The genotypes and phenotypes of all potential

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Unformatted text preview: ali o “mendeliani” Testcross results random fertilization events. The genotypes and phenotypes of all potential offspring are ascertained by reading the entries in the boxes. The Punnett square method is particularly useful when you are first learning about genetics and how to solve problems. Note the ease with which the 3:1 phenotypic ratio and the 1:2:1 genotypic ratio is derived in the F2 generation in Figure 3–3. (a) • Caratteri Autosomici Dominanti (b) dd Dd dd Homozygous dwarf Heterozygous tall Homozygous dwarf DD Homozygous • Caratteri Autosomici Recessivi tall • Caratteri legati al Cromosoma X • Dominanti D d D d d The Testcross: One Character • Recessivi Tall plants produced in the F 2 generation are predicted to be either the DD or Dd genotype. You might ask if there is a way to distinguish the genotype. Mendel devised a rather simple method that is still used today in breeding plants and animals: the testcross. The organism expressing the dominant phenot...
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