gene expression

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expression

 [eks-presh´un]
1. the aspect or appearance of the face as determined by the physical or emotional state.
2. the act of squeezing out or evacuating by pressure.
gene expression
1. the flow of genetic information from gene to protein.
2. the process, or the regulation of the process, by which the effects of a gene are manifested.
3. the manifestation of a heritable trait in an individual carrying the gene or genes that determine it.

gene ex·pres·sion

1. the detectable effect of a gene.
2. appearance of an inherited trait; for many genetic (for example, recessiveness, hypostasis, parastasis) and environmental (the absence of pertinent challenges) reasons, a gene may not be expressed at all. In those circumstances, it will have no impact on Darwinian evolution.

gene expression

the flow of genetic information from gene to protein; the process, or the regulation of the process, by which the effects of a gene are manifested; the manifestation of a heritable trait in an individual carrying the gene or genes that determine it.

gene expression

Genetics The process by which a gene's coded information is translated into the structures present and operating in the cell. See Gene, mRNA, Protein, RNA, Transcription, Translation, tRNA.

gene ex·pres·sion

(jēn eks-presh'ŭn)
1. The detectable effect of a gene.
2. Appearance of an inherited trait; for many reasons, a gene may not be expressed at all.

gene expression

the processes effecting the transfer of information encoded in the GENE to the functional gene product (PROTEIN or RNA). Generally, gene expression is equated with the processes of TRANSCRIPTION and TRANSLATION. However, where the gene product is RNA only transcription is involved. A gene that is expressed is an active gene.

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 ?
Differential expression of genes associated with lipid metabolism in longissimus dorsi of Korean bulls and steers.
In addition to a reduction in genes important for cognitive function, there was an elevated expression of genes that are associated with stress and repair mechanisms and genes linked to inflammation and immune responses.
New Brunswick, NJ, a biotechnology company using nutragenomics to develop wellness products from plants that alter the expression of genes responsible for human disease, has received $3 million in the form of equity capital, through a private offering of preferred stock, from venture-capital investors led by Amphion Capital Partners LLC, New York, NY.
are described for determining the level of expression of genes for specific types of PDGF receptor
Microarray analysis can elucidate the true nature of the "expressed genome" by confirming the expression of genes of unknown function.
Human Gene Therapy is an authoritative peer-reviewed journal published monthly in print and online that presents reports on the transfer and expression of genes in mammals, including humans.
2192172) are entitled "System for Expression of Genes in Plants," and include claims to methods for expressing one or more polynucleotides of interest using a set of plant viral vectors that function together.
Expression of genes hypothetically involved in the temperature adaptation will be also studied in different body tissues, after short and long term exposure to a temperature higher than natural.
Since microRNAs normally suppress the expression of genes, when a microRNA is overexpressed, the affected gene gets silenced.
Transformation of breast cells occurs through loss or mutation of tumor suppressor genes, or activation or amplification of oncogenes, leading to deregulation of signal transduction pathways, abnormal amplification of growth signals, and aberrant expression of genes that ultimately transform the cells into invasive cancer.
The authors report that higher urinary concentrations of phthalate metabolites were associated with reduced expression of genes involved in trophoblast differentiation, but exposures were not clearly associated with steroidogenesis gene expression.
In addition to decreasing the expression of certain oncogenes such as HER-2/neu, E1A also has been shown to increase the expression of genes that lead to cell death.