Lethal genes in snapdragons having three types of plants : (green, yellowish green and white)
Answers
Answer:
It has been observed that all genes or genetic factors are not useful to the organism. There are some genetic factors or genes, when present in any organism cause its death during early stage of development. They may even cause death of the individual either in homozygous dominant or homozygous recessive condition.
A French geneticist L. Cuenot (1905) reported on the inheritance of mouse body colour. He found that “yellow” body colour was dominant over normal “brown” colour and was governed by single gene “Y”. It was observed that yellow mice could never be obtained in homozygous condition.
Explanation:
It has been observed that all genes or genetic factors are not useful to the organism. There are some genetic factors or genes, when present in any organism cause its death during early stage of development. They may even cause death of the individual either in homozygous dominant or homozygous recessive condition.
When yellow coated mice was crossed with another yellow coated mice, segregation for yellow and brown body colour was obtained in 2: 1 ratio. The brown individuals were pure and homozygous where as yellow individuals were heterozygous. These results may be explained on the assumption that the dominant allele for yellow body colour is lethal in homozygous condition.
(Inheritance of yellow coated colour in mice. Mice with yellow coated colour are always heterozygous.)