Concept explainers
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The PKU is present in the person those are homozygous recessive for this disease allele. The reasons for this disease allele can be present in various frequencies in those populations that can lead to mental retardation in homozygous person.
Introduction:
Genetic drift (allelic drift) can be defined as the variation in the frequency of an existing allele in a population due to an accidental sampling of organisms. Allele frequency of a population is the fraction of the copies of one gene which share a specific form. Reproductive isolation can be defined as the barrier created by the environment, such as a mountain range or river that does not allow mating between two groups of same species.
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Biology: Science for Life with Physiology (6th Edition) (Belk, Border & Maier, The Biology: Science for Life Series, 5th Edition)
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- In Sweden 1/500 are born with an autosomal recessive disorder called thalassemia. What is the carrier frequency within the population?arrow_forwardPhenylketonuria (PKU) is an autosomal recessive disease in which individuals with PKU cannot metabolize phenylalanine. A diet rich in phenylalanine can result in severe mental retardation if not caught early and the ingestion of the amino acid avoided. The occurrence of new alleles causing PKU in a Korean population that has PKU is 4 out of 33 and the frequency of the disease is 1 in 10,000 in the general population (Lee et al. 2008). What is the mutation rate of PKU in this population? a. 0.12 b. 7.25 x 10-7 c. 0.01 d. 6.8 x 10-4arrow_forwardIn the genetics unit you learned that sickle cell anemia is an autosomal recessive condition. In 2016, assume in the City of Markham there are 1000 people out of 300000 people who have sickle cell anemia. Assume global warming continues for the next 50 years and in the year 2066 there are 20000 people out of 500000 in Markham who have sickle cell anemia. a)What are the allele frequencies in 2016? What are the allele frequencies in 2066? Is microevolution evident? b)Due to global warming, assume the numbers of malaria carrying mosquitoes in Markham dramatically increased between 2016 and 2066. What do you believe is the main cause of the microevolution in Markham? (Hint- refer to the 5 factors affecting microevolution and refer back…arrow_forward
- In Huntington’s disease, the wild-type allele, h, is recessive to the disease allele, H. The persistence of an autosomal dominant allele that is fatal in 100% of cases is best explained by which of the following? A) The dominant allele only has moderate negative effects during adolescence and young adulthood. B) The wild-type h allele continues to spontaneously mutate into the dominant H allele. C) The persistence of any given allele in nature is determined almost wholly by chance. D) The disease has no effects until the individual has reached an age far past the normal age for reproduction.arrow_forwardPlease read the scenario below, and then answer the question (in bold) that follows. Tay-Sachs disease is a fatal autosomal recessive disorder in children (usually by age 5) that causes a progressive degeneration of the central nervous system. This disease affects 1 in 3,500 newborns of European Ashkenazi Jewish ancestry in the U.S. population. What is the number of carriers in the population? a. 1 person b. 60 persons c. 116 persons d. 3,383 persons e. 3,441 personsarrow_forwardIn genetics, the dash symbol (–) is a “wild card” that stands for either the dominant allele or the recessive allele; for example, A– means the individual has either the genotype AA or Aa. Two genes that undergo independent assortment affect coat color in Duroc pigs. Each gene has two alleles, one of which is dominant for coat color. Genotypes of the form A– B– are red, those of the form A– bb and aa B– are sandy, and genotype aa bb is white. What ratio of red:sandy:white is expected from the cross Aa Bb x Aa Bb?arrow_forward
- Identify each of the following as an example of allele, genotype, and/or phenotype frequency: A. Approximately 1 in 2500 people of Northern European descent is born with cystic fibrosis. B. The percentage of carriers of the sickle cell allele in West Africa is approximately 13%. C. The number of new mutations for achondroplasia, a genetic disorder, is approximately 5 × 10–5.arrow_forwardPhenylketonuria (PKU) is an inherited disease caused by a recessive allele. Individuals with PKU have two recessive alleles and have very low levels of an enzyme that is needed to properly break down proteins. If a woman and her husband are both carriers and have three children, what is the probability of each of the following? Show your math. (Hint: You can represent your probabilities as fractions or decimals, but probabilities are always between 0 and 1) a. All three children are of normal phenotype. b. One or more of the three children have the disease. c.All three children have the disease.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_forward
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