Difference between Non-Coding and Junk DNA

Hi there, here's my understanding.

The two are not the same.

Junk DNA is DNA that is found outside of start and stop sequences.
Non-coding DNA is the DNA that's found within a gene that gets spliced out during transcription of mRNA.

Selective mRNA splicing plays a role in regulating gene expression, and depending on the organisms needs, what gets spliced could vary, making some non-coding DNA actually important.

Hope this clarifies things

Do u mean all Intros are non-coding DNA ?
How is a gene designated as start and stop? ( I knw about start and stop codon)
its said that we have 98% Junk DNA in human Genome, does it include Non-Coding as well

First, both coding and noncoding regions of DNA are transcribed into mRNA, hence it's part of the gene. Therefore, the noncoding regions include all the 5′UTR, 3′UTR.


Anything that's intergenic is technically "junk" DNA. However, biologists don't like using this phrase, and here's why: just because we don't know its purpose, doesn't mean we can denounce it as being useless or junk. In fact, it has been suggested that junk DNA serves as a gene reservoir from which potentially advantageous new genes might emerge. So it might not really be "junk" after all.

Updated my post