CYTO

• Allele


  One of two or more versions of a gene
• Codominance


  Relationship between two versions of a gene where neither allele is recessive and the phenotypes of both alleles are expressed
• Complete dominance


  Form of dominance in heterozygous condition where the dominant allele completely masks the effect of the recessive allele
• Dihybrid cross


  Mating experiment between two organisms that are identically hybrid for two traits
• Dominant


  Relationship between two versions of a gene where if the alleles are different, the dominant allele will be expressed
• Epistasis


  Circumstance where the expression of one gene is affected by the expression of one or more independently inherited genes
• Epistatic gene


  A gene that determines whether or not a trait will be expressed
• Expressivity


  The relative capacity of a gene to affect the phenotype of the organism
• F1 generation


  First filial generation, the first set of offspring from the parents
• F2 generation


  The result of a cross between two F1 individuals
• Gene


  The basic physical unit of inheritance
• Genotype


  An individual's collection of genes, can also refer to the two alleles inherited for a particular gene
• Heterozygous


  Having inherited different forms of a particular gene from each parent
• Homozygous


  The genetic condition where an individual inherits the same alleles for a particular gene from both parents
• Hypostatic gene


  A gene whose expression is masked by an epistatic gene
• Incomplete dominance


  Circumstance where the two copies of a gene for a particular trait combine so that neither dominates the other, creating a new phenotype
• Independent assortment


  The law stating that the random orientation of homologous chromosome pairs during metaphase I allows for the production of gametes with many different assortments of homologous chromosomes
• Locus


  Physical site or location of a specific gene on a chromosome
• Monohybrid cross


  Genetic mix between two individuals who have homozygous genotypes or heterozygous genotypes, used to observe how offspring express heterozygous genotypes
• P generation


  Organisms that were initially or originally crossed
• Penetrance


  Measures the proportion of individuals in a population who carry a specific gene and express the related trait
• Phenotype


  The observable physical properties of an organism
• Probability


  The likelihood or chance of an event occurring
• Punnett square


  A diagram used to predict the possible genotypes and phenotypes of the offspring of a cross

  
• Recessive


  Relationship between two versions of a gene where the recessive allele is only expressed when two copies are present
• Segregation


  The separation of alleles during gamete formation
• Sex-linked trait


  A trait determined by a gene located on a sex chromosome
• Testcross


  A cross between an individual of unknown genotype and an individual that is homozygous recessive for the trait being studied
• Penetrance


  Measures the proportion of individuals in a population who carry a specific gene and express the related trait. It is the relationship between a genotype and phenotype.
• Complete penetrance


  • All of the individuals in a population who carry a specific genotype express the corresponding phenotype
• Incomplete penetrance

  • Less than 100% of the individuals who bear a particular genotype express the corresponding phenotype
• Penetrance only describes whether or not individuals express a trait or not, and is not used to describe individual variations in the degree of expression of a particular gene, which is known as expressivity
• Probability


  The laws of probability are applicable to crossbreeding and are used to predict frequencies of specific genetic constitutions in offspring
• Punnett Square


  A graphical representation of the possible genotypes of an offspring arising from a particular cross or breeding event
• Recessive


  A trait that is expressed only when genotype is homozygous, and tends to be masked by other inherited traits, yet persists in a population among heterozygous genotypes
• Segregation


  The segregation of genes occurs during meiosis in eukaryotes, which is a process that produces reproductive cells called gametes. The Principle of Segregation describes how pairs of gene variants are separated into reproductive cells.
• Sex-linked trait


  A trait in which a gene is located on a sex chromosome, generally referring to traits influenced by genes on the X chromosome in humans because it is larger and contains more genes than the Y chromosome
• Testcross


  A genetic cross between a homozygous recessive individual and a corresponding suspected heterozygote to determine the genotype of the latter