In: Biology
Would you be more likely to find single nucleotide polymorphism in the protein-coding or in the noncoding dna of the human genome? Please explain, I do not understand the key.
Single neucleotide polymorphism is a variation in a single neucleotide in a genome.
For example lets say following is the genome sequence of a particular gene in most of the human DNA
AGGTTAACCGGT
TCCAATTGGCCT
Now the genome with SNP will be
AGGTTACCCGGT
TCCAATGGGCCT
So this SNP's are most frequent in non-coding strand of the genome than the coding strand. This is because SNP in a coding strand changes the aminoacid sequence and thus can produce defective proteins, it is a main reason for different diseases such as sickle cell anaemia, cystic fibrosis etc. Now due to natural selection most of the SNPs in coding strands are removed by DNA proofreading mechanism for better genetic adaptation.
But the SNPs present in non-coding strand do not cause major changes in protein function or its formation and thus these SNPs gets overlooked by natural selection and stays within the genome making it more frequent in a population.