Genetic Terms Used

Genotype: The combination of an organism's entire genome.

Genome: The entirety of genes in a cell or an organism.

Phenotype: Observable appearance of an organism.

Allele: Variant forms of a gene detected as different phenotypes, a variation of the same sequence of nucleotides at the same place on a long DNA molecule.

• Wildtyp-Allel: Genetic normal form usually present in natur: In Roman snails: dextral shell.
• Dominant / Rezessiv: In a heterozygous (mixed) genotype the dominant allele suppresses the recessive allele. The latter will only be expressed phenotypically with a homozygous genotype.

Heterozygous:

• Both alleles in a cell (one from each parent) are different.

Homozygous:

• Both alleles in a cell are equal. Only so the recessive allele can be expressed and be visible in the phenotype.