Genotype: Arrangement of genes in an organism.
Genome: All a cell's genes.
Phenotype: External appearance of an organism.
Allele: One form of a gene:
- Wild type-Allele: The normal form of a gene, as it usually appears
in nature. In Helix pomatia: The dextral form.
- Dominant / Recessive: In the heterozygote genotype the dominant
allele suppresses the recessive one, so it may not be seen in the phenotype.
Only in a homozygote constellation the recessive allele can be seen also in
- The both alleles of a gene in a cell (one from the sperm cell and one from the egg
cell) are different.
- The both alleles of a gene in a cell (see above) are the same. Only that way also
recessive alleles can be expressed.