What are three places where ribosomes occur in a cell?

Ribosomes can be found in

1) Cytoplasm

2) Mitochondria

3) On the surface of Endoplasmic Reticulum

Explanation:

In eukaryotes, ribosomes form within the nucleolus, a structure inside the cell's nucleus. As ribosomal proteins enter the nucleus, they join with four rRNA strands to form a whole ribosome. The subunits exit the nucleus through pores and start protein synthesis within the cytoplasm of the cell.

"1. it should be, it has been for about 20 years, and it's really not much different in the end than breeding animals to have particular traits. there are always concerns about genetically engineered animals/plants affecting the environment in unexpected negative ways, but i can't think of an example where the fears didn't turn out to be baseless.  

first, as you point out, it would be a great advance in pharmacology, to be able to tailor drugs and their doses to me. the pros involve better medical treatment. the cons involve privacy issues like insurance companies denying coverage to people with genetic risk factors. looking at dna markers wouldn't affect the frequency of genetic diseases, but it would allow detection of them earlier. and ok, actually i suppose that if people used this information to avoid having children with genetic diseases, some might decrease in frequency."