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Free Classroom Resources from HHMI for Teaching Evolution, Part 2. Megan Stine stinem@hhmi.org June 19, 2014. Evolution: Behind the Scenes. Evolving Switches, Evolving Bodies. Film guides Virtual lab Classroom activities: Using Genetic Crosses to Analyze a Stickleback Trait
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Free Classroom Resources from HHMI for Teaching Evolution, Part 2 Megan Stine stinem@hhmi.org June 19, 2014
Evolving Switches, Evolving Bodies • Film guides • Virtual lab • Classroom activities: • Using Genetic Crosses to Analyze a Stickleback Trait • Modeling the Regulatory Switches of the Pitx1 Gene in Stickleback Fish
Evolving Switches, Evolving Bodies Film • http://www.hhmi.org/biointeractive/making-fittest-evolving-switches-evolving-bodies
Which phenotype is dominant? • Assumption: single-gene trait, 2 alleles, normal dominance • Cross between a marine stickleback and one from Bear Paw Lake • Parents are homozygous • F is dominant, f is recessive
Predict the results of the crosses 1st generation 2nd generation Ff Ff Ff FF Ff Ff Ff ff Pelvic spines present:absent = Pelvic spines present:absent = 1:0 3:1 1:3 0:1
Sorting by Phenotype With pelvic spines Without pelvic spines
Do the data support your hypothesis? • Sort the F1 cards: • Fish with pelvic spines • Fish without pelvic spines • Sort the F2 cards • Ratio of fish with:without pelvic spines in F1? • Ratio of fish with:without pelvic spines in F2? 1:0 3.4:1 Was our initial assumption correct? Is this a single-gene trait? Was your hypothesis correct? Which phenotype is dominant?
Natural Selection in Humans • Film guides • Classroom resources: • Nature of Science • Mendelian Genetics, Pedigrees, and Chi-square Analysis • How Fibers Form • Population Genetics
Natural Selection in Humans Film • http://www.hhmi.org/biointeractive/making-fittest-natural-selection-humans
Mendelian Genetics Activity • Punnett squares • Pedigree analysis • Pedigree creation • Chi-square analysis • Data prediction • Important notes: • A is normal allele • S is sickle cell allele • AA has normal RBC phenotype • AS has sickle cell trait • SS has sickle cell disease
Question #1: Intro Punnett • Chance of normal RBC in high and low oxygen? • Chance of SCD? • Chance of 3 children with SCD? • Chance of 2 children with sickle cell trait and 1 with SCD? • Child without SCD, what chance he/she has trait? 1/4 1/4 1/64 1/16 2/3 AS AA AS SS
Question #6: Intro Pedigree • Genotype of: • 1st gen male? • 2nd gen daughter? • Individual #3? • If family moves to lowlands of E. Africa, 4/5 males will have two genetic advantages. What are they? AS SS AS
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