Dominant gene


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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.

dom·i·nance of traits

an expression of the apparent physiologic relationship existing between two or more genes that may occupy the same chromosomal locus (alleles). At a specific locus there are three possible combinations of two allelic genes, A and a: two homozygous (AA and aa) and one heterozygous (Aa). If a heterozygous individual presents only the hereditary characteristic determined by gene A, but not a, A is said to be dominant and a recessive; in this case, AA and Aa, although genotypically distinct, should be phenotypically indistinguishable. If AA, Aa, and aa are distinguishable, each from the others, A and a are codominant.

dom·i·nance of traits

(dom'i-năns trāts)
An expression of the apparent physiologic relationship existing between two or more genes that may occupy the same chromosomal locus (alleles). At a specific locus there are three possible combinations of two allelic genes, A and a: two homozygous (AA and aa) and one heterozygous (Aa). If a heterozygous individual presents only the hereditary characteristic determined by gene A, but not a, A is said to be dominant and a recessive; in this case, AA and Aa, although genotypically distinct, should be phenotypically indistinguishable. If AA, Aa, and aa are distinguishable, each from the others, A and a are codominant.

gene

(jen) [Ger. Gen, ult. fr Gr. genos, kind, race, descent]
Enlarge picture
AUTOSOMAL DOMINANT INHERITANCE
Enlarge picture
AUTOSOMAL DOMINANT INHERITANCE
The basic unit of heredity, made of DNA, the code for a specific protein. Each gene occupies a certain location on a chromosome. Genes are self-replicating sequences of DNA nucleotides, subject to random structural changes (mutations). Hereditary traits are controlled by pairs of genes in the same position on a pair of chromosomes. These alleles may be either dominant or recessive. When both pairs of an allele are either dominant or recessive, the individual is said to be homozygous for the traits coded by the gene. If the alleles differ (one dominant and one recessive), the individual is heterozygous. See: illustration; chromosome; DNA; RNA

autosomal dominant gene

A dominant gene that is found on any chromosome other than the X or Y chromosome.

autosomal recessive gene

A recessive gene that is found on any chromosome other than the X or Y chromosome.

BRCA1 gene

A breast cancer gene found in a small percentage of patients with this malignancy, and carried by some individuals who will develop breast cancer later in life.

Patient care

BRCA1 Gene Mutation: Patient care focuses on determining the family history of the patient and referral to a genetic counselor with expertise in this mutation when appropriate.

BRCA2 gene

A breast cancer gene found in a small number of patients with breast and ovarian cancers, and carried by some individuals who will develop breast cancer later in life.

complementary genes

Nonallelic, independently located genes, neither of which will be expressed in the absence of the other.

cystic fibrosis transmembrane conductance regulator gene

The gene that codes for a protein that regulates the movement of ions, esp. chloride, across cell membranes.

dominant gene

See: dominant

histocompatibility gene

One of the genes composing the HLA complex that determines the histocompatibility antigenic markers on all nucleated cells. These genes create the antigens by which the immune system recognizes “self” and determines the “nonself” nature of pathogens and other foreign antigens. These antigens are crucial determinants of the success or failure of organ transplantation.
See: histocompatibility locus antigen

holandric gene

A gene located in the nonhomologous portion of the Y chromosome of males.

homeobox gene

Any transcription factor that regulates the growth, differentiation, replication, and movement of cells in the body. These genes influence both normal and abnormal embyological development and the development or suppression of malignant tumors.

housekeeping gene

A gene expressed in nearly every cell and every tissue of an organism, i.e., one that encodes a protein fundamental to cellular activity throughout the organism.

immune response gene

One of the many genes that control the ability of leukocytes to respond to specific antigens.
See: antigen; B cell; HLA complex; T cell

inhibiting gene

A gene that prevents the expression of another gene.

interleukin-28B gene

A genetic variant that increases the likelihood of having a favorable to response to antiviral treatment for chronic hepatitis C, genotype 1 infection (traditionally the most resistant hepatitis C genotype).

lethal gene

A gene that creates a condition incompatible with life and usually results in the death of the fetus.

