The instructions for making proteins are coded in the (cytoplasm / <u>DNA</u> / endoplasmic reticulum / nucleus) of a cell. In a eukaryotic cell, these instructions are located in the (cytoplasm / DNA / endoplasmic reticulum / <u>nucleus</u>).
Explanation:
The genetic code is contained in DNA, or deoxyribonucleic acid. This is usually the same among most organisms, save some RNA viruses. But in eukaryotes, the DNA is in the nucleus, whereas in prokaryotes the DNA is in the "nucleoid region", or a twisted up section near the middle of the cell.
