Dictionary

German measles See rubella.

germ cell tumor A tumor that arises from a germ cell. A germ cell tumor may arise within the gonads (in the ovary or testis). Most testicular tumors, in fact, are germ cell tumors. Germ cell tumors also may arise in extragonadal sites, reflecting the fact that germ cells travel to diverse areas of the…

germ cell Either the egg or the sperm cell; a reproductive cell. Each mature germ cell is haploid, meaning that it has a single set of 23 chromosomes containing half the usual amount of DNA and half the usual number of genes. Except for the egg and the sperm, most cells in the human body…

GERD Gastroesophageal reflux disease.

genu The Latin word for knee, as in genu recurvatum (hyperextension of the knee), genu valgum (knock knee), and genu varum (bowleg). See knee.

genotype The genetic constitution (genome) of a cell, an individual, or an organism. The genotype is distinct from the expressed features, or phenotype, of the cell, individual, or organism. The genotype of a person is that person’s genetic makeup. It can pertain to all genes or to a specific gene.

genomics The scientific study of the genome, the complete genetic information contained within an organism. See also genome.

genomic library A collection of clones that is made from a set of randomly generated overlapping DNA fragments and that represents the entire genome of an organism. Also known as clone bank.

genome, nuclear See genome, chromosomal.

genome, mitochondrial The sum of the genetic information contained in the chromosome of the mitochondrion, a structure located in the cytoplasm outside the nucleus of the cell. The mitochondrial genome is composed of mitochondrial DNA (mDNA), a double-stranded circular molecule that contains a limited number of genes. During fertilization, mDNA is transmitted only by the…

genome, human All the genetic information in a person. The human genome is made up of the DNA in chromosomes as well as the DNA in mitochondria.

genome, chromosomal All the genetic information in the chromosomes of an organism. For humans, the chromosomal genome is all the DNA contained in the normal complement of 46 chromosomes in virtually every cell in the body. Together with the mitochondrial genome, the chromosomal genome constitutes the genome of the human being. Also known as nuclear…