rfrfr2r2 (White) RIRIRZR2 х (Dark red) RirtR2r2 (Intermediate red) Self-fertilization RIR2 R1:2 rIR2 rir2 RIRIRZR2 RIRIRZ12 RirIR2R2 RirIR2r2 RIR2 Intermediate red Dark red Medium red Medium red RIRIR212 RIRIr2r2 RirIR2r2 Rirtr2r2 Rir2 Intermediate Intermediate red Medlum red Light red red RirIRZR2 RirIRZr2 rfrfRZR2 rfrIR2r2 rMR2 Intermediate Intermediate red Medlum red Light red red RirIR2r2 Rirtr2r2 rirMR2r2 rfrtr2r2 rir2 Intermediate red Light red Light red White (a) Red and white hulls of wheat (b) Inheritance of hull color in wheat FIGURE 28.3 The Nilsson-Ehle experiment on how continuous variation is rekated to polygenic inheritance in wheat. (a) Red (top) and white (bottom) varieties of wheat, Triricum aestivum. (b) Nilsson-Ehle carefully categorized the colors of the hulls in the F2 generation and discovered that they followed a 1:4:6:4:1 ratio. This pattern occurs because the contributions of the red alkles are additive. Genes-Tralts In this example, two genes, each with two alleles (red and white), govern hull color. Offspring can display a range of colors, depending on how many cop- ies of the red allele they inherit. If an offspring is homozygous for the red allele of both genes, it will have dark red hulls. By comparison, if it carries three red alleles and one white allele, it will be medium red (which is not quite as deep in color). Thus, this quantitative trait can exhibit a range of phenotypes from dark red to white. (a): (top): O Nigel Cattlin/Science Source; (bottom): O irin-k/agetotostock RF
rfrfr2r2 (White) RIRIRZR2 х (Dark red) RirtR2r2 (Intermediate red) Self-fertilization RIR2 R1:2 rIR2 rir2 RIRIRZR2 RIRIRZ12 RirIR2R2 RirIR2r2 RIR2 Intermediate red Dark red Medium red Medium red RIRIR212 RIRIr2r2 RirIR2r2 Rirtr2r2 Rir2 Intermediate Intermediate red Medlum red Light red red RirIRZR2 RirIRZr2 rfrfRZR2 rfrIR2r2 rMR2 Intermediate Intermediate red Medlum red Light red red RirIR2r2 Rirtr2r2 rirMR2r2 rfrtr2r2 rir2 Intermediate red Light red Light red White (a) Red and white hulls of wheat (b) Inheritance of hull color in wheat FIGURE 28.3 The Nilsson-Ehle experiment on how continuous variation is rekated to polygenic inheritance in wheat. (a) Red (top) and white (bottom) varieties of wheat, Triricum aestivum. (b) Nilsson-Ehle carefully categorized the colors of the hulls in the F2 generation and discovered that they followed a 1:4:6:4:1 ratio. This pattern occurs because the contributions of the red alkles are additive. Genes-Tralts In this example, two genes, each with two alleles (red and white), govern hull color. Offspring can display a range of colors, depending on how many cop- ies of the red allele they inherit. If an offspring is homozygous for the red allele of both genes, it will have dark red hulls. By comparison, if it carries three red alleles and one white allele, it will be medium red (which is not quite as deep in color). Thus, this quantitative trait can exhibit a range of phenotypes from dark red to white. (a): (top): O Nigel Cattlin/Science Source; (bottom): O irin-k/agetotostock RF
Human Anatomy & Physiology (11th Edition)
11th Edition
ISBN:9780134580999
Author:Elaine N. Marieb, Katja N. Hoehn
Publisher:Elaine N. Marieb, Katja N. Hoehn
Chapter1: The Human Body: An Orientation
Section: Chapter Questions
Problem 1RQ: The correct sequence of levels forming the structural hierarchy is A. (a) organ, organ system,...
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