Concept explainers
To analyze:
The human melanocortin
Introduction:
The human skin color or pigmentation results from both the parents’ genetic makeup and ultraviolet radiation. The evolution of skin shows the natural selection in order to regulate the penetration of the UV rays into the skin and also controlling its biochemical effects.
Melanin is the pigment that determines the skin color, and it is produced by melanocytes.
The
Eumelanin tends to have black or brown pigmentation, and most often, eumelanin protects skin from UV radiation in sunlight.
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Genetic Analysis: An Integrated Approach (3rd Edition)
- Which of the following best explains how individuals who inherit phenylketonuria alleles can avoid the symptoms of this disease (mental impairment, foul smelling urine)? It exhibits variable expressivity. The expression of this disease depends on the environment. If the individual removes phenylalanine from their diet they can avoid the disease entirely. PKU alleles are epistatic to alleles of another gene, which acts downstream in phenylalanine metabolism. These individuals supplement their diets with enzymes that break-down phenylalanine.arrow_forwardAPOE gene has been found to be a major contributor to sporadic Alzheimer's disease (AD), by acting as an age-of-onset modifier for the common relatively late-onset forms of the disease. Among four alleles causing early onset of AD, the epsilon4 allele (APOE4) disrupts this function. If you generate transgenic monkeys in which the normal allele of APOE gene is knocked out, what phenotype will you expect for those knockout monkeys? A. The APE mRNA expression will be completely suppressed. B. They slow down the development of AD. C. They develop AD early. D. They don't show any AD symptom.arrow_forwardSteven Frank and Laurence Hurst argued that a cytoplasmically inherited mutation in humans that has severe effects in males but no effect in females will not be eliminated from a population by natural selection because only females pass on mtDNA (S. A. Frank and L. D. Hurst. 1996. Nature 383:224). Using this argument, explain why males with Leber hereditary optic neuropathy are more severely affected than females.arrow_forward
- Spherocytosis is an inherited blood disease in which erythrocytes (red blood cells) are spherical instead of biconcave. This condition is inherited in a dominant fashion, with ANK1 (the nonfunctional mutant allele) dominant to ANK1+. In people with spherocytosis, the spleen recognizes the spherical red blood cells as defective and removes them from the bloodstream, leading to anemia; this removal occurs with different efficiency in different people. Some people with spherical erythrocytes suffer severe anemia, some have mild anemia, and others do not have any symptoms of anemia. When 2400 people with the genotype ANK1/ANK1+ were examined, it was found that all of them had spherical erythrocytes, 2250 had anemia of varying severity, and 150 had no anemia symptoms. The ANK1/ANK1 genotype is never observed. Which evidence suggests that spherocytosis is incompletely penetrant?arrow_forwardForward Genetics Analysis uses a variety of beneficial approaches to identify never before described genes. For each of the following approaches or outcomes, briefly (maximum 2 sentences) discuss in your own words, their purpose in Forward Genetics Analysis. c) Mendelian ratios d) Genetic screenarrow_forwardFor three years, Gunther Schlager and Margaret Dickie estimated theforward and reverse mutation rates for five loci in mice that encodevarious aspects of coat color by examining more than 5 million mice forspontaneous mutations (G. Schlager and M. M. Dickie. 1966. Science151:205–206). They detected the following numbers of mutations at thedilute locus: Gametes examined Mutations detectedForwardmutations 260,675 5Reversemutations 583,360 2 Calculate the forward and reverse mutation rates at this locus. If thesemutations rates are representative of rates in natural populations of mice,what would the expected equilibrium frequency of dilute mutations be?arrow_forward
- In your attempts to identify a genetic basis for rheumatoid arthritis in humans, you have DNA samples from three large unrelated families in which individuals with varying severity of rheumatoid arthritis are found. From your analysis of various SNPs, you find that the same four unlinked loci consistently show a correlation with the most severe cases from all three families. Based on your observations, which of the following hypotheses best describes the genetic control of rheumatoid arthritis? ос Rheumatoid arthritis is the result of phenocopy by the environment Different genes regulate the disease in different families Rheumatoid arthritis is controlled by a single X-linked recessive trait Rheumatoid arthritis is controlled by polygenic (or quantitative) traits Rheumatoid arthritis is controlled by a single autosomal dominant traitarrow_forwardIn a study, an undergraduate student discovered a new enzyme involved in the metabolism of serotonin. This enzyme is made up of 3 subunits of the same protein. To characterize this enzyme, the student used genetic approaches to induce mutations in the coding region of the gene that codes for this protein and performed crosses to measure the effects of genotypes on enzyme activity. A) Indicate directly in the diagram (via a bar graph) the predicted relationship between genotype and enzyme activity. (Al represents the wild-type allele, A2 represents the mutant allele). A2A2 A1A2 A1Α1 B) Explain the reasoning for your prediction. Enzyme Activityarrow_forwardThe gene known to be mutated in cases of Agammaglobulinemia 2 (which is inherited in an autosomal recessive pattern) is the immunoglobulin lambda like polypeptide 1 (IGLL1 ENSG00000128322). What is known about the gene is recorded here: http://www.ensembl.org/Homo_sapiens/Gene/Summary?g=ENSG00000128322;r=22:23573125-23580302 Please navigate to the link above to answer the following question: Using the left-hand menu to view the sequence for IGLL1, what are the last 12 nucleic acid bases of exon 1?arrow_forward
- The gene known to be mutated in cases of Agammaglobulinemia 2 (which is inherited in an autosomal recessive pattern) is the immunoglobulin lambda like polypeptide 1 (IGLL1 ENSG00000128322). What is known about the gene is recorded here: http://www.ensembl.org/Homo_sapiens/Gene/Summary?g=ENSG00000128322;r=22:23573125-23580302 Please navigate to the link above and click, 'show transcript table', to answer the following question: What is the size in amino acid residues of the IGLL1 transcript named IGLL1-203? NOTE: Please give your answer as a number, not a word, and do not type the units.arrow_forwardThe gene known to be mutated in cases of Agammaglobulinemia 2 (which is inherited in an autosomal recessive pattern) is the immunoglobulin lambda like polypeptide 1 (IGLL1 ENSG00000128322). What is known about the gene is recorded here: http://www.ensembl.org/Homo_sapiens/Gene/Summary?g=ENSG00000128322;r=22:23573125-23580302 Please navigate to the link above and click 'show transcript table' to answer the following question: What is the NCBI accession number (including the version) of the RefSeq Match for the transcript IGLL1-202? ANSWER: The NCBI accession number (including the version) of the RefSeq Match for the transcript IGLL1-202 is "Blank 1".arrow_forwardThe gene known to be mutated in cases of Agammaglobulinemia 2 (which is inherited in an autosomal recessive pattern) is the immunoglobulin lambda like polypeptide 1 (IGLL1 ENSG00000128322). What is known about the gene is recorded here: http://www.ensembl.org/Homo_sapiens/Gene/Summary?g=ENSG00000128322;r=22:23573125-23580302 Please navigate to the link above to answer the following question: According to the web site above, how many phenotypes is IGLL1 associated with? ANSWER: IGLL1 is associated with Blank ... phenotypes.arrow_forward
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