Considering that we are all made up of the same four nucleot

Considering that we are all made up of the same four nucleotides in our DNA, the same four nucleotides in our RNA, and the same 20 amino acids in our proteins, why are we so different from each other?

Solution

Though we are all made of the same nucleotides and genome, we are different because of differences in gene expression pattern and differences in environmental exposure Differences in gene expression and post-transcriptional mRNA processing lead to greater difference in the proteome than the genome between the two cells.

The total set of proteins expressed by a genome or cell or tissue or organism under defined conditions is known as proteome. The genome present in all cells is almost same, but all genes are not expressed in all the cells/organisms. If you isolate a copy of the gene that codes for a protein found in the stomach, yes, you could find this gene to be located in cheek cells also, because the genome is same. But this gene is not expressed in cheek cells, means no mRNA and protein synthesis occurs in cheek cells. Actually, this is how the functions of each tissue is different from one another based on the cell type it is made of.

the same way, individuals may carry different alleles that code for different proteins, but the basic composition is always the same nucleotides and amino acids. Also, the expression of these alleles remain different in each individual, which contributes to physical differences.