Genetics: Analysis and Principles
6th Edition
ISBN: 9781259616020
Author: Robert J. Brooker Professor Dr.
Publisher: McGraw-Hill Education
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Chapter 5, Problem 1QSDC
Recessive maternal effect genes are identified in flies (for example) when a
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As seen in the photo, Labradors come in three colors-- black, brown and yellow. What is the genetic basis for these different coat colors? One gene produces melanin, a pigment which is deposited in the dog's fur and makes the color dark. With this gene, allele B (black) is dominant to allele b. Only in the case of a recessive homozygote (bb) will the dog's phenotype be brown. The regulatory gene is separate from the melanin gene but it acts as a switch, either turning the melanin gene on or turning it off. Allele E is dominant and allows for the melanin to be deposited in the dog's fur ("on" switch), but if the switch gene is a recessive homozygote, the melanin is blocked ("off" switch) and a yellow dog is the result!
Review the information on Labrador retrievers above. What are the phenotypic ratios of the F1 generation offspring of two dihybrids? Make sure to match the numbers with coat colors (e.g, which number in the ration goes with which color). Use a Punnett square to…
As seen in the photo, Labradors come in three colors-- black, brown and yellow. What is the genetic basis for these different coat colors? One gene produces melanin, a pigment which is deposited in the dog's fur and makes the color dark. With this gene, allele B (black) is dominant to allele b. Only in the case of a recessive homozygote (bb) will the dog's phenotype be brown. The regulatory gene is separate from the melanin gene but it acts as a switch, either turning the melanin gene on or turning it off. Allele E is dominant and allows for the melanin to be deposited in the dog's fur ("on" switch), but if the switch gene is a recessive homozygote, the melanin is blocked ("off" switch) and a yellow dog is the result!
1. Two other Labradors mate and produce puppies. Their genotypes are Bbee and BbEe. What color are each parent and what are the phenotypic rations of their offspring in the F1 Generation? Show your work with a Punnett square.
You are working in the lab with strains of Drosophila that have either normal legs or abnormally short legs and you are studying the gene responsible. You know that normal legs are dominant to short legs. You come across a misplaced fly with normal legs, but you are not sure of his genetic background and you want to keep him in your experiments.
(Without doing a molecular analysis), How could you figure out whether he was heterozygous or homozygous for the leg gene that you are studying? (Describe what you would do and how the results would answer the question.)
What is the procedure you described above called?
Chapter 5 Solutions
Genetics: Analysis and Principles
Ch. 5.1 - A female snail that coils to the left has...Ch. 5.1 - 2. What is the molecular explanation for maternal...Ch. 5.2 - 1. In fruit flies, dosage compensation is achieved...Ch. 5.2 - 2. According to the Lyon hypothesis,
a. one of...Ch. 5.2 - Prob. 3COMQCh. 5.3 - 1. In mice, the copy of the Igf2 gene that is...Ch. 5.3 - 2. A female mouse that is is crossed to a male...Ch. 5.3 - Prob. 3COMQCh. 5.3 - Prob. 4COMQCh. 5.4 - 1. Extranuclear inheritance occurs due to
a....
