Ch15 Diagrams

Ch15 Diagrams - Chapter 15 Diagrams Practice Exam Questions P Generation Yellow-round Green-wrinkled Starting with two true-breeding pea plants

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Chapter 15 Diagrams & Practice Exam Questions
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Figure 15.2 Yellow-round seeds ( YYRR ) Green-wrinkled seeds ( yyrr ) Meiosis Fertilization Gametes All F 1 plants produce yellow-round seeds ( YyRr ) P Generation F 1 Generation Meiosis Two equally probable arrangements of chromosomes at metaphase I LAW OF SEGREGATION LAW OF INDEPENDENT ASSORTMENT Anaphase I Metaphase II Fertilization among the F 1 plants 9 : 3 : 3 : 1 1 4 1 4 1 4 1 4 YR yr Yr yR Gametes Y R R Y y r r y R Y y r R y Y r R y Y r R Y r y r R Y y R Y r y R Y Y R R Y r y r Y R y r Y r Y r Y r Y R y R y R y r Y F 2 Generation Starting with two true-breeding pea plants, we follow two genes through the F 1 and F 2 generations. The two genes specify seed color (allele Y for yellow and allele y for green) and seed shape (allele R for round and allele r for wrinkled). These two genes are on different chromosomes. (Peas have seven chromosome pairs, but only two pairs are illustrated here.) The R and r alleles segregate at anaphase I, yielding two types of daughter cells for this locus. 1 Each gamete gets one long chromosome with either the R or r allele. 2 Fertilization recombines the R and r alleles at random. 3 Alleles at both loci segregate in anaphase I, yielding four types of daughter cells depending on the chromosome arrangement at metaphase I. Compare the arrangement of the R and r alleles in the cells on the left and right 1 Each gamete gets a long and a short chromosome in one of four allele combinations. 2 Fertilization results in the 9:3:3:1 phenotypic ratio in the F 2 generation. 3
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Figure 15.4 The F 2 generation showed a typical Mendelian 3:1 ratio of red eyes to white eyes. However, no females displayed the white-eye trait; they all had red eyes. Half the males had white eyes, and half had red eyes.
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This document was uploaded on 11/01/2011 for the course BIO 181 at BYU.

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Ch15 Diagrams - Chapter 15 Diagrams Practice Exam Questions P Generation Yellow-round Green-wrinkled Starting with two true-breeding pea plants

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