Question

Please explain in details one good reason for making DNA from a cross progeny

Answer 1

One good and most important reason for making DNA from a cross progeny is to determine the parental genotype. Mendel performs many test cross of a hybrid progeny (genotypically heterozygous- having parental genes), mendel stated that hybrid progeny would make two kind of gamates in each equal frequencies, for each heterozygous traits, resulting in two type of monohybrid, four types of dihybrid and eight types of trihybrid crosses.

mendel introduces the notion of crossing individuals with one pure plants (recessive traits) with F1 generation. he found interesting results in all three types of hybridisation

1- monohybrid test cross ratio- 1:1

2- dihybrid test cross ratio 1:1:1:1

3- trihybrid test cross ratio- 1:1:1:1:1:1:1:1

currently test crosses are done widely to simply the analysis of progeny from their parental , those who are heterozygous for many genes, such as - linkage and gene mapping

linkage means two genes are located very near to each other, by this we can figure out whether the crossing over has taken place or not, if the crossing over is not done, then will get generation only, no recombinant will be produced.

crossing over is the physical exchange of chromosomes when they get crossed during meiosis 1,