What is the term for an organism's genetic makeup?

The term that refers to an organism's genetic makeup is genotype. The genotype encompasses all the specific alleles that an organism possesses, which determine traits inherited from its parents. It is crucial for understanding heredity, as it provides the underlying genetic framework that influences both physical characteristics and physiological functions.

The other terms relate to different aspects of genetics. Phenotype, for instance, describes the observable characteristics of an organism, which result from the interaction between its genotype and the environment. Alleles are variations of a gene that can exist at a specific locus on a chromosome, whereas chromosomes are structures within cells that contain DNA and house the genes themselves. These components are all integral to the study of genetics, but genotype specifically focuses on the complete set of genes and their variants within an individual organism.