Ch. 5.4 - 2. A cross is made between a green four-o’clock...Ch. 5.4 - 3. Some human diseases are caused by mutations in...Ch. 5.4 - 4. Chloroplasts and mitochondria evolved from an...Ch. 5 - Define the term epigenetic inheritance, and...Ch. 5 - 2. Describe the inheritance pattern of maternal...Ch. 5 - A maternal effect gene exists in a dominant N...Ch. 5 - 4. A Drosophila embryo dies during early...Ch. 5 - 5. For Mendelian inheritance, the nuclear genotype...Ch. 5 - Suppose a maternal effect gene exists as a...Ch. 5 - Suppose that a gene affects the anterior...Ch. 5 - Explain why maternal effect genes exert their...Ch. 5 - As described in Chapter 22, researchers have been...Ch. 5 - 10. With regard to the numbers of sex chromosomes,...Ch. 5 - 11. What is a Barr body? How is its structure...Ch. 5 - Among different species, describe three distinct...Ch. 5 - 13. Describe when X-chromosome inactivation occurs...Ch. 5 - 14. Describe the molecular process of X-chromosome...Ch. 5 - Prob. 15CONQCh. 5 - 16. How many Barr bodies would you expect to find...Ch. 5 - 17. Certain forms of human color blindness are...Ch. 5 - A black female cat (XBXB) and an orange male cat...Ch. 5 - Prob. 19CONQCh. 5 - When does the erasure and reestablishment phase of...Ch. 5 - In what types of cells would you expect de novo...Ch. 5 - 22. On rare occasions, people are born with a...Ch. 5 - Genes that cause Prader-Willi syndrome and...Ch. 5 - Prob. 24CONQCh. 5 - What is extranuclear inheritance? Describe three...Ch. 5 - Prob. 26CONQCh. 5 - Among different species, does extranuclear...Ch. 5 - Extranuclear inheritance often correlates with...Ch. 5 - Prob. 29CONQCh. 5 - Prob. 30CONQCh. 5 - Which of the following traits or diseases is (are)...Ch. 5 - Prob. 32CONQCh. 5 - 33. Describe how a biparental pattern of...Ch. 5 - Figure 5.1 describes an example of a maternal...Ch. 5 - 2. Discuss the types of experimental observations...Ch. 5 - Prob. 3EQCh. 5 - As a hypothetical example, a trait in mice results...Ch. 5 - You have a female snail that coils to the right,...Ch. 5 - Prob. 6EQCh. 5 - 7. Figure 5.6 describes the results of...Ch. 5 - Prob. 8EQCh. 5 - In the experiment of Figure 5.6, why does a clone...Ch. 5 - Prob. 10EQCh. 5 - 11. A variegated trait in plants is analyzed using...Ch. 5 - 1. Recessive maternal effect genes are identified...Ch. 5 - Prob. 2QSDC
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- Hemophilia and color blindness are both recessive conditions caused by genes on the X chromosome. To calculate the recombination frequency between the two genes, you draw a large number of pedigrees that include grandfathers with both hemophilia and color blindness, their daughters (who presumably have one chromosome with two normal alleles and one chromosome with two mutant alleles), and the daughters sons. Analyzing all the pedigrees together shows that 25 grandsons have both color blindness and hemophilia, 24 have neither of the traits, 1 has color blindness only, and 1 has hemophilia only. How many centimorgans (map units) separate the hemophilia locus from the locus for color blindness?arrow_forwardThe young woman shown at right has albinismvery pale skin, white hair, and pale blue eyes. This phenotype is due to the absence of melanin, which imparts color to the skin, hair, and eyes. It typically is caused by a recessive allele. In the following situations, what are the probable genotypes of the father, the mother, and their children? a. Both parents have normal phenotypes; some of their children are albino and others are not. b. Both parents and all their children are albino. c. The mother is not albino, the father is albino, and one of their four children is albino.arrow_forwardA recessive maternal effect mutant in zebrafish, called ichabod, results in embryos lacking heads that are non-viable. You have been instructed to identify females that are homozygous for the ichabod mutant allele. At your disposal are a tank of wild-type fish (males and females), a tank of male and female parental fish that are all heterozygous for the ichabod mutant allele (ichabod/+), and a tank of F1 fish derived from a cross between a heterozygous male and heterozygous female (ichabod/+). Which of the following would be a way to identify females that are homozygous mutant, i.e. ichabod/ichabod? Select all answers that would work.arrow_forward
- Eye colors are passed down through generations, but sometimes genetic variations can lead to surprising results in eye colors (dark eye color, still rocks!?) Some examples are found below. Is there truth behind the following? Provide explanations for your answer. Two parents with blue eyes cannot have a brown-eyed child and vice-versa. Eyes with more than one color stems from parents with two different eye colors. People with violet eyes are mutants. People with red or pinkish eye color can have dark-eyed parents.arrow_forwardWhen two mutant flies having white eyes were crossed, all of the offspring showed wild type red eyes. How is this possible? The parents carried mutations on different but complementary genes whose products are both required for the red eye phenotype. The parents carried different mutations on the same gene whose product is required for the red eye phenotype. The parents carry recessive lethal mutations that affect the survival of the white-eyed flies among the offspring. The red eye phenotype