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Unformatted text preview: BIO 325 Genetics Homework #3 Fall 2008, Dr. Moon Name: ____________KEY_________ UTEID_________________Class time:_______ This assignment is due in class on Friday, Sept 19. The assignment is worth 20 points. Please show your work for full credit. 1. Hereditary deafness in dogs is caused by a recessive gene, “d.” A kennel owner has a male dog that she wants to use for breeding purposes. The dog can hear, but the owner wants to make sure the deafness gene is not passed on. She comes to you for help. 1a (0.5pts). What type of female dog would you recommend the owner use initially to mate with the male stud dog to determine if he carries the deafness allele? A dd (deaf) female dog. This is a test cross. 1b (1pt). Draw the Punnett squares to illustrate the outcome of the two possible crosses – what percentage of the offspring would be expected to be hearing or deaf in each case? D d D D d Dd dd d Dd Dd d Dd dd d Dd Dd 50% hear, 50% deaf 100% hear 1c (1pt). How would you use the information in the crosses above to advise the kennel owner regarding the suitability of the male dog for breeding? If half the offspring from the cross with the deaf female dog are deaf, the stud dog is heterozygous and shouldn’t be used. If all of the offspring are hearing, the male dog is homozygous DD and can be used for breeding. 2. We know that if a person has sickle-cell anemia (ss) that in times of high oxygen demand (or stress), the malformed hemoglobin causes red blood cells ‘sickle’ resulting in reduced oxygen transport and clogging of blood vessels. The presence of a malaria parasite in a red blood cell is so stressful it causes the cell to sickle, which kills the parasite before it can multiply and spread to other red blood cells. Therefore, a person who is ss is also “immune” to malaria. Likewise, if a person is Ss and a malaria parasite tries to invade, again the cell will sickle, killing the parasite before it has a chance to reproduce. However, Ss individuals do not normally show the symptoms of sickle cell anemia. You’re in working for Doctors Without Borders in a tropical area where malaria is prevalent and health care is not accessible. In your clinic, you meet a healthy-appearing man and a healthy-appearing woman, parents of a child with sickle cell anemia. They tell you that at home they have seven more children (so eight children in all). You have yet not met and examined the other children....
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This note was uploaded on 10/05/2008 for the course BIO 325 taught by Professor Saxena during the Fall '08 term at University of Texas.
- Fall '08