Recessiivisia

Recessiivisia is a term used in genetics to describe a particular type of gene allele. An allele is a variant form of a gene. For a trait to be expressed when a recessive allele is present, an individual must inherit two copies of that recessive allele, one from each parent. If an individual inherits one dominant allele and one recessive allele, the dominant allele will typically mask the expression of the recessive allele, and the individual will exhibit the trait associated with the dominant allele.

The concept of recessiveness is fundamental to understanding Mendelian inheritance. Gregor Mendel's experiments with pea plants were crucial in establishing these principles. For instance, if a gene for flower color has a dominant allele for purple (P) and a recessive allele for white (p), a plant with the genotype PP or Pp will have purple flowers. Only a plant with the genotype pp will have white flowers.

Recessive alleles can persist in a population even if they are not phenotypically expressed in every generation. Carriers are individuals who possess one copy of a recessive allele but do not display the associated trait because they also have a dominant allele. These carriers can pass the recessive allele to their offspring. Certain genetic disorders, such as cystic fibrosis and sickle cell anemia, are inherited in an autosomal recessive pattern, meaning that an affected individual must inherit two copies of the recessive allele.