Video Transcript
State the eukaryotic organelle
being described: This organelle contains RNA and is the site of protein
synthesis.
This question asks us to determine
the name of a eukaryotic organelle, given its description. A eukaryotic cell contains many
specialized, membrane-bound organelles that are essential to carrying out its
functions. Some of these organelles, as well
as other cellular components, are shown in this simplified diagram of an animal
cell. We are given two clues to help us
figure out the correct organelle: it contains RNA and is the site of protein
synthesis.
The organelle responsible for the
synthesis of proteins in all cells, prokaryotic or eukaryotic, is the ribosome. Ribosomes are tiny structures that
are found free in the cytoplasm and attached to the rough endoplasmic reticulum. Their classification as organelles
is a bit controversial because unlike other eukaryotic organelles, they are
non-membrane bound, meaning they are not surrounded by a phospholipid bilayer.
Ribosomes consist of two ribosomal
subunits, one large and one small. These subunits are made of
ribosomal RNA, or rRNA, as well as proteins. To synthesize proteins, ribosomes
translate messenger RNA, or mRNA, containing the genetic code from nuclear DNA into
a strand of amino acids, also called a polypeptide chain. This polypeptide will eventually be
folded into a functional protein by the rough endoplasmic reticulum and packaged for
transport to its correct location by the Golgi apparatus.
We can see that ribosomes match the
two clues given in our description. So the organelle that contains RNA
and is the site of protein synthesis is the ribosome.
