What is the difference between coding and non-coding DNA?
Actually the answer to the last question is false. That is what we thought up until recently. First let me answer your question and then let me tell you why. Coding DNA is the particular part of the DNA that actually codes for a protein which is something useful. Non-coding DNA is the region of DNA that does not code directly for a protein. The reason why the other answer is false is because scientists used to think most of the DNA was non-coding because it did not code for a protein. What we know now is that RNA will transcribe for a sequence that at first is considered non-coding, but there are enzymes that will cut off parts of the DNA known as splicing and will recombine into an actual coding DNA that codes for a Protein.
What is the difference between introns and non-coding sequences of DNA?
non-coding just means that these parts of the DNA dont contain information for protein expression but actually some introns are coding because they are the residuals of retro-viruses and if you express these introns alone you will get a viral protein. also there is alternative splicing where an intron is sometimes not spliced whch results in a different protein.
What is the difference between exons and introns and coding vs. noncoding DNA?
exons - DNA sequence that codes for either an RNA or a protein. introns - bits of 'noncoding' sequence that are within exons. Introns are transcribed, but then spiced out before the final mRNA is released. coding: any DNA sequence that is transcribed into a protein or functional RNA. non-coding: stretches of DNA that appear to have no function. this does not mean it's junk sequence, it just means that we don't know of the function.