Nucleotide segment that codes for amino acids.

Expressed sequence tag (EST)

A DNA sequence complementary to a known piece of transcribed RNA.

Forward genetics

An approach to identify a particular gene starting with some knowledge about a mutant phenotype.

Functional genomics

The systematic and comprehensive analysis of gene products, including mRNAs and proteins.


The fundamental units of heredity carried by DNA.

Gene product

The mRNA resulting from transcription of a gene and the protein translated from the mRNA.

Gene targeting

The production of a mutation in a specific “target” gene using molecular biological techniques.


The study of the genetic composition of organisms.


An organism’s genetic makeup (i.e., its DNA sequence).


A region of the homeotic genes that is highly conserved among several species, including Drosophila, frogs, and mammals. The homeobox sequence encodes a DNA-binding motif of the encoded protein that is a transcription factor.

Homologous recombination

Crossing over between two identical or homologous strands of DNA.

Human Genome Project

A federally funded initiative to sequence and identify (HGP) all human genes. HGP also involves studying the genome of a number of organisms other than humans, including insects, fish, plants, and other mammals.

Inbred strain

A strain of mice that has been inbred by brother-sister matings for more than 20 generations, and consequently all the individuals of the strain are more than 98% genetically identical.


DNA sequence between exons that is transcribed but not translated

Knockout mutation

A mutation that leads to the loss of function of a particular gene. Also called a null mutation.

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