Phenotype
The physical characteristics of an organism or the presence of a disease that mayor may not be genetic. 2. Observable traits or characteristics of an organism produced by the individual's genes interacting with the environment(ie. Hair color, height, weight, presence or absence of disease). 3. The observable characteristics of an organism that are genetically controlled. 4. The physical or functional characteristics of an organism, produced by the interaction of genotype and environment during growth and development. 5. The observable properties of an organism, produced by the genotype in conjunction with the environment.

Pheromone
A chemical substance produced by some organisms and emitted into the environment to communicate with others of the same species. Pheromones play an important role in the social behavior of certain animals, especially insects and some mammals. They are used to mark out territories, to attract mates, to lay trails, and to promote social cohesion and coordination in colonies.

Examples are the sex attractants secreted by moths to attract mates and the queen substance produced by queen honeybees, which controls the development and behavior of worker bees. Pheromones are usually volatile organic molecules which are effective at very low concentrations, as little as 1 part per million.

Philadelphia Chromosome
A structural abnormality of chromosome 22 typically occurring in a proportion of bone marrow cells in patients with CML (chronic myelogenous leukemia) whereby a reciprocal translocation occurs between chromosomes 9 and 22.

Phosphodiester bond
The covalent bond between the 5' phosphate group on one nucleotide and the 3' hydroxyl group on an adjacent nucleotide; the bond that forms the backbone of the DNA molecule.