Skin color is often one of the first traits people notice in each other. Studies in zebra fish uncovered a mutation that altered a transport protein and resulted in light-colored fish. This discovery led to the finding that the same gene in humans has a strong influence on skin pigmentation in many populations.   The allele of the human transport protein associated with light skin is found almost exclusively in Europeans. The other common allele, which appears to be the ancestral allele, is found in Africans. Explain how you think the allele present in Europeans came to be so common in this population. Select all that apply.   A. A mutation must have occurred in the population ancestral to modern Europeans after their migration to Europe.    B. A mutation must have occurred in the population ancestral to modern Europeans before their migration to Europe.    C. A mutation must have occurred in the population ancestral to modern Europeans either before or after their migration to Europe.    D. The same mutations have occurred very often, so the allele became more and more frequent until it predominated in this population.    E. This mutation gave a reproductive advantage to p

Read the following passage carefully about some aspects of genetics involving a certain species of Drosophila and then answer the following questions in parts  The gene for the production of eye colour in this species of fruit fly can be expressed as either normal red-eyes or as brown-eyes. The allele for the normal red eyes is dominant to that of brown, and is transmitted in normal Mendelian fashion. A gene involved with body colour in this species of fruit fly is located on the non-homologous portion of the X chromosome, and has two alleles, grey and yellow, where the grey allele is dominant to yellow. The two genes are NOT linked.   a) Produce a key to clearly show the nature of the alleles associated with the eye colour in this species of Drosophila, and in each case justify your choice of letters and / or style of presentation to best depict the genetics involved.    b) State the type of genetics involved in terms of body colour, justifying your answer with the evidence from…

Nancy Jones is a doctor who specializes in genetic diseases. For many years she has been studying populations of people who have Huntington’s disease. Dr. Jones has a special interest in Huntington’s disease because her mother died of this disease after many years living in a wheelchair. Dr. Jones’s father does not appear to have the disease. She has developed a test that can detect the dominant Huntington’s gene before symptoms appear and she has performed this test on many people. This test involves mapping a person’s genome to determine if the dominant Huntington’s gene is present. Dr. Jones is unsure if she should take the test herself as it will not prevent the disease from developing, only give the person advanced warning of the disease. Nancy Jones has a sister. Draw a pedigree chart that maps the disease through this family. Make sure to indicate those family members that have the disease, those that do not have the disease and those whose status is unknown.  If you were Nancy…

"Coat color in rats varies from white to black and includes many shades of gray in between. If the number of different coat colors possible is 9, how many genes are involved? "

Alzheimer’s is a progressive neurological disorder resulting in dementia and memory loss that occurs in 10% of the US population older than 65. In the 1990s, several researchers showed evidence that the allele of a cholesterol precursor gene, APO E4, increased risk of developing the disorder compared to APO E2 or APO E3. This was especially pronounced if patients carried two alleles of APO E4. However, not all people with APO E4 develop the disorder and some without it will present with Alzheimer's nevertheless. This suggests other genes influence development of the disease. Current research has elucidated dozens of genes that interact with APO E4 pathways in hundreds of ways. As many as 27 of the interactions are epistatic, with some as dominant epistasis and some as recessive epistasis. In addition, some of the gene candidates for non-APO E4 Alzheimer’s have other relationships such as dominant, codominant or incomplete dominant. No reliable cure currently exists for Alzheimer’s…

The hairless gene allele, H, in fruit flies, causes fruit flies to lack sensory hairs.  The H allele is dominant; the recessive allele, h, causes flies to have normal sensory hairs.  The dominant allele is lethal when homozygous. A second gene, suppressor of Hairless, Su(H), can block the phenotype of hairless. The dominant allele, Su(H), prevents the H allele from causing its phenotype, resulting in flies with sensory hairs.  The dominant Su(H) allele is also lethal when homozygous. The recessive allele, su(H), allows the H allele to cause its phenotype.  The Su(H) allele does not affect with the h allele. If you crossed a normal hair fly (of genotype H h Su(H) su(H) ) with another normal hair fly (of genotype H h Su(H) su(H) ), what proportions  or ratios of genotypes and phenotypes would you expect to observe in the offspring? Show your work.

Sickle cell anemia is a genetic disease most common in those of African ancestry that results from the mutation of a single basepair. This mutation results in a change to the hemoglobin protein. In this experiment, “S” will represent the normal allele and “s” thesickle allele. They are codominant alleles. Therefore, SS is normal, Ss is not fatal but mildly symptomatic, and ss is debilitating,painful, and often fatal. After hundreds or even thousands of generations, both alleles are still common in those of African ancestry. How would you explain this?

The questions below all refer to the following pedigree. The locus for allele D/d determines how cilia function within the body. Mutations at this allele cause abnormal ciliary function, resulting in a clinical disorder characterized by frequent respiratory infections (including in the ears, sinuses, and lungs), as well as infertility. In the pedigree, black circles/squares represent individuals affected by the disorder. White circles/squares represent unaffected individuals. Remember, if a trait is rare in a population (such as this one), we assume individuals marrying into the family are NOT carriers unless the information provided indicates otherwise. A1 A2 II B1 B2 B3 B4. B5 B6_ II C1. C2 C3. C4. C5 IV D1. D2, D4 . D5 Individuals C2 and C3 are considering having additional children. However, having already had a child with this disorder, they visit a genetic counselor to determine what the probability is that their future child would have the disorder. If C2 and C3 have another…