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Human Genetics Lab

Human Genetics Lab . When Students Are the Subjects…… . Loci, Genes and Alleles. Locus = area on chromosome where gene is located (plural = loci) Gene = sequence of DNA that codes for a protein, gives rise to physical trait Alleles = alternative forms of a gene

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Human Genetics Lab

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  1. Human Genetics Lab When Students Are the Subjects……

  2. Loci, Genes and Alleles • Locus = area on chromosome where gene is located (plural = loci) • Gene = sequence of DNA that codes for a protein, gives rise to physical trait • Alleles = alternative forms of a gene • Dominant allele masks other alleles • Recessive allele is masked Locus 1 Locus 2 Locus 3

  3. Genotype and Phenotype

  4. Earlobe Attachment

  5. Solving Genetics Problems • Convert parental phenotypes to genotypes --may need to use info about grandparents or children already born to complete these genotypes • Use Punnett Square to determine genotypes of offspring • Convert offspring genotypes to phenotypes

  6. Genetics Problem 2, p. 104 George has attached ear lobes. Laura has free earlobes, but she is heterozygous for this trait. What are the chances of their child having free earlobes? Genotype for George Genotype for Laura ee Ee

  7. e e e e Homozygous parents can only pass one form of an allele to their offspring.

  8. Heterozygous parents can pass either of two forms of an allele to their offspring. E e E e

  9. E e e e Genetics Problem 2, p. 104 George has attached ear lobes. Laura has free earlobes, but she is heterozygous for this trait. What are the chances of their child having free earlobes? Genotype for George Genotype for Laura ee Ee ee Ee 50% free earlobes50% attached earlobes Ee ee

  10. EH Eh eH eh EH Eh eH eh Genetics Problem 12, p. 107 Both Willy and Ethyl are heterozygous for earlobe attachment and also for hitchhiker’s thumb. What are the chances of a child with……attached earlobes and a hitchhiker’s thumb?…free earlobes and no hitchhiker’s thumb? Genotype for Willy Genotype for Ethyl EeHh EeHh

  11. EH Eh eH eh EEHH EEHh EeHH EeHh EH Eh eH eh EEHh EEhh EeHh Eehh EeHH EeHh eeHH eeHh EeHh Eehh eeHh eehh eehh = 1/16 …attached earlobes and a hitchhiker’s thumb? …free earlobes and no hitchhiker’s thumb? E_H_ = 9/16

  12. Lab Today • Simple Inheritance (12 traits) • The “Which Classmate Shares the Most Traits with You?” Game: Four student volunteers – single elimination • “Direct Comparisons with Individuals” – four classmates and find % of traits shared • Complex Inheritance: Height, ABO blood type • Solving Genetics Problems with Punnett squares

  13. Simple Inheritance Determine your phenotype and potential genotype for each trait. At a specified time, your instructor will conduct a class tally for all traits.

  14. Direct Comparisons with Individuals

  15. Sex-Influenced Traits Change Dominance Pattern by Gender

  16. Height Distribution of Class Members Have a partnermeasure your height in cm. We will do a class tally to group the data as shown in this table.

  17. Genetic Patterns for Blood Type Codominance: Neither allele masks the other so that effects of both alleles are observed in heterozygotes without blending Multiple Alleles: Three or more alleles exist for one trait Note: A diploid individual can only carry any two of these alleles at once.

  18. Multiple Alleles and Codominance ABO Blood Type in Humans A=B> o A and B are codominant. Aand B are completely dominant over o.

  19. Type A Type B A and B Neither • Type • Genotype • Antigen on RBCs • Anti-bodies • Re-ceives • Donates • Freq Human ABO Blood Types • A • AA or Ao • B • A or O • A or AB • 40% • B • BB or Bo • A • B or O • B or AB • 10% • AB • AB • Neither • AB, A,B, O(universal) • AB(universal) • 4% • O • oo • Both • O • O,AB,A,B(universal) • 46% Codominance is observed for Type AB Blood since the products of both the A and B allelesare found on the cells.

  20. ? Paternity Testing before DNA Fingerprinting Joan Barry Charlie Chaplin Type A Blood Type O Blood Possible GenotypesAA Ao Genotypeoo Baby Type B Blood Possible GenotypesBB Bo X Can Charlie Chaplin be the father?

  21. Worksheet • Complete pages 99-105 from lab manual • Be sure your instructor checks your completed worksheet before you leave the lab. Partial completion will be accepted for students who have entered and evaluated all the necessary data and attempted some of the genetics problems.

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