modifying gene

A gene that influences or alters the expression of other genes.

mutant gene

An altered gene that permanently functions differently than it did before its alteration.

operator gene

A gene that controls the expression of other genes.
See: operon

gene p53

A gene thought to be important in controlling the cell cycle, DNA repair and synthesis, and programmed cell death (apoptosis). Mutations of p53 have occurred in almost half of all types of cancer, arising from a variety of tissues. Mutant types may promote cancer. The normal, wild-type gene produces a protein important in tumor suppression.

pleiotropic gene

A gene that has multiple effects.

posttranscriptional gene silencing

RNA interference.

presenilin gene

Rare traits responsible for early-onset Alzheimer's disease.

RB gene

Tumor suppressor gene encoding for the retinoblastoma (RB) protein, mutations of which are associated with various human tumors, including retinoblastoma, osteosarcoma, some leukemias, and some adenocarcinomas.
See: tumor suppressor gene; retinoblastoma

recessive gene

A trait that is not expressed unless it is present in the genes received from both parents. A recessive trait may be apparent in the phenotype only if both alleles are recessive.
Synonym: recessive characteristic

regulator gene

A gene that can control some specific activity of another gene.

sex-linked gene

Sex-linked characteristic.

structural gene

A gene that determines the structure of polypeptide chains by controlling the sequence of amino acids.

susceptibility gene

A gene that increases a person's likelihood of contracting a heritable illness.

tumor suppressor gene

A gene that suppresses the growth of malignant cells.
See: cancer

X-linked gene

A gene on the X chromosome for which there is no corresponding gene on the Y chromosome. X-linked genes (e.g., the gene for red-green color blindness) are expressed but in males even these genes are recessive because there is no correponding gene to dominate them.

Dominant gene

A gene, whose presence as a single copy, controls the expression of a trait.
Mentioned in: Genetic Testing

gene

the unit of heredity most simply defined as a specific segment of DNA, usually in the order of 1000 nucleotides, that specifies a single polypeptide. Many phenotypic characteristics are determined by a single gene, while others are multigenic. Genes are specifically located in linear order along the single DNA molecule that makes up each chromosome. All eukaryotic cells contain a diploid (2n) set of chromosomes so that two copies of each gene, one derived from each parent, are present in each cell; the two copies often specify a different phenotype, i.e. the polypeptide will have a somewhat different amino acid composition. These alternative forms of gene, both within and between individuals, are called alleles. Genes determine the physical (structural genes), the biochemical (enzymes), physiological and behavioral characteristics of an animal.
The formation of gametes (sperm, ova) involves a process of meiosis, which allows crossing over between four pairs of chromosomes, two derived from each parent, which means that new forms of a particular chromosome are created. Gamete formation also results in cells (gametes) with a haploid (n) set of chromosomes that in fertilization creates a new individual, which is a recombinant of 2n chromosomes, half derived by way of the ovum from the mother and half via the spermatozoa from the father.
Changes in the nucleotide sequence of a gene, either by substitution of a different nucleotide or by deletion or insertion of other nucleotides, constitute mutations which add to the diversity of animal species by creating different alleles and can be used as a basis for genetic selection of different phenotypes. Some mutations, be they a single base change in a single gene or a major deletion, are lethal.

