Concept explainers
Achromatopsia is a rare autosomal recessive form of complete color blindness that affects about
Achromatopsia was first recorded on Pingelap in the
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GENETIC ANALYSIS: AN INTEG. APP. W/MAS
- As discussed in the text, almost 5% of Caucasians carry a recessive gene for cystic fibrosis. Until recently, most people with cystic fibrosis died in childhood or early adulthood. Why is cystic fibrosis so frequent in spite of the fact that until recently it was usually lethal?arrow_forwardIs it possible for both males and females to carry the gene for color blindness?arrow_forwardHeterozygote advantage is an interesting condition in those individuals who have one of each allele (dominant and recessive) have a higher survival rate than those individuals who are either homozygous dominant or homozygous recessive. Sickle-cell anemia is such a genetic disease associated with the recessive allele. Normal homozygous individuals (SS) have normal blood cells that are easily infected with the malarial parasite. Thus, many of these individuals become very ill from the parasite and many die. Individuals homozygous for the sickle-cell trait (ss) have red blood cells that readily collapse when deoxygenated. Although malaria cannot grow in these red blood cells, individuals often die because of the genetic defect. However, individuals with the heterozygous condition (Ss) have some sickling of red blood cells, but generally not enough to cause mortality. In addition, malaria cannot survive well within these "partially defective" red blood cells. Thus, heterozygotes tend to…arrow_forward
- Consider a Droscophilia fly with a genotype of Nn XqYY. The dominant allele of the sex-linked gene specifies a black body and the recessive a white body. The recessive autosomal allele specifies hairy bristles while the dominant allele specifies smooth bristles. i)What is the ploidy of this fly? ii) What would the sex of this fly be? iii)What would the phenotype of this fly be with respect to these two loci?arrow_forwardCystic fibrosis (CF) is an autosomal recessive condition triggered by the overproduction of sticky mucus that clogs the lungs and pancreas. It is a life-threatening disease, but medical advances helped the afflicted to live through adulthood. Betty's mother died from cystic fibrosis, but her father was normal and never had any relative with CF. Her fiancé, Jones, turned out to be a carrier of the CF allele. What are the genotypes of Betty and Jones? 1. Betty: ________________________ 2. Jones: _____________________ They planned to have four children. What is the probability that: 3. all children will be normal 4. at least two will be normalarrow_forwardCystic fibrosis is an autosomal recessive disorder that affects 1 in 3 000 newborns with Caucasian background. It causes thick mucus build up in various organs and can cause damages and problems in respiratory and digestive systems. a) What is the frequency of the cystic fibrosis allele in the Caucasian population? Show all your work and express your answer as a value between 0 and 1 rounded to two decimal places. b) What percentage of the Caucasian population would be carriers for cystic fibrosis? Show all your work and express your answer rounded to two decimal places. c)If two individuals are carriers of the cystic fibrosis allele, what is the probability that they would have a girl without cystic fibrosis? Show all your work (including the Punnett square) and express your answer as a value between 0 and 1 rounded to two decimal places.arrow_forward
- please help me out I can't seem to find the correct answer.arrow_forwardJunctional epidermolysis bullosa (JEB) is a severe skin disorder that results in blisters over the entire body. The disorder is caused by autosomal recessive mutations at any one of three loci that help to encode laminin 5, a major component in the dermal–epidermal basement membrane. Leena Pulkkinen and colleagues described a male newborn who was born with JEB and died at 2 months of age (L. Pulkkinen et al. 1997. American Journal of Human Genetics 61:611–619); the child had healthy, unrelated parents. Chromosome analysis revealed that the infant had 46 normal-appearing chromosomes. Analysis of DNA showed that his mother was heterozygous for a JEB-causing allele at the LAMB3 locus, which is on chromosome 1. The father had two normal alleles at this locus. DNA fingerprinting demonstrated that the male assumed to be the father had, in fact, conceived the child. Q. Assuming that no new mutations occurred in this family, explain the presence of an autosomal recessive disease in the child…arrow_forwardJunctional epidermolysis bullosa (JEB) is a severe skin disorder that results in blisters over the entire body. The disorder is caused by autosomal recessive mutations at any one of three loci that help to encode laminin 5, a major component in the dermal–epidermal basement membrane. Leena Pulkkinen and colleagues described a male newborn who was born with JEB and died at 2 months of age (L. Pulkkinen et al. 1997. American Journal of Human Genetics 61:611–619); the child had healthy, unrelated parents. Chromosome analysis revealed that the infant had 46 normal-appearing chromosomes. Analysis of DNA showed that his mother was heterozygous for a JEB-causing allele at the LAMB3 locus, which is on chromosome 1. The father had two normal alleles at this locus. DNA fingerprinting demonstrated that the male assumed to be the father had, in fact, conceived the child. Q. How might you go about proving your explanation? Assume that a number of genetic markers are available for each chromosome.arrow_forward
- Please do the pedigree in the attached picturearrow_forwardPolydactyly is an autosomal dominant trait that results in the presence of additional digits on the hands and feet. The incidence in Caucasians is approximately 1 in every 1300 births while in Africans and African Americans, the prevalence is 1 in every ~150 births. Fortunately, this trait does not cause any deleterious effects on one's health. Actually, there are a number of individuals who have been successful football players that were born with polydactyly. In 1902, a study found that the allele frequency of the recessive allele (p) was 30% in the local population. Last year, a follow-up study was published which assessed the genotypes of the same local population. The following data were obtained: pp = 10%; Pp = 40%; PP = 50% Use the above information to answer the questions below. Use the word bank for a subquestion when provided. What is the frequency of p (recessive allele) in the follow-up study? Round your answer to the nearest tenth. Did the population evolve?…arrow_forwardSickle cell anemia is caused by a recessive allele at a single gene. As we discussed in class, being a homozygote for the sickle cell allele is almost always lethal, but heterozygotes tend to be resistant against malaria although they have a mild form of anemia. Because of this heterozygote advantage, the allele for sickle cell anemia has a frequency of more than 10% in some human populations. How would present allele frequencies of the sickle cell allele change, if there was no heterozygote advantage or disadvantage (that is, that heterozygotes would be identical to ‘normal’ homozygotes – no malaria resistance, no anemia)? How would the change in sickle cell allele frequencies compare to scenario a (extirpation of malaria)arrow_forward
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