Concept explainers
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?
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Chapter 15 Solutions
Human Heredity: Principles and Issues (MindTap Course List)
- In 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_forwardIn a population of martians the hair color (H= purple or h=green) and eye-color (E=red or e=yellow) are very close together on the same chromosome. One heterozygote male, who knows that his dad was homozygous dominant and his mom had green hair and yellow eyes is considering fertilizing a homozygous recessive female. How many green-haired yellow-eyed offspring (out of 16) would they expect to have?arrow_forwardIn flies, small wings are recessive to normal wings. If a cross between two flies produces 8 small-wing offspring and 28 normal-wing offspring, what are the most likely genotypes of the parents? (Use SS to represent the normal-wing allele and ss to represent the short-wing allele.)arrow_forward
- The pedigree below shows three generations of a family that carries albinism, an autosomal recessive genetic disease. In the third generation, a child was born with albinism but the genotypes of the rest of the family are unknown. No other family members have the disease. Assume normal, Mendelian genetics with no new mutations. What are the genotypes of the parents of the affected child? A) There is not enough information to determine their genotypes B) Both are homozygous for albinism C) One is hemizygous and one is heterozygous for albinism D) Both are heterozygous for albinism E) One is homozygous and one is heterozygous for abinismarrow_forwardIn humans, the genes for coloblindedness and hemophilia re both located on the X chromosome with no corresponding gene in the Y. These are both recessive alleles. a. If a man and a woman, both with normal vision, marry and have a colorblind son, draw the Punnet square that illustrates this. b. If the man dies and the woman remarries to a colorblind man, draw a Punnet Square showing the type of children could be expected from hre second marriage. How many/what percentages of each could ne expectedarrow_forwardIn humans, the genes for colorblindness and hemophilia are both located on the X chromosome with no corresponding gene in the Y. These are both recessive alleles. If a man and a woman, both with normal vision, marry and have a colorblind son, draw the Punnet square that illustrates this. If the man dies and the woman remarries a colorblind man, draw a Punnet Square showing the type of children that could be expected from the second marriage. How many/what percentages of each could be expected.arrow_forward
- In a breed of cattle, rough coat is dominant over smooth coat and black coat is codominant to red. Is the loci of the two pairs of gene concerned on the same chromosome?arrow_forwardYou are a gene hunter, trying to find the genetic basis for a rare inherited disease. Examination of six pedigrees of families affected by the disease provides inconsistent results. For two of the families, the disease is co-inherited with markers on chromosome 7. For the other four families, the disease is co-inherited with markers on chromosome 12. Explain how this difference might have arisen.arrow_forwardMy friend Pierre is red-green color blind and so is his father, but his mother is not color-blind. In the diagram below: a) Indicate the sex chromosomes of each member of Pierre's family b) Indicate the color-blindness allele associated with each chromosome of Pierre and his family (let B represent the color vision allele and let b represent a color blindness allele. If an allele cannot be determined with certainty, label the chromosome with a question mark c) Finally, determine the probability that Pierre's sister is color blind. Explain your reasoning.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 the case of carnation flower, what do you think a flower carnation would look like if the red and white phenotypes were codominant instead?arrow_forwardUsing the pedigree chart attached: Above is a pedigree for colorblindness. Based on the pedigree, is the disease dominant or recessive and is it sex-linked or autosomal? Why? Furthermore, what is the probability that 18 on this chart is affected but the condition, and what is the probability that 18 is a carrier? Why? Are the probability of being a carrier and an affected individual different? Why?arrow_forward
- Human Heredity: Principles and Issues (MindTap Co...BiologyISBN:9781305251052Author:Michael CummingsPublisher:Cengage Learning