Final answer:
An organism's traits are determined by the combination of inherited genes that make up its genotype, which in turn dictates the phenotype, or observable traits. The genetic information is encoded in DNA, and genes specify protein structures.
Step-by-step explanation:
An organism's traits are determined by the specific combination of inherited genes. Traits are the various characteristics that an organism can exhibit, like hair color, height, and skin color. These traits are described as the organism's phenotype. The genotype, on the other hand, refers to the genetic makeup of an individual which is composed of DNA and represents the combination of alleles for each gene. Alleles are different forms of a gene that arise by mutation and are found at the same place on a chromosome.
The inheritable characteristics of organisms are coded by the sequences of nucleotides in the DNA which make up the genes. These sequences specify the order of amino acids in proteins, which carry out most cellular functions. This is why the study of genes goes hand in hand with the study of the proteins they encode.