Genetics: From Genes to Genomes, 5th edition
5th Edition
ISBN: 9780073525310
Author: Leland H. Hartwell, Michael L. Goldberg, Janice A. Fischer, Leroy Hood, Charles F. Aquadro
Publisher: McGraw-Hill Education
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Textbook Question
Chapter 2, Problem 29P
Considering the yellow and green pea color
a. | What is the biochemical function of the protein that is specified by the gene responsible for the pea color phenotype? |
b. | A null allele of a gene is an allele that does not specify any of the biochemical function that the gene normally provides. Of the two alleles Y and y, which is more likely to be a null allele? |
c. | In terms of the underlying biochemistry, why is the Y allele dominant to the y allele? |
d. | Why are peas that are yy homozygotes green? |
e. | The amount of the protein specified by a gene is roughly proportional to the number of functional copies of the gene carried by a cell or individual. What do the phenotypes of YY homozygotes, Yy heterozygotes, and yy homozygotes tell us about the amount of the Sgr enzyme (the product of the pea color gene) needed to produce a yellow color? |
f. | The Sgr enzyme is not needed for the survival of a pea plant, but the genomes of organisms contain many so-called essential genes needed for an individual’s survival. For such genes, heterozygotes for the normal allele and the null allele survive, but individuals homozygous for the null allele die soon after the male and female gametes, each with a null allele, come together at fertilization. In light of your answer to part (e), what does this fact tell you about the advantage to an organism of having two copies of their genes? |
g. | Do you think that a single pea pod could contain peas with different phenotypes? Explain. |
h. | Do you think that a pea pod could be of one color (say, green) while the peas within the pod could be of a different color (say, yellow)? Explain. |
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Some sweet-pea plants have purple flowers and others have white flowers. A homozygous variety of sweet pea that has purple flowers is crossed with a homozygous variety that has white flowers. All the F1have purple flowers. When these F1 self-fertilize, the F2 appear in a ratio of 916 purple to 716 white.
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Chapter 2 Solutions
Genetics: From Genes to Genomes, 5th edition
Ch. 2 - For each of the terms in the left column, choose...Ch. 2 - During the millennia in which selective breeding...Ch. 2 - Describe the characteristics of the garden pea...Ch. 2 - An albino corn snake is crossed with a...Ch. 2 - Two short-haired cats mate and produce six...Ch. 2 - Piebald spotting is a condition found in humans in...Ch. 2 - As a Drosophila research geneticist, you keep...Ch. 2 - A mutant cucumber plant has flowers that fail to...Ch. 2 - In a particular population of mice, certain...Ch. 2 - In humans, a dimple in the chin is a dominant...
Ch. 2 - Among Native Americans, two types of earwax...Ch. 2 - Imagine you have just purchased a black stallion...Ch. 2 - If you roll a die singular of dice, what is the...Ch. 2 - Prob. 14PCh. 2 - How many genetically different eggs could be...Ch. 2 - What is the probability of producing a child that...Ch. 2 - Prob. 17PCh. 2 - Galactosemia is a recessive human disease that is...Ch. 2 - Albinism is a condition in which pigmentation is...Ch. 2 - A cross between two pea plants, both of which grew...Ch. 2 - A third-grader decided to breed guinea pigs for...Ch. 2 - The self-fertilization of an pea plant produced...Ch. 2 - Prob. 23PCh. 2 - A pea plant from a pure-breeding strain that is...Ch. 2 - Prob. 25PCh. 2 - A pea plant heterozygous for plant height, pod...Ch. 2 - In the fruit fly Drosophila melanogaster, the...Ch. 2 - Prob. 28PCh. 2 - Considering the yellow and green pea color...Ch. 2 - Prob. 30PCh. 2 - Prob. 31PCh. 2 - Prob. 32PCh. 2 - For each of the following human pedigrees,...Ch. 2 - Consider the pedigree that follows for cutis laxa,...Ch. 2 - A young couple went to see a genetic counselor...Ch. 2 - Huntington disease is a rare fatal, degenerative...Ch. 2 - Is the disease shown in the following pedigree...Ch. 2 - Figure 2.22 shows the inheritance of Huntington...Ch. 2 - Prob. 39PCh. 2 - People with nail-patella syndrome have poorly...Ch. 2 - Midphalangeal hair hair on top of the middle...Ch. 2 - A man with Huntington disease he is heterozygous...Ch. 2 - Explain why disease alleles for cystic fibrosis CF...
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