"describe how dna serves as genetic information"

DNA encodes information in the form of the sequence of the 4 nucleotide bases; Adenine, Thymine, Guanine, and Cytosine. The sequence of these bases is read in groups of 3, after the DNA molecule has been transcribed into a RNA molecule. A group of 3 bases is called a codon. Each codon codes for a specific amino acid. The order of these amino acids will determine the final shape of the protein to be constructed. DNA is an extremely long molecule, with billions of bases, all of which are arranged in a specific order in specific regions that ultimately code for the genes that exist in the traits in the offspring. Some of these genes are expressed in the organism, others are simply carried by the organism and not expressed. DNA has regions that can be switched on and off under certain conditions, and can code for different things. DNA is the only molecule that can have seemingly infinite permutations to code for billions of different proteins. Cells are essentially machinery that execute the functions as directed by the DNA molecule. The only medium of genetic information transfer from a parent organism to the offspring is through the DNA molecule. The sequence of the bases in that DNA molecule IS the genetic information itself. To control the DNA sequence then, would be tantamount to custom designing an organism.

you know they are heterozygous for a trait because they have it as jj or jj.

you're crazy : )