"A gene pool consists of all genes, including all the different alleles that are present in a population. Number of times an allele occurs in a gene pool compared with the number of times other alleles occur. In genetic terms, evolution is any change in the relative frequency of alleles in a population."
DNA carries all of the information for your physical characteristics, which are essentially determined by proteins. So, DNA contains the instructions for making a protein. In DNA, each protein is encoded by a gene (a specific sequence of DNA nucleotides that specify how a single protein is to be made).
I can't draw very well. but, essentially the shape of DNA is a double helix and A pairs with T and T pairs with A. C pairs with G and G pairs with C. No matter what in DNA. What one side has the other side has. The other will always have the match to it on the other side
A= adenine
T=thymine
C=Cytosine
G=guanine