Punnett Squares - 1 because the P 1 plants were true...

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Punnett Squares Suppose that an "Aa" individual is crossed with another "Aa" individual. One will produce "A" eggs and "a" eggs. The other will produce "A" sperm and "a" sperm. What are all of the possible combinations of eggs and sperm? A Punnett square can be used to show all of these combinations. The Punnett square in the diagram below is used to show between two Aa individuals. The square below is used for this cross: AA X Aa. One half of the offspring produced by this cross will be AA, the other half will be Aa. The cross can also be written as shown below because the AA parent can produce only one kind of gamete (all A). A Closer look at Mendel’s Crosses (One Gene Locus) Y = yellow y = green P 1 YY X yy F 1 Yy Yy X Yy A cross between two individuals that are heterozygous for a trait is called a monohybrid cross . F 2 The above cross is illustrated below. Genotype and Phenotype The genetic makeup of P 1 plants was different from that of F
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Unformatted text preview: 1 because the P 1 plants were true breeding and the F 1 plants were not. The genetic makeup of an individual is referred to as its genotype . Because the plants are diploid, two letters can be used to write the genotype. In this case, the genotype of the P 1 plants was YY; the genotype of the F 1 plants was Yy. The characteristics of an individual are its phenotpye . This word refers to what the individual looks like so ddjectives are used to write the phenotype. For example, "yellow" or "tall" are phenotypes. The yellow P 1 plants looked like the F 1 ; they had the same phenotype but different genotypes. An individual with a recessive phenotype has two recessive genes. A dominant phenotype results from either one or two dominant genes. In the cross above, YY or Yy are yellow; yy is green. The phenotype ratio in the F2 is 3 yellow:1 green. The genotype ratio is 1YY:2Yy:1yy. Genotype Phenotype AA or Aa Yellow aa Green...
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Punnett Squares - 1 because the P 1 plants were true...

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