome.