Recessive means in genetics " receding " or " not kicking in appearance." In genetics, a distinction between dominant and recessive alleles of a gene. A dominant allele is located in the characteristic value against a recessive allele through. In order for a recessive allele can be dominant trait, it must be homozygous or occur together with another recessive allele.
The recessive allele is mostly caused by a mutation, and may result in a feature with reduced functionality. When present heterozygous, can the non-defective ( wild-type ) allele dub the possible impairment and compensate for the deficiency of a defective allele.
In addition, there is the co-dominant and X-linked inheritance.
- If a person has in his possession both the hereditary factor for blood group B property as well as on the sister chromatid for 0, so it carries blood group B, as the blood group 0 compared with B recessive behaves. Or the other way around: because B is dominant, it continues in the characteristic value against the recessive allele by 0. Blood group A is also dominant to 0, which means that blood group 0 only occurs if they are on both chromosomes 0 alleles. A and B are co-dominant, however: people who wear an A and a B allele, show both blood groups of A and B, which is why there is blood group AB.
- In pea ( Pisum sativum ), there are plants with red flowers and one with white flowers. For the flower color a gene with two different alleles is responsible: one allele codes for red color, the other for white flower color. As in diploid organisms such as the pea plant always two alleles occur that determine a characteristic, the plant can two identical alleles for the red flower color, two identical alleles of the white flower color or two different alleles (one for red and one for the white flower color ) possess. The latter is the so-called heterozygosity, and in the case of the pea plant carrying the red flowers, because the red color, which is encoded by an allele of the other allele of the white masked simply. Suppose you observed in the same conditions, a rose bloom in the heterozygous plants, the corresponding pattern of inheritance is called intermediate.