Flower Parts

Genotype

A genotype is an individual's collection of genes. The term also can refer to the two alleles inherited for a particular gene. The genotype is expressed when the information encoded in the genes' DNA is used to make protein and RNA molecules. The expression of the genotype contributes to the individual's observable traits, called the phenotype.

Phenotype

A phenotype is an individual's observable traits, such as height, eye color, and blood type. The genetic contribution to the phenotype is called the genotype. Some traits are largely determined by the genotype, while other traits are largely determined by environmental factors.

Trait

A trait is a specific characteristic of an organism. Traits can be determined by genes or the environment, or more commonly by interactions between them. The genetic contribution to a trait is called the genotype. The outward expression of the genotype is called the phenotype.

Allele

An allele is one of two or more versions of a gene. An individual inherits two alleles for each gene, one from each parent. If the two alleles are the same, the individual is homozygous for that gene. If the alleles are different, the individual is heterozygous. Though the term "allele" was originally used to describe variation among genes, it now also refers to variation among non-coding DNA sequences.

Codominance

Codominance is a relationship between two versions of a gene. Individuals receive one version of a gene, called an allele, from each parent. If the alleles are different, the dominant allele usually will be expressed, while the effect of the other allele, called recessive, is masked. In codominance, however, neither allele is recessive and the phenotypes of both alleles are expressed.

Dominant

Dominant refers to the relationship between two versions of a gene. Individuals receive two versions of each gene, known as alleles, from each parent. If the alleles of a gene are different, one allele will be expressed; it is the dominant gene. The effect of the other allele, called recessive, is masked.

Genetic linkage

Genetic linkage is a term which describes the tendenc of certian loci or alleles to be inhertied together.

Heterozygous

Heterozygous refers to having inherited different forms of a particular gene from each parent. A heterozygous genotype stands in contrast to a homozygous genotype, where an individual inherits identical forms of a particular gene from each parent.

Homozygous

Homozygous is a genetic condition where an individual inherits the same alleles for a particular gene from both parents.

Hybrid

Hybridization is the process of combining two complementary single-stranded DNA or RNA molecules and allowing them to form a single double-stranded molecule through base pairing. In a reversal of this process, a double-stranded DNA (or RNA, or DNA/RNA) molecule can be heated to break the base pairing and separate the two strands. Hybridization is a part of many important laboratory techniques such as polymerase chain reaction and Southern blotting.

Testcross

It is a cross between a orgainsim whose genotype for a certian trait is unkown and a organism that is homozygous recessive for that triat.

Punnett square

It is a diagram that is used to predict an outcome of a particular cross or breeding experiment.

Dihybrid cross

It is hybridzation using two traits with two alleles each.

Monohybrid cross

It is hybridzation usng a single trait with two alleles.

Recessive

Recessive is a quality found in the relationship between two versions of a gene. Individuals receive one version of a gene, called an allele, from each parent. If the alleles are different, the dominant allele will be expressed, while the effect of the other allele, called recessive, is masked. In the case of a recessive genetic disorder, an individual must inherit two copies of the mutated allele in order for the disease to be present

Sex-linked gene

Sex linked is a trait in which a gene is located on a sex chromosome. In humans, the term generally refers to traits that are influenced by genes on the X chromosome. This is because the X chromosome is large and contains many more genes than the smaller Y chromosome. In a sex-linked disease, it is usually males who are affected because they have a single copy of X chromosome that carries the mutation. In females, the effect of the mutation may be masked by the second healthy copy of the X chromosome.

Chromosome theory of inheritance

The chromosome theory of inheritance is a fundamental unifying theory of genetics with identifies chromosomes as the carrier of genetic material.

Cross-fertilization

The feritilization by the union of male and femal gametes from different individuals of the same species.

Intermediate inheritance

The inheritance in which the phenotype of the heterozygote falls between that of either homozygote.

Polygenic inheritance

The inheritance of quantitative traits or polygenic inheritance refers to teh inheritance of a phenotypic characteristic that varies in degree and can be attributed to teh interactions between two or more genes and their environment.

Gene locus

The specific place on a chromosome where a gene is located.

Genetics

The study of heredity and the variation of inherited characteristics.