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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 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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- Fall '14