Learning about pedigrees
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Learning about pedigrees

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    Learning about pedigrees Learning about pedigrees Presentation Transcript

    • Learning About Pedigrees
    • 2. A chart used to follow genetic traits in a family 2. Can be used to determine who a trait is inherited from 2. Can be used to determine if a trait is dominant,1. Pedigree recessive, X linked or some other mode of inheritance.
    • Example of a Pedigree!
    • 1. Constructing a Pedigree2. Males represented by squares2. Females are represented by circles2. A marriage is a line between 2 shapes2. Offspring are shown using a line from a marriage
    • 2. Shaded shapes show people that have a trait2. Unshaded shapes do not show the trait2. Sometimes a heterozygous person is half-shaded
    • Practice – Write the answers to these questions on a piece of paper.1. In this pedigree, which numbers are females?2. Which numbers are male?3. How many brothers does # 11 have?4. Who is # 9 married to?5. How many children does couple 1 and 2 have?6. Which are married?7. Which show the trait for which the pedigree was constructed?8. Guess: do you think this trait is inherited as a dominant allele or a recessive allele? WHY?
    • Practice – Write the answers to these questions on a piece of paper. Use the numbers to show which people are the answers to each question1. In this pedigree, which numbers are females? 1,4,7,8,10,11,13,15,16,17,18,192. Which numbers are male? 2,3,5,6,9,12,14,203. How many brothers does # 11 have? 1 (#12)4. Who is # 9 married to? 85. How many children does couple 1 and 2 have? 36. Which are married? # 4 and #67. Which show the trait for which the pedigree was constructed? 2,6,9,11,16,208. Guess: do you think this trait is inherited as a dominant allele or a recessive allele? WHY?
    • Try using a pedigree to determine genotypes…..• If this pedigree follows a trait that is coded for by a recessive allele….• What is the genotype of parent 1? A = dominant allele a= recessive allele• Parent 2?• The daughter?• The son?
    • Try using a pedigree to determine genotypes…..• If this pedigree follows a trait that is coded for by a recessive allele….• What is the genotype of parent 1? Aa A = dominant allele• Parent 2? Aa a= recessive allele• The daughter? aa• The son? A__ (we can’t know the second allele yet)
    • Figure out if the trait is dominant or recessive……• Do you think this pedigree shows a dominant trait or a recessive trait?• Explain why and draw a punnett square to support your answer.
    • • In this pedigree, the trait must be dominant, and the parents must both be heterozygous A aA AA Aaa Aa aa
    • Summarize……• List several types of information that pedigrees can be used for.• Explain how a pedigree is constructed• Explain whether the pedigree here shows a dominant trait or a recessive trait and explain why you think so using a punnett square.
    • Try making a pedigree!• The gene which results in Achondroplasia is dominant. Use the numbers to make a pedigree which follows the genotypes of each person in this picture. You can use the numbers to show who is who on the pedigree. 3 4 5 6 1 2
    • Albinism is inherited as a recessive allele. In the figure above, assumingthat persons from the general population are not heterozygous foralbinism (Aa), what are the genotypes of all persons whose genotypesare known?
    • Case Study• Learn about a disorder called Alcaptonuria (click here).• Read the fact sheet and determine the following :• What are the SYMPTOMS of alcaptonuria?• What are the CAUSES of alcaptonuria?• What test determines whether a patient has alcaptonuria?• What are some effective treatments for alcaptonuria?
    • The StoryA new baby is born into the family!! Baby Jenna appears health and strong, but nurses notice that her diaper has turned a disturbing brown/black color.After testing, the doctor diagnoses the child with alcaptonuria.The family now needs to know more about the disease, so you are called in to help.Your goals: 1. Determine who in the family has the disease 2. Design a pedigree to help the family see how the trait has moved through the family. 3. Explain how the trait is inherited in a way that the family understands.
    • Start your research• 1. Test the urine of the family.  Request urine samples of family members  Add the test solution to the tube  Record the results.• 2. Design a pedigree and indicate who is affected and who is not (hint: you may benefit from designing the pedigree before the test and then shading in the affected family members later. )• 3. Fill in the genotypes of each of the family members on the pedigree.
    • • The family: John and Lucy are the parents of baby Jenna• John has 1 sister named Suzanne• John’s parents are Steven and Martha• Lucy’s parents are David and Ann• Lucy has a brother, Randy and a sister Lynne