Genetics: From Genes to Genomes
6th Edition
ISBN: 9781259700903
Author: Leland Hartwell Dr., Michael L. Goldberg Professor Dr., Janice Fischer, Leroy Hood Dr.
Publisher: McGraw-Hill Education
expand_more
expand_more
format_list_bulleted
Concept explainers
Textbook Question
Chapter 2, Problem 34P
The gene that likely controlled flower color (purple or white) in Mendel’s pea plants has also been identified. The flower color gene specifies a protein called bHLH required by cells to make three different enzymes (DFR, ANS, and 3GT) that function in the pathway shown in the accompanying figure, leading to synthesis of the purple pigment anthocyanin.
a. | What is the most likely explanation for the difference between the dominant allele (P) and the recessive allele (p) of the gene responsible for these flower colors? |
b. | Given the biochemical pathway shown, could a different gene have been the one governing Mendel’s flower colors? |
Expert Solution & Answer
Want to see the full answer?
Check out a sample textbook solutionStudents have asked these similar questions
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.
a.Draw a hypothetical biochemical pathway to explain the production of purple and white flowers in sweet peas.
Multiple crosses were made between true-breeding lines of black and yellow Labrador retrievers. All the F1 progeny were yellow. When these progeny were intercrossed, they produced an F2 consisting of 121 yellow, 9 black and 30 chocolate.
What epistatic ratio and what kind of epistasis is approximated in the F2?
Propose a biochemical pathway for coat color in Labrador retrievers based on the type of epistasis.
Correlate each genotype with the phenotype that would occur in your pathway. Also show the frequency of each genotype.
A-B-
A-bb aaB- aabb
Leber Congenital Amaurosis (LCA) causes progressive vision loss due to defects in the gene that encodes RPE65 isomerase. Affected individuals are homozygous recessive for mutant alleles of the RPE65 gene. You are trying to determine the molecular nature of the mutations in three individuals with LCA. For ease of analysis, you may assume that each individual is homozygous for the same mutant allele (though the three individuals have different mutations than each other). You use the polymerase chain reaction to amplify DNA from each patient and you determine the sequence of the DNA and compare it to unaffected individuals. You identify the following differences. Note that the non-template strand of DNA is given and the changes are highlighted using red boldface. You can assume that the sequences are in the first reading frame (eg. the first three nucleotides of each sequence is a codon). The coding region of the gene is 1602 bp and the position of the sequences shown below is…
Chapter 2 Solutions
Genetics: From Genes to Genomes
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 - Some inbred strains of the weedy plant Arabidopsis...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 - In a standard deck of playing cards, four suits...Ch. 2 - How many genetically different eggs could be...Ch. 2 - What is the probability of producing a child that...Ch. 2 - A mouse sperm of genotype a B C D E fertilizes an...Ch. 2 - Your friend is pregnant with triplets. She thinks...Ch. 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 - The achoo syndrome sneezing in response to bright...Ch. 2 - A pea plant from a pure-breeding strain that is...Ch. 2 - The following table shows the results of different...Ch. 2 - A pea plant heterozygous for plant height, pod...Ch. 2 - In the fruit fly Drosophila melanogaster, the...Ch. 2 - Based on the information you discovered in the...Ch. 2 - Considering the yellow and green pea color...Ch. 2 - What would have been the outcome the genotypic and...Ch. 2 - Recall that Mendel obtained pure-breeding with...Ch. 2 - The gene that likely controlled flower color...Ch. 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 - Consider the cystic fibrosis pedigree in Figure...Ch. 2 - Prob. 42PCh. 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...Ch. 2 - The following pedigree shows the inheritance of...
