Genetic Terms

Allele: one of two or more different versions of the same gene.

Chromosome: a coiled structure made of DNA and proteins containing sister chromatids, which form a cell's genetic material and go through cell division. 

Codominance: relationships between two alleles for the same gene in which both alleles are expressed equally in the phenotype of the heterozygote. 

Cross Fertilization: the process in which the sperm from one organism fertilizes the egg of another organism. This usually occurs between two different individuals of the same species. It's a way to increase genetic diversity, as the offspring inherit a mix of genes from both parents. 

Dihybrid Cross: a cross between F1 offspring of two individuals that differ in two traits of particular interest. 

Dominant: referring to an allele that masks the presence of another allele (called recessive) for the same gene when both alleles are present in a heterozygote; or referring to a trait controlled by such an allele. WRITTEN AS A CAPITAL LETTER AND IS EXPRESSED WHEN PRESENT

Genetic Linkage: refers to the tendency of genes that are located close to each other on the same chromosome to be inherited together during meiosis. This happens because the genes are physically linked and less likely to be separated by recombination, which is the process where chromosomes exchange segments. 

Gene: a portion of DNA strand that codes for a protein.

Genetics: the study or science of heredity

Genotype: alleles an individual inherits at a particular genetic locus. 

Heterozygous: an organism that inherits two different alleles for a given gene. One is dominant and the other is recessive, so Ll or Gg Aa

Homozygous: an organism that inherits two alleles of the same type for a given gene. 

Hybrids: offspring that results from a cross between two different types of parents. 

Intermediate Inheritance (INCOMPLETE DOMINANCE): relationship between the alleles for a gene in which one allele is only partly dominate to the other allele so an intermediate phenotype results. 

Locus: is the position of a gene on a chromosome.

Monohybrid Cross: is a genetic mix between two individuals who have different alleles at one genetic locus of intrest 

• Helps see how traits are passed down

Phenotype: characteristics of an organism that depend on how the organisms genotype is expressed

Polygenic (characteristics): characteristics, or traits, controlled by more than one gene, each of which may have two or more alleles. 

Punnett Square: chart for determining the expected percentages of different genotypes in the offspring of two parents 

Recessive: allele that is masked by the presence of another allele for the same gene when they occur together in a heterozygote. If both alleles are recessive it will be present and homozygous. 

Sex-Linked: 

• Gene located on a sex chromosome 

• Trait controlled by a gene located on a sex chromosome 

Testcross: genetic experiment used to determine the genotype of an individual showing a dominant trait. This is done by crossing the individual with another individual that is homozygous recessive for the trait in question. 

Trait: is a specific characteristic or feature of an organism. They can be physical like eye color or height or behavioral like how animals hunt or communicate. They are often inherited from their parent.