Progress: Dihybrid crossing in Drosophila

Date: 2015-10-07; view: 456.

Organisms that contain two dominant genes (AA) or two recessive (aa), are called homozygous. Organisms containing one dominant and one recessive gene, called heterozygous (Aa). The first hybrid generation (F1), obtained by crossing of yellow and green seed peas, is heterozygous (Aa), as it contains the dominant gene of yellow color (A) and a recessive gene of green color (a). In the crossing between F1 animals second hybrid generation occurs, which is splitted among the features. This can be seen as follows.

Monohybrid CROSSING

Cross-breeding of two individuals that differ in one pair of allelomorphous genes, called monohybrid. An example of monohybrid crosses are Mendel's classical experiments with yellow seed and green seed peas. In the crossing of parental forms (P) yellow seed with green seed peas first hybrid generation has yellow seeds in F2. This is because the gene of yellow color of the seeds dominates above the gene of green color. Gene of green color of seeds is recessive in the relation to the gene of yellow color. Dominant are those genes that exert their action in the event that they are in somatic cells in the singular. Dominant genes are denoted by letter of the alphabet (the gene yellow color of pea - A). Recessive genes are those that exert their effect only if both of them have given individuals the same. Recessive genes indicated a small letter (a gene of pea green in color - a).

DIHYBRID CROSSING