BackgroundProblem N° 7Objective: To illustrate the use of testcrosses to establish unknown genotypes.In dogs (Canis familiaris), there is a hereditary deafness caused by the recessive gene d. A kennel owner has amale dog (Fido, of course) that she wants to use for breeding purposes. She comes to you for genetlc advice. Thedog can hear, so you know that his genotype is either DD or Dd.For this problem, you are allowed to usePunnett squares or pedigrees.If Fido's genotype were Dd, the owner would not use him for breeding so that the deafness gene will not bepassed on. The dog's genotype can be ascertained via a test-cross with a deaf female (dd). Draw Punnett squaresor pedigrees to illustrate these two possible crosses.A test cross uses an individual whosegenotype we can be certain of, i.e., ahomozygous recessive for a particular trait.Such organism is crossed with one whosegenotype we do not know (remember thehomozygous recessive always express therecessive phenotype). In this case, a dd dogwill be deaf and a hearing dog can be DD orDd (i.e., D- represents both homozygousdominant and heterozygous until thegenotype is determined).O000ofThe results of a test cross will be eitherdd X DD → All Dd (all hearing), the unkonwngenotype is DD;a. Use fractions or decimals to indicate proportions: In each case, what proportion of the offspringwould be expected to be hearing?ordd X Dd > % Dd + % dd (half hearing,half deaf), the unknowngenotype is Dd.b. What proportion would be expected to be deaf?So, the proportion of hearing dogs willindicate the unknown genotype.c. How could you tell the genotype of the male dog (in parental generation P)?d. Also, using a Punnett square, how would you explain to the kennel owner that two hearing dogscould produce deaf offspring? Indicate to the kennel owner what kind(s) of gametes (ova or sperm)could hearing dogs produce to conceive a deaf puppy

For showing the Mandellion crosses where the genotypes and phenotypes of the offspring can be…

In dogs (Canis familiaris), there is a hereditary deafness caused by the recessive gene d. A kennel owner has a male dog (Fido, of course) that she wants to use for breeding purposes. She comes to you for genetlc advice. The dog can hear, so you know that his genotype is either DD or Dd. If Fido's genotype were Dd, the owner would not use him for breeding so that the deafness gene will not be passed on. The dog's genotype can be ascertained via a test-cross with a deaf female (dd). Draw Punnett squares or pedigrees to illustrate these two possible crosses. O000 O a. Use fractions or decimals to indicate proportions: In each case, what proportion of the offspring would be expected to be hearing? b. What proportion would be expected to be deaf? c. How could you tell the genotype of the male dog (in parental generation P)? d. Also, using a Punnett square, how would you explain to the kennel owner that two hearing dogs could produce deaf offspring? Indicate to the kennel owner what kind(s) of gametes (ova or sperm) could hearing dogs produce to conceive a deaf puppy

In dogs (Canis familiaris), there is a hereditary deafness caused by the recessive gene d. A kennel owner has a male dog (Fido, of course) that she wants to use for breeding purposes. She comes to you for genetlc advice. The dog can hear, so you know that his genotype is either DD or Dd. If Fido's genotype were Dd, the owner would not use him for breeding so that the deafness gene will not be passed on. The dog's genotype can be ascertained via a test-cross with a deaf female (dd). Draw Punnett squares or pedigrees to illustrate these two possible crosses. O000 O a. Use fractions or decimals to indicate proportions: In each case, what proportion of the offspring would be expected to be hearing? b. What proportion would be expected to be deaf? c. How could you tell the genotype of the male dog (in parental generation P)? d. Also, using a Punnett square, how would you explain to the kennel owner that two hearing dogs could produce deaf offspring? Indicate to the kennel owner what kind(s) of gametes (ova or sperm) could hearing dogs produce to conceive a deaf puppy

Human Anatomy & Physiology (11th Edition)

11th Edition

ISBN:9780134580999

Author:Elaine N. Marieb, Katja N. Hoehn

Publisher:Elaine N. Marieb, Katja N. Hoehn

Chapter1: The Human Body: An Orientation

Section: Chapter Questions

Problem 1RQ: The correct sequence of levels forming the structural hierarchy is A. (a) organ, organ system,...

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