A phenotype can be the result of many factors, including an individual's genotype, environment, and lifestyle, and the interactions among these factors. The observed manifestation of a genotype, a phenotype may be expressed physically, biochemically, or physiologically. If a scientist needs to detect the presence of a very small amount of a particular DNA sequence, PCR can be used to amplify the amount of that sequence until there are enough copies available to be detected. Promoters are required for binding of RNA polymerase to initiate transcription. Proteins are required for the structure, function, and regulation of the body's cells, tissues, and organs, and each protein has unique functions.
Examples are hormones, enzymes, and antibodies.
The area of genetics concerned with the inheritance of continuously-varying traits. Most practical improvement programs involve the application of quantitative genetics. The DNA formed by combining segments of DNA from different types of organisms. A chemical found in the nucleus and cytoplasm of cells. RNA plays an important role in protein synthesis and other chemical activities of the cell.