gene action
the way in which genes exert their effects on tissues or processes, e.g. by being dominant or recessive, or partially so, being absent, being sex-linked, being involved in chromosomal aberrations.
allelic g's
different forms of a particular gene usually situated at the same position (locus) in a pair of chromosomes.
gene amplification
see gene duplication (below).
gene bank
the collection of DNA sequences in a given genome. Called also gene library.
barring gene
responsible for the barred pattern on the feathers of Barred Plymouth Rock birds.
gene box
see box (4).
gene clone
see clone.
gene cluster
a group of related genes derived from a common ancestral gene, located closely together on the same chromosome. Called also multigene family.
complementary g's
two independent pairs of nonallelic genes, neither of which is functional without the other.
gene conversion
a non-reciprocal exchange of DNA elements during meiosis which results in a functional rearrangement of chromosomal DNA.
dhfr gene
dihydrofolate reductase gene; an enzyme required to maintain cellular concentrations of H2 folate for nucleotide biosynthesis, and which has been used as a 'selective marker'; cells lacking the enzyme only survive in media containing thymidine, glycine and purines; mutant cells (dhfr) transfected with DNA that is dhfr′ can be selectively grown in medium lacking these elements.
diversity (D) gene
genes located in diversity (D) segment; contribute to the hypervariable region of immunoglobulins.
dominant gene
one that produces an effect (the phenotype) in the organism regardless of the state of the corresponding allele. Examples of traits determined by dominant genes are short hair in cats and black coat color in dogs.
gene duplication
as a result of non-homologous recombination, a chromosome carries two or more copies of a gene.
gene expression
gene frequency
the proportion of the substances or animals in the group which carry a particular gene.
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 (MHC) that govern the immune response to individual immunogens.
jumping gene
see mobile dna.
gene knockout
replacement of a normal gene with a mutant allele, as in gene knockout mice.
lethal gene
one whose presence brings about the death of the organism or permits survival only under certain conditions.
gene library
see gene bank (above).
gene locus
see locus.
mutant gene
one that has undergone a detectable mutation.
non-protein encoding gene
the final products of some genes are RNA molecules rather than proteins.
overlapping g's
when more than one mRNA is transcribed from the same DNA sequence; the mRNAs may be in the same reading frame but of different size or they may be in different reading frames.
gene pool
total of all genes possessed by all members of the population which are capable of reproducing during their lifetime.
gene probe
see probe (2).
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.
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.
reporter gene
one that produces products which can be measured and therefore used as an indicator of whether a DNA construct has successfully been transferred.
sex-linked gene
one that is carried on a sex chromosome, especially an X chromosome.
gene splicing
structural gene
nucleotide sequences coding for proteins.
gene therapy
the insertion of functional genes into cells of the host in order to alter its phenotype, usually used to treat an inherited defect.
gene transcription
gene transfer
tumor suppressor g's
a class of genes that encode proteins that normally suppress cell division that when mutated allow cells to continue unrestricted cell division and may result in a tumor.
References in periodicals archive ?
The results of this experiment indicate that resistance to RWA in the 'Azadi' cultivar is conditioned by one dominant gene.
A dominant gene is said to be "strong" and will always have influence over a "weaker" gene.
the answer would be even if they were few colored among them, they were indigenous African people; because black and black can produce any color but white and white can't produce a black color; in biologically the dominant genes can produce recessive genes, "the albino children everywhere in Africa" ; but recessive or weak genes can't produce the dominant genes; also having mixed pharaohs in middle kingdom would also be true since the foreigners continued invading Kemet Ethiopia or Egypt and continuously repelled by the indigenous populations.
The cause of the problem has to do with the increased probability of recessive genes being present in close blood relatives that present themselves as dominant genes that cause serious health problems in children of such unions, including cystic fibrosis, retinoblastoma, juvenile muscular dystrophy and more than 1,000 other identified recessive gene disorders.
Fingers crossed that hers are not dominant genes, then.
Professor Gareth Evans reviews the current understanding of high-risk predisposition gene carriers and puts in context the role played by high-penetrant autosomal dominant genes in breast cancer aetiology.
Dominant genes from one parent can cause offspring to have a trait that the parent had, like brown eyes.
The native plant, which is slightly smaller than the Spanish bluebell, has less dominant genes and its traits quickly disappear, he explained.
Two new lines of Drosophila melanogaster prove that it's possible to create insects with dominant genes that make females self-destruct on cue, report Dean D.
No evolutionary problem is caused by eliminating dominant genes that cause serious genetic disorders such as Huntington's disease.
It's a bold testament to the power of nature (not that nurture was ever going to be in the equation) and the triumph of dominant genes.
The ability of siRNAs to knock down disease-causing proteins coded by dominant genes offers hope for new and effective treatment of diseases that other genetic engineering strategies--such as gene replacement therapy--can not address.