Dna remains in the nucleus. mrna can travel in and out of the nucleus. explain how the function of dna and mrna differs.

DNA is basically the hard copy. It is double stranded and found in every cell. It contains a library of EVERY single protein that the body makes. Cells supress bits of the DNA because every protein does not apply to every cell. 

mRNA is the portable version that is taaken away from the hard copy to make the actual protein. It is single stranded and codes for 1 protein (although in bacteria one mRNA can code for many proteins). It is the actual bit that gets TRANSCRIBED in the nucleas (copied) and TRANSLATED (written) into proteins in the cytoplasm on ribosomes (which are incidently another form of RNA...rRNA). 

DNA functions include getting copied to every daughter cell too

I'm soooo sorry but i can't answer but you can ask another professor