the set.
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Dominic Scott Kay And His Parents
Mendel limited only to breed plants that were distinguished by one character, but also carries out experiments with plants that differed in two characters. Here is another of the experiments carried out by Mendel.
A cross between plants that produce yellow seeds with plants that produce smooth and green and wrinkled seeds, in this If the purpose of the experiment was to see which of the characters, shape or color were inherited independently. The F1 generation is therefore to be all smooth alleles that determine the character is smooth and yellow should be dominant over green and wrinkled. As in experiments where individual characters were taken into account, even in this case Mendel let the plants grow and then let it fertilize, then counted the seeds of the F2 and classifies them according to the phenotype. As shown in the phenotypic classes were four, representing all possible combinations that could result from the parental characters, two of the four classes were identical to parental while others were completely different and that is wrinkled yellow, green and smooth.
The explanation is that each character was controlled by different genes each of the characters also had two alleles. and the two genes were inherited independently of each other.
When Mendel counted the F2 generation found to be precise:
Type Genotype Phenotype Number Value phenotypic
recombinant Y-rr , yellow, wrinkled 101 3/16 
Parentale yyrr verde, rough 32 1 / 16 Since the genes for color and shape of pea are assorted independently, the gamete can receive Y with equal probability l 'allele for the form R or r. Thus the presence of a particular allele of a gene, for example, the Y allele does not provide information sull'allele of the second gene. Each of the F1 dihybrid can produce four types of gametes: YR, Yr, yR, yr, this means in terms of the probability that the 1 / 4 of the eggs and 1 / 4 of the pollen will contain each of the four possible combinations. Another acute observation was that Mendel:
"... The different types of germ cells of a hybrid is produced, on average, in equal numbers." As shown in the Punnett square, at the time of fertilization, the four types of eggs, will be combined with any of the four types of pollen and this will lead to the formation of 16 different combinations, 16 possible zygotes. In reality we have only 9 at genotypic combinations: (YYRR, YYRr; YyRR; YyRr; yyRR; yyRr; YYrr; Yyrr; yyrr;). In turn, if we look genotypes we realize that we have only four phenotypes: smooth, yellow, green wrinkled, yellow wrinkled, green plain, in the ratio 9:3:3:1. And as predicted by Mendel's law of segegazione each character is inherited in an ever of 3:1 (if we observe only the shape or the color of pea). This means that the inheritance of the gene for the color of pea does not depend on the legacy of the gene for pea shape.
independent assortment : 
during the formation of gametes different pairs of alleles segregate independently of each other.
during the formation of gametes different pairs of alleles segregate independently of each other. 
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