is recessive to the white eye phenotype, which is why the red eye only appears in the F1 generation. The white eye allele shows dominant epistasis over the red eye allele.arrow_forwardIn a particular country in sub-Saharan Africa, a medical study revealed that 0.075% of the country's population are suffering from sickle-cell anemia. Sickle cell disease is caused by a mutation in the haemoglobin-Beta gene found on chromosome 11. Sickle cell anemia is controlled by a pair of alleles, H and h, where the individuals with the illness have the homozygous recessive genotype; those with normal red blood cells have the alternative genotype. Using the Hardy-Weinberg's equation, calculate the percentage of the population of the two genotypes for normal blood cells. In a few remote areas in that country, the percentage of sickle cell anemia reaches as high as 5%. Calculate the percentage of homozygous and heterozygous individuals with the normal blood cells and find the ratio for both phenotypes.arrow_forward
- Our understanding of maternal effect genes has been greatly aided by their identification in experimental organisms such as Drosophila melanogaster and Caenorhabditis elegans. In experimental organisms with a short generation time, geneticists have successfully searched for mutant alleles that prevent the normal process of embryonic development. In many cases, the offspring die at early embryonic or larval stages. These are called maternal effect lethal alleles. How would a researcher identify a mutation that produced a recessive maternal effect lethal allele?arrow_forwardTwo different strains of Drosophila, strain A and strain B, each has a recessive mutation that results in abnormally bright red eye color. (Wild type flies have brownish red eye color). When a homozygous strain A fly is crossed with a homozygous B fly, all of the progeny have the dominant wild type eye color. The wild type-eyed progeny were allowed to breed among themselves to produce the F2 generation. The F2 generation consisted of 92 wild type and 74 bright red-eyed flies. Write the genotype(s) of the flies in each generation. Use a low dash (e.g. A_ B_) to indicate genotypes that could be either homozygous or heterozygous) a) parental strain A b) parental strain B c) wild type progeny (F1) d) wild type F2 e) bright-eyed F2arrow_forwardYou have been tasked by a pharmaceutical company to generate a novel strain of Cannabis sativa for therapeutic purposes. Consider a Cannabis strain with three genes (called gene 1, gene 2 and gene 3) that are on different chromosomes and assort independently. Each gene has two alleles, described below: The T allele for gene 1 is dominant and associated with the trait of producing large amounts of terpenes, and the t allele is recessive and associated with the trait of producing a low amount of terpenes The S allele for gene 2 is dominant and associated with the trait of fast growth, and the s allele is associated with the trait of slow growth The F allele for gene 3 is associated with the trait of producing large flowers, and the f allele is associated with the trait of producing small flowers Assume that an individual plant that is heterozygous for genes 1 and 2, but homozygous ff for gene 3 self-fertilizes. What is the probability of getting a plant that produces a large number of…arrow_forward
- The pedigree below shows the inheritance of the rare blistering disease (epidermolysis) in dogs. Affected individuals are indicated in black, and those not showing symptoms (phenotypically normal) of the disease in white. The pedigree below represents an autosomal recessive disease. What characteristic(s) of the pedigree supports this statement? Number the generations and individuals in this pedigree. Write the genotypes and their genotype probabilities for all the individuals in the pedigree. Use E/eas the allele symbols.arrow_forwardIn humans, the genetic disease cystic fibrosis is caused by a recessive allele (a). The normal (healthy) allele is dominant (A). What is the genotype of someone who has cystic fibrosis? What are the two different genotypes that a healthy person could have? If two people were both heterozygous for the cystic fibrosis gene, what fraction of their children would be likely to have this disease? Hint: Draw a Punnett square to figure it out.arrow_forward. Which of the following inheritance patterns was observed, in the experiments of Alfred Hershey and Martha Chase, using the T2 bacteriophage of Escherichia coli? radioactive proteins were passed on to viral progeny, but not radioactive polynucleotides radioactive polynucleotides were passed on to viral progeny, but not radioactive proteins both radioactive proteins and radioactive polynucleotides were passed on to viral progeny both radioactive polynucleotides and radioactive proteins were passed on to viral progeny neither radioactive proteins nor radioactive polynucleotides were passed on to viral progeny The Hershey / Chase experiments (above) demonstrated that the T2 bacteriophage uses: phosphate-containing molecules for its genetic material, but not sulfur-containing molecules sulfur-containing molecules for its genetic material, but not phosphate-containing molecules both phosphate-containing and sulfur-containing molecules for its genetic material both sulfur-containing…arrow_forward
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