I don't understand why there is non-coding DNA

isn't there only 24 possible combinations possible? what possibilities are non-coding?

there is heaps of combinations in dna. If you were refering to amino acids, there is 64 combinations but we can only make 20.
During transcription, a pre mRna is made from its template DNA, the pre mRNA contains the intron ( non coding region of the DNA) then goes under post transcriptional modifications to get the introns spliced off. People are still not sure as to why the introns exist but it is currently useful in forensics in determining the victim of the crime.

Non coding DNA actually doesnot have a defined and specific role in our body functions normally,but it is thought to be a remnant of our evolutionary trace.As name suggests it doesnot code for any proteins required for our body but helps to compare our origin with that of some other organism, for example, we say the DNA of rat and ours are the same for almost 98%.This is on the basis of non coding DNA sequences of both the species.

There are 64 potential codons, but it is not the number but rather if they are put to use. Non-coding refers to segments that do not become proteins. This includes important segments that become ribosomal or transfer RNA.

To use an analogy, a book chapter might finish halfway down the page. What good is the empty space? You could read words interspersed in gibberish. So long as you can figure out where to start and stop reading, the gibberish is not going to impact your comprehension.

"isn't there only 24 possible combinations possible?"

Sorry, I don't know where you are coming up with that.



Non-coding DNA is DNA that does not code for either a protein or a functional RNA product. Introns are non-coding DNA, and so are enhancers and silencers, for example.

I didn't know this existed. You must be in a specialized field in College. I did not know that there is non-coding DNA.