Gain-of-function mutation
A mutation that confers a new property on a protein, causing a new phenotype.
Gamete
Mature reproductive cell that is specialized for sexual fusion. Each gamete is haploid and fuses with a cell of similar origin but of opposite sex to produce a diploid zygote. Gametic disequilibrium deviations from what is expected of loci that assort independently as a result of hybridization, genetic drift, and migration. Gametogenesis the formation of male and female gametes.
Gametophyte
The haploid sexual generation in the life cycle of plants that produces the gametes by mitotic division of spores.
Gc box
A promoter-proximal element upstream of the promoter of a eukaryotic gene at about 90 bp away from the transcription start site. The gc box has the consensus sequence 5’-gggcgg–3’.
Gene
The physical and functional unit that helps determine the traits passed on from parents to offspring; also called mendelian factor. In molecular terms, a gene is a nucleotide sequence in DNA that specifies a polypeptide or RNA. Alterations in a gene’s sequence can give rise to species and individual variation.
Gene conversion
A nonreciprocal recombination process in which one allele in a heterozygote is changed to the other allele, thus converting a heterozygous genotype to a homozygous genotype.
Gene expression
The overall process by which a gene produces its product and the product carries out its function.
Gene flow
The movement of genes that takes place when organisms migrate and then reproduce, contributing their genes to the gene pool of the recipient population.
Gene markers
Alleles that produce detectable phenotypic differences useful in genetic analysis.
Gene mutation
A heritable alteration in the sequence of a gene, usually from one allele form to another, or in the sequences regulating the gene.
Gene pool
All of the alleles in a breeding population existing at a given time.
Generalized transduction
A type of transduction in which any gene may be transferred from one bacterium to another. General transcription factor (GTF) one of several proteins required for the initiation of transcription by a eukaryotic RNA polymerase.
Gene segregation
mendel’s first law stating that two members of a gene pair (alleles) segregate (separate) from each other during the formation of gametes. As a result, one-half the gametes carry one allele and the other half carry the other allele.
Gene silencing
Inactivation of a gene due to its location in the genome, DNA methylation, or RNA interference (rnai). This type of gene control often represses transcription of multiple genes in a region of DNA.
Genetic code
The set of three-nucleotide sequences (codons) within mRNA that carries the information for specifying the amino acid sequence of a polypeptide.
Genetic correlation
Phenotypic correlation due to genetic causes such as pleiotropy or genetic linkage.
Genetic counselling
Evaluation of the probabilities that prospective parents will have a child who expresses a particular genetic trait (deleterious or not) and discussion with the couple of their options for avoiding or minimizing the possible risk.
Genetic drift
Random change in allele frequencies within a population over time; observed most often in small populations due to sampling error.
Genetic engineering
Alteration of the genetic constitution of cells or individuals by directed and selective modification, insertion, or deletion of an individual gene or genes.
Genetic hitchhiking
During the process in which an allele that is advantageous or detrimental and thus is a target of natural selection may sweep to fixation or be lost very rapidly in the population, variants that are selectively neutral, or nearly so, and lie in positions on the chromosome nearby a new mutation may hitchhike along with the mutation to fixation or loss.
Genetic map
A representation of the relative distances separating genes on a chromosome based on the frequencies of recombination between nonallelic gene loci; also called linkage map.
Genetic marker
Any gene or DNA region whose sequence varies among individuals and is useful in genetic analysis, for example, in the detection of genetic recombination events.
Genetic recombination
A process by which parents with different alleles give rise to progeny with genotypes that differ from either parent. For example, parents with a b and a b genotypes can produce recombinant progeny with a b and a b genotypes.
Genetics
The science that deals with the structure and function of genes and their transmission from one generation to the next (heredity).
Genetic structure of populations
The patterns of genetic variation found among individuals within groups.
Genetic testing
Analysis to determine whether an individual who has symptoms of a particular genetic disease or is at high risk of developing it actually has a gene mutation associated with that disease.
Genetic variance (vg)
Component of the phenotypic variance for a trait that is due to genetic differences among individuals in a population. Vg includes variation arising from the dominance effects of alleles, the additive effects of genes, and epistatic interactions among genes.
Gene tree a phylogenetic tree
Based on the divergence observed within a single homologous gene. Gene trees are not always a good representation of the relationships among species because polymorphisms in any given gene may have arisen before speciation events.
Genic sex determination
System of sex determination, found primarily in eukaryotic microorganisms, in which sex is determined by different alleles at a small number of gene loci.
Genome
The total amount of genetic material in a chromosome set; in eukaryotes, this is the amount of genetic material in the haploid set of chromosomes of the organism.
Genomic imprinting
Phenomenon in which the phenotypic expression of certain genes is determined by whether a particular allele is inherited from the female or male parent.
Genomic library
Collection of cloned dna fragments in which every dna sequence in the genome of an organism is represented at least once.
Genomics
The development and application of new mapping, sequencing, and computational procedures to analyze the entire genome of organisms.
Genotype
The complete genetic makeup (allele composition) of an organism. The term is commonly used in reference to the specific alleles present at just one or a limited number of genetic loci.
Genotype frequency
Percentage of individuals within a population that have a particular genotype. The sum of the genotype frequencies at a given locus is 1.
Genotypic sex determination
Any system in which sex chromosomes play a decisive role in the inheritance and determination of sex.
Germ-line mutation
In sexually reproducing organisms, a change in the genetic material in germ-line cells (those that give rise to gametes), which may be transmitted by the gametes to the next generation, giving rise to an individual with the mutant genotype in both its somatic and germline cells.
Glucose effect
The inactivation of some inducible operons in the presence of glucose even though the operon’s inducer is present.
Goldberg–hogness box
a part of the core promoter in eukaryotic genomes; it is located about 30 base pairs upstream from the transcription start point. Also called as TATA Box.
Guanine (g)
A purine found in RNA and DNA. In double stranded DNA, guanine pairs with cytosine, a pyrimidine, by hydrogen bonding.
