What are ribosomes? What do they do?
Ribosomes are structures in cells built from rRNA. There are genes (regions of DNA) which are transcribed to produce rRNA molecules. The ribosome is made of a smaller and a larger rRNA subunits. The size of these subunits is different in prokayrotic and eukaryotic cells.
Eukaryotic ribosome = 80S (40S and 60S)
Prokaryotic = 70S (50S and 30S)
I know the numbers look strange, that's because Svedberg units are not additive.
The job of the ribosome is to read mRNA in the process of of translation. This is how cells build proteins that will determine traits of an organism.
This video discusses the process of transcription (how RNA is made) and also the process of translation (how ribosomes read RNA messages to build protein).
Hope this helps!