Concept explainers
To determine: The inheritance pattern of the mutation creating a null allele.
Introduction: The mutation is the change in the
To determine: The assumptions needed to answer the inheritance of the mutant allele.
Introduction: The genes are the sequence of nucleotides that are present on the chromosomes and encode for a specific protein that plays a crucial role in the functioning of the different processes in an organism. The gene is located at specific gene loci and can be structural or regulatory in nature.
Want to see the full answer?
Check out a sample textbook solutionChapter 2 Solutions
Introduction to Genetic Analysis
- In a college genetics laboratory course, a healthy student constructs a karyotype from a cell from inside her cheek. She finds only one chromosome 3 and one chromosome 21, plus two unusual chromosomes that do not seem to have matching partners. a. What type of chromosomal abnormality does she have? b. Why doesn’t she have any symptoms? c. Would you expect any of her relatives to have particular medical problems?arrow_forwardSix months pregnant, an expectant mother had a routine ultrasound that showed that the limbs of the fetus were unusually short. Her physician suspected that the baby might have a genetic form of dwarfism called achondroplasia, an autosomal dominant trait occurring with a frequency of about 1 in 27,000 births. The parents were directed to a genetic counselor to discuss this diagnosis. In the conference, they learned that achondroplasia is caused by a mutant allele. Sometimes it is passed from one generation to another, but in 80 percent of all cases it is the result of a spontaneous mutation that arises in a gamete of one of the parents. They also learned that most children with achondroplasia have normal intelligence and a normal life span. 1. What information would be most relevant to concluding which of the two mutation origins, inherited or new, most likely pertains in this case? How does this conclusion impact on this couple’s decision to have more children? 2. It has been…arrow_forwarda geneticist has obtained 2 true-breeding strains of mice, each homozygous for an independently discovered recessive mutation that prevents the formationof hair on the body. one mutant strain is called naked, and the other is hairless. to determine whether the 2 mutations are alleles, the geneticist crosses naked and hairless mice with each other. All the offspring lack hair on their bodies. A: are naked and hairless mutations 2 different alleles? yes or no B: what type of experiment is this calledarrow_forward
- Colorblindness and hemophilia are both X-linked traits in humans. Explain how a female who has a defective color vision gene on one X chromosome and a defective blood clotting gene causing hemophilia on the other X chromosome can be neither a hemophiliac nor colorblind? Please discuss the effect of Gene dosage compensation in your answer and in your answer describe the molecular process by which this occurs.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_forwardLet's consider a paternally imprinted gene. A female skink inherited alleles that that confer: 1) a mutant violet tail-color in the egg and 2) a mutant violet tail-color allele in the sperm. A male skink mate inherited a wild-type blue allele from the sperm and a mutant violet allele from the egg. They have 500 offspring. a. What tail color phenotypes do the parent male and parent female skinks have? Briefly explain your reasoning. female = male = b. What fraction of the offspring do you expect to have each phenotype (blue and violet tail color)? Briefly explain your reasoning/show your work.arrow_forward
- For a particular gene, homozygous dominant AA and heterozygous Aa individuals produce green pigment, while homozygous recessive aa individuals produce yellow pigment. During the course of your research you discover the a1 allele that contains a class IlI transposon insertion. Allele A is dominant to a1. Which genotype is capable of producing a mixture of green and yellow pigment?arrow_forwardFour human pedigrees are shown in the accompanying illustration. The black symbols represent an abnormal phenotype inherited in a simple Mendelian manner.a. For each pedigree, state whether the abnormal condition is dominant or recessive. Try to state the logic behind your answer. b. For each pedigree, describe the genotypes of as many persons as possible.arrow_forwardFamilial retinoblastoma, a rare autosomal dominant defect, arose in a large family that had no prior history of the disease. Consider the following pedigree (the darkly colored symbols represent affected individuals): a. Circle the individual(s) in which the mutation most likely occurred. b. Is the person who is the source of the mutation affected by retinoblastoma? Justify your answer. c. Assuming that the mutant allele is fully penetrant, what is the chance that an affected individual will have an affected child?arrow_forward
- Susan’s grandfather was deaf, and passed down a hereditary form of deafness within Susan’s family as shown in Figure Q19–12.A. Is this mutation most likely to be dominant or recessive?B. Is it carried on an autosome or a sex chromosome? Why?C. A complete SNP analysis has been done for all of the 11 grandchildren (4 affected, and 7 unaffected). In comparing these 11 SNP results, how long a haplotype block would you expect to find around the critical gene? How might you detect it?arrow_forwardThe wild-type (normal) fruit fly, Drosophila melanogaster, has straight wings and long bristles. Mutant strains have been isolated that have either curled wings or short bristles. The genes representing these two mutant traits are located on separate chromosomes. Carefully examine the data from the following five crosses shown below (running across both columns). (a) Identify each mutation as either dominant or recessive. In each case, indicate which crosses support your answer. (b) Assign gene symbols and, for each cross, determine the genotypes of the parents.arrow_forwardRegarding Mendelian inheritance in diploid individuals, (Read each statement carefully. Select all of the statements below that are true (that you agree with). Leave any statements that are false (that you do not agree with) un- selected.) a diploid individual receives two copies of every autosome from the previous generation. for every autosomal gene inherited by an individual, both copies can come from one parent. a diploid individual gives two copies of every autosome to a child in the next generation. to be diploid means that two independent genes are specified in the individual's genotype.arrow_forward
- Human Heredity: Principles and Issues (MindTap Co...BiologyISBN:9781305251052Author:Michael CummingsPublisher:Cengage Learning