lethal gene


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Related to lethal gene: epistasis

gene

 [jēn]
one of the biologic units of heredity, self-reproducing, and located at a definite position (locus) on a particular chromosome. Genes make up segments of the complex deoxyribonucleic acid (DNA) molecule that controls cellular reproduction and function. There are thousands of genes in the chromosomes of each cell nucleus; they play an important role in heredity because they control the individual physical, biochemical, and physiologic traits inherited by offspring from their parents. Through the genetic code of DNA they also control the day-to-day functions and reproduction of all cells in the body. For example, the genes control the synthesis of structural proteins and also the enzymes that regulate various chemical reactions that take place in a cell.

The gene is capable of replication. When a cell multiplies by mitosis each daughter cell carries a set of genes that is an exact replica of that of the parent cell. This characteristic of replication explains how genes can carry hereditary traits through successive generations without change.
allelic gene allele.
complementary g's two independent pairs of nonallelic genes, neither of which will produce its effect in the absence of the other.
DCC gene (deleted in colorectal carcinoma) a gene normally expressed in the mucosa of the colon but reduced or absent in a small proportion of patients with colorectal cancer.
dominant gene one that produces an effect (the phenotype) in the organism regardless of the state of the corresponding allele. An example of a trait determined by a dominant gene is brown eye color. See also heredity.
histocompatibility gene one that determines the specificity of tissue antigenicity (hla antigens) and thus the compatibility of donor and recipient in tissue transplantation and blood transfusion.
holandric g's genes located on the Y chromosome and appearing only in male offspring.
immune response (Ir) g's genes of the major histocompatibility complex that govern the immune response to individual immunogens.
immune suppressor (Is) g's genes that govern the formation of suppressor T lymphocytes.
immunoglobulin g's the genes coding for immunoglobulin heavy and light chains, which are organized in three loci coding for κ light chains, λ light chains, and heavy chains.
K-ras gene a type of oncogene.
lethal gene one whose presence brings about the death of the organism or permits survival only under certain conditions.
major gene a gene whose effect on the phenotype is always evident, regardless of how this effect is modified by other genes.
mutant gene one that has undergone a detectable mutation.
operator gene one serving as a starting point for reading the genetic code, and which, through interaction with a repressor, controls the activity of structural genes associated with it in the operon.
gene pool all of the genes possessed by all of the members of a population that will reproduce.
recessive gene one that produces an effect in the organism only when it is transmitted by both parents, i.e., only when the individual is homozygous. See also heredity.
regulator gene (repressor gene) one that synthesizes repressor, a substance which, through interaction with the operator gene, switches off the activity of the structural genes associated with it in the operon.
sex-linked gene a gene carried on a sex chromosome (X or Y); only X linkage has clinical significance. See X-linked gene.
structural gene one that forms templates for messenger RNA and is thereby responsible for the amino acid sequence of specific polypeptides.
tumor suppressor gene a gene whose function is to limit cell proliferation and loss of whose function leads to cell transformation and tumor growth; called also antioncogene.
X-linked gene a gene carried on the X chromosome; the corresponding trait, whether dominant or recessive, is always expressed in males, who have only one X chromosome. the term “X-linked” is sometimes used synonymously with “sex-linked,” since no genetic disorders have as yet been associated with genes on the Y chromosome.

le·thal gene

a gene that produces a genotype that leads to death of the organism before reproduction is possible or precludes reproduction; for a recessive gene the homozygous or hemizygous state is lethal.

le·thal gene

(lē'thăl jēn)
A gene that produces a genotype that leads to death of the organism before reproduction is possible or that precludes reproduction; for a recessive gene the homozygous or hemizygous state is lethal.

lethal gene

a gene whose effect on the PHENOTYPE is sufficiently drastic to kill the individual. Death from lethal genes may occur at any time from fertilization of the egg to advanced age. Lethal genes can be either dominant (e.g. HUNTINGTON'S CHOREA, a progressive nervous disorder which occurs usually around middle age) or recessive (e.g. SICKLE-CELL ANAEMIA, a disorder of HAEMOGLOBIN causing death in adolescence).
References in periodicals archive ?
Because of lethal gene, negative selection system does TOPO(r) cloning vector weretransferred into expression vector, pIPKb002 which contains suitable recombination sites (attR1 and attR2) for Gateway cloning (Fig.
Martin knew she had the same potentially lethal gene that prompted her famous niece to have the operation on her breasts.
arboreum may be the result of cumulative effect of less number of lethal genes of diploid AA genome.
The compositions are DNA constructs that comprise novel arrangements of T-DNA molecules containing genes of interest, positive selectable marker genes, and conditional lethal genes. The methods disclosed herein comprises transforming a plant cell to comprise the DNA constructs of the present invention, regenerating the plant cell into a plant and identifying independant transgene loci, where the selectable marker genes or transgenic elements can be segregated in the progeny.