Final answer:
The genome is the total genetic composition of an organism, including all of its DNA. It is present in every cell and determines the organism's phenotype, with the study of genomes being known as genomics.
Step-by-step explanation:
The Genome: The Complete Genetic Composition of an Organism
The genome is the genetic composition of an organism, encompassing its entire complement of DNA. The genome includes both the genes, which are the functional units of heredity comprised of DNA sequences that code for specific peptides or RNA molecules, and non-coding DNA which plays a role in regulating gene expression. It can be found in every cell of an organism and is essential in determining the physical, behavioral, and biochemical characteristics expressed as a phenotype.
An organism's genome is a critical part of its biology, dictating the metabolic landscape, DNA-modification patterns such as methylation, and providing a template for the structure of proteins and RNA molecules. Genetics and genomics are fields of biology that study the structure, function, and evolution of genomes across species and within populations, highlighting the genetic diversity that serves as the raw material for evolution. Each human cell, for example, contains a complete genome distributed across 23 pairs of chromosomes, which includes autosomal chromosomes and sex chromosomes that determine the individual's sex.
Genomics is the study of entire genomes, addressing the complete set of genes, their nucleotide sequence and organization, and their interactions within and across species.