Genetics is the scientific study of genes and heredity—of how certain qualities or traits are passed from parents to offspring as a result of changes in DNA sequence. A gene is a segment of DNA that contains instructions for building one or more molecules that help the body work.
Three of the major characteristics used to classify organisms are cell structure, mode of nutrition and cellularity. These characteristics help scientists determine how organisms are similar to each other as well as how they are different from each other.
