significance of dna sequences non coding regions of dna

• DNA sequences in the non-coding region of DNA control gene expression. They control when and where genes are expressed, the location where splicing to remove introns (non-coding regions of mRNA) and location where ribosome bind to the mRNA
• • Mutation in non-coding DNA region →  affects the production of RNA responsible for splicing (removal of introns) prior to translation →RNA loses function → some introns will not be spliced away in mRNA before translation→ introns now remain → intron signals for a stop codon during the translation →  amino acid sequence changed → polypeptide chain changes → Structure and/ or function of protein changed 
• • In other case  → intron not spliced can lead to some exons (coding regions) to be skipped → amino acid may not be specified as a result 
• • Mutations in non coding DNA region of gametes can result in birth defects 
• DNA sequences in coding regions of DNA specify for protein that is produced via protein synthesis. 
• • DNA sequence in the coding DNA region is responsible for mRNA sequencing during transcription. 
• • Then, the mRNA codons each specify for an amino acid → results in amino acid sequence of polypeptide chain during translation 
• Mutation in coding region DNA → affects mRNA sequence, amino acid sequence and structure & function of the protein
• Resulting protein may lose some OR all of its efficiency in performing its function due to changes in its structure. This changes physical, physiological and behavioural traits of an organism can be affected (as proteins are responsible for them).
• X-ray  causes mutations in coding DNA → enzyme’s (protein) structure altered → cannot catalyse  reactions required to produce arginine amino acid.