Knowledge Booster
Learn more about
Need a deep-dive on the concept behind this application? Look no further. Learn more about this topic, biology and related others by exploring similar questions and additional content below.Similar questions
- A geneticist examines an ear of corn in which most kernels are yellow, but he finds a few kernels with purple spots, as shown here. Give a possible explanation for the appearance of the purple spots in these otherwise yellow kernels, accounting for the different sizes of the spots.arrow_forwardThe HbβS(sickle-cell) allele of the human β-globingene changes the sixth amino acid in the β-globinchain from glutamic acid to valine. In HbβC, the sixthamino acid in β-globin is changed from glutamic acidto lysine. What would be the order of these two mutations within the map of the β-globin gene?arrow_forwardThe following genotypes of two independently assorting autosomal genes determine coat color in rats:A-B- (gray); A-bb (yellow); aaB-(black); aabb (cream)A third gene pair on a separate autosome determines whetherany color will be produced. The CC and Cc genotypes allow coloraccording to the expression of the A and B alleles. However,the cc genotype results in albino rats regardless of the A and Balleles present. Determine the F1 phenotypic ratio of the followingcrosses: (a)AAbbCC * aaBBcc; (b) AaBBcc * AABbcc;(c) AaBbCc * AaBbcc.arrow_forward
- A complex biochemical pathway is shown below, along with the alleles that either promote or inhibit each step of the pathway leading to a phenotype. Gene A has alleles A and a, B has alleles B and b, and so forth. Genes B and C are duplicate dominant epistatic lethal as heterozygotes (i.e. Bb Cc are lethal). Genes D and E are duplicate dominant epistatic (i.e. dd eg = desired phenotype). If I were to cross AA Bb cc Dd Ee with aa BB Cc Dd e, (i) (ii) What proportion of all offspring don't show the phenotype? What proportion of offspring survive? Gene A Gene B B Gene D a Gene C Gene Earrow_forwardGenes A, B, C, D, and E are independently assorting. The dominant alleles A, B, C and D encode enzymes that catalyse the corresponding reactions indicated above. The recessive alleles a, b, c and d are non-functional and do not produce active enzymes. The dominant E allele totally inhibits the action of gene C, while the recessive allele e has no effect. a) Determine the F1 and F2 phenotypes from a cross between AAbbCCDDEE and AABBCCDDee plants. b) What proportion of the offspring of an AaBBCCDdEe x AaBBCcDdEe cross is expected to have coloured flowers?arrow_forwardSpherocytosis is an inherited blood disease in which erythrocytes (red blood cells) are spherical instead of biconcave. This condition is inherited in a dominant fashion, with ANK1 (the nonfunctional mutant allele) dominant to ANK1+. In people with spherocytosis, the spleen recognizes the spherical red blood cells as defective and removes them from the bloodstream, leading to anemia; this removal occurs with different efficiency in different people. Some people with spherical erythrocytes suffer severe anemia, some have mild anemia, and others do not have any symptoms of anemia. When 2400 people with the genotype ANK1/ANK1+ were examined, it was found that all of them had spherical erythrocytes, 2250 had anemia of varying severity, and 150 had no anemia symptoms. The ANK1/ANK1 genotype is never observed. Which evidence suggests that spherocytosis is incompletely penetrant?arrow_forward
- The flower color of genetically identical hemp plants (clones) is purple when the flowers develop under cold environment (<14 °C) and white when they develop under hot environment (>30 °C). Describe in detail a molecular mechanism that could explain how these two groups of genetically identical plants differ in their gene expressions to produce different flower colors?arrow_forwardIn McCune-Albright syndrome, fibrous connective tissue replaces bone, tan patches (café-au-lait spots) dot the skin, and hormone abnormalities cause early puberty and malfunction of the thyroid, pituitary, and adrenal glands. The phenotype is highly variable, and all patients are somatic mosaics for the mutation, which is in the gene GNAS1. Why is the condition seen only in mosaics?arrow_forwardConsidering Figure 2-13, if you had a homozygous double mutant m3/m3 m5/m5, would you expect it to be mutant in phenotype? (Note: This line would have two mutant sites in the same coding sequence.)arrow_forward
- Consider two maize plants:a. Genotype C/c m ; Ac/Ac+, where cm is an unstable allele caused by a Ds insertionb. Genotype C/c m, where cm is an unstable allele caused by Ac insertionWhat phenotypes would be produced and in what proportions when (1) each plant is crossed with a basepair-substitution mutant c/c and (2) the plant in part a is crossed with the plant in part b? Assume that Ac and c are unlinked, that the chromosome-breakage frequency is negligible, and that mutant c /C is Ac+.arrow_forwardThe gene controlling ABO blood type and the gene underlying nail-patella syndrome are said to show linkage. What does that mean in terms of their relative locations in the genome? What does it mean in terms of how the two traits are inherited with respect to each other?arrow_forwarda. If an individual who is homozygous for the mutation found in individual 2 and heterozygous for the mutation found in individual 4 marries an individual who is homozygous for the mutation found in individual 4 and heterozygous for the mutation found in individual 2, what will be the phenotype of their children? b. List the intermediate that would build up in each of the types of children who could not produce protein E.arrow_forward
arrow_back_ios
SEE MORE QUESTIONS
arrow_forward_ios
Recommended textbooks for you
- Human Heredity: Principles and Issues (MindTap Co...BiologyISBN:9781305251052Author:Michael CummingsPublisher:Cengage Learning
Human Heredity: Principles and Issues (MindTap Co...
Biology
ISBN:9781305251052
Author:Michael Cummings
Publisher:Cengage Learning
Mitochondrial mutations; Author: Useful Genetics;https://www.youtube.com/watch?v=GvgXe-3RJeU;License: CC-BY