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I don’t understand the concept of Mendels formula. I don’t get how they used the ratios in table 3.4 to predict the number of genotypes in each generation and I was wondering if you could explain it better. I don’t know how they got those numbers.

I don’t understand the concept of Mendels formula. I don’t get how they used the ratios in table 3.4 to predict the number of genotypes in each generation and I was wondering if you could explain it better. I don’t know how they got those numbers.

Human Anatomy & Physiology (11th Edition)
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
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I don’t understand the concept of Mendels formula. I don’t get how they used the ratios in table 3.4 to predict the number of genotypes in each generation and I was wondering if you could explain it better. I don’t know how they got those numbers.
4:12 PM Thu Sep 9 * 63% Library Fundamentals of Biology I - CBEN110 - Beeler, Farnsworth, Shaffer - Fall. probability that allow you to predict the outcomes of genetic experiments. Tool for calculating probabilities Mendel used symbols and mathematics to represent a complex biological process that he did not understand at the molecular level. Based on your modern knowledge, you can understand the mechanism shown in Figure 3.7. On average, every time a heterozygote is self-pollinated, it produces 25% homozygous dominant peas, 50% heterozygous peas, and 25% homozygous recessive peas. A visual tool called a Punnett square in Figure 3.8 is helpful for calculating ratios of progeny based on gamete genotypes. For simplicity, it is easier to assume that each cross produces four peas, although four is just a number used for convenience. A Punnett square lists all of the possible gamete genotypes on the outside of the square (top and left), letting you simply combine all the columns and rows to produce the progeny genotypes inside the square. You can deduce phenotypes from the genotypes within each box. The ratio 1:2:1 for genotypes YY:Yy:yy was one of the famous ratios that Mendel published (Table 3.4). Using this ratio, Mendel projected n generations into the future, which was easy because he made a simplifying assumption that every plant produces exactly 4 peas and every generation maintains the exact 1:2:1 ratio. Mendel reasoned that if he started with a 1:2:1 ratio, the next generation will result in a ratio of 6:4:6, which simplifies to 3:2:3. Let's examine this logic and use Table 3.4 to predict the future. Red arrows connecting the first two generations show how each number was deduced. Look at the second generation data in Table 3.4. Each first generation homozygous pea will produce only homozygous pollen Yy × Yy maternal gamete genotypes genotypes second generation peas. Each Yy pea will produce one YY and one yy pea for a total of six YY peas and six yy peas in the second generation. Four heterozygotes will be present in the second generation, because each of the two heterozygous peas from the previous generation will produce two new heterozygotes; 2 x 2 = 4. Mendel repeated this pattern over and over and produced a formula to calculate the outcome for Y y Y YY Yy y Yy yy Figure 3.8 A Punnett square. Genotype and phenotype outcomes for mating two heterozygotes. Gamete genotypes are placed outside the colored boxes, and pea genotypes are placed inside the colored boxes. Phenotypes are represented by the yellow or green colored boxes. Original art. any generation, which is presented in the bottom row of the ratio columns. Generation #2 produced a YY ratio of 22 - 1 = 3, and the same formula describes the yy generations number of genotypes ratios ratio in the second generation. Note that the YY Yy yy YY Yy yy heterozygote component of the ratio is a constant, which helps explain why Mendel's contemporaries thought heterozygotes “are inclined to revert to the parental forms," reconfirming their mistaken understanding of inheritance patterns. Using Mendel's formula, you can easily predict the ratio of 2x1 YY 4 (2 x 2 Yy) х1 у. 1 4 YY 1 2 1 yy 3 9- 2 3 3 28 8 28 4 120 16 120 15 2 15 496 32 496 31 31 2n-1 2n -1 ... *** peas ten generations into the future without having to write down the outcomes of all the intermediate generations. Table 3.4 Ratio of pea genotypes for n future generations. Original art. Integrating Question 9. If you mated YY with yy peas, use Table 3.4 to predict the proportion of homozygous yellow, 3.1 How can traits disappear and reappear in a later generation? 91 of 583
Transcribed Image Text:4:12 PM Thu Sep 9 * 63% Library Fundamentals of Biology I - CBEN110 - Beeler, Farnsworth, Shaffer - Fall. probability that allow you to predict the outcomes of genetic experiments. Tool for calculating probabilities Mendel used symbols and mathematics to represent a complex biological process that he did not understand at the molecular level. Based on your modern knowledge, you can understand the mechanism shown in Figure 3.7. On average, every time a heterozygote is self-pollinated, it produces 25% homozygous dominant peas, 50% heterozygous peas, and 25% homozygous recessive peas. A visual tool called a Punnett square in Figure 3.8 is helpful for calculating ratios of progeny based on gamete genotypes. For simplicity, it is easier to assume that each cross produces four peas, although four is just a number used for convenience. A Punnett square lists all of the possible gamete genotypes on the outside of the square (top and left), letting you simply combine all the columns and rows to produce the progeny genotypes inside the square. You can deduce phenotypes from the genotypes within each box. The ratio 1:2:1 for genotypes YY:Yy:yy was one of the famous ratios that Mendel published (Table 3.4). Using this ratio, Mendel projected n generations into the future, which was easy because he made a simplifying assumption that every plant produces exactly 4 peas and every generation maintains the exact 1:2:1 ratio. Mendel reasoned that if he started with a 1:2:1 ratio, the next generation will result in a ratio of 6:4:6, which simplifies to 3:2:3. Let's examine this logic and use Table 3.4 to predict the future. Red arrows connecting the first two generations show how each number was deduced. Look at the second generation data in Table 3.4. Each first generation homozygous pea will produce only homozygous pollen Yy × Yy maternal gamete genotypes genotypes second generation peas. Each Yy pea will produce one YY and one yy pea for a total of six YY peas and six yy peas in the second generation. Four heterozygotes will be present in the second generation, because each of the two heterozygous peas from the previous generation will produce two new heterozygotes; 2 x 2 = 4. Mendel repeated this pattern over and over and produced a formula to calculate the outcome for Y y Y YY Yy y Yy yy Figure 3.8 A Punnett square. Genotype and phenotype outcomes for mating two heterozygotes. Gamete genotypes are placed outside the colored boxes, and pea genotypes are placed inside the colored boxes. Phenotypes are represented by the yellow or green colored boxes. Original art. any generation, which is presented in the bottom row of the ratio columns. Generation #2 produced a YY ratio of 22 - 1 = 3, and the same formula describes the yy generations number of genotypes ratios ratio in the second generation. Note that the YY Yy yy YY Yy yy heterozygote component of the ratio is a constant, which helps explain why Mendel's contemporaries thought heterozygotes “are inclined to revert to the parental forms," reconfirming their mistaken understanding of inheritance patterns. Using Mendel's formula, you can easily predict the ratio of 2x1 YY 4 (2 x 2 Yy) х1 у. 1 4 YY 1 2 1 yy 3 9- 2 3 3 28 8 28 4 120 16 120 15 2 15 496 32 496 31 31 2n-1 2n -1 ... *** peas ten generations into the future without having to write down the outcomes of all the intermediate generations. Table 3.4 Ratio of pea genotypes for n future generations. Original art. Integrating Question 9. If you mated YY with yy peas, use Table 3.4 to predict the proportion of homozygous yellow, 3.1 How can traits disappear and reappear in a later generation? 91 of 583
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Gregor Mendel is regarded as the father of genetics because of the work he did upon pea plants and gave the fundamental laws of inheritance that laid the groundwork of the genetics we know today. He studied various generations of the pea plant and observed how the characteristics and traits were being passed on from one generation to the other.

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