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Population Genetics Ch. 23 and Beyond; Lab/Lecture Same Math Calisthenics I Ladybug Population Generation One Calculate TOTAL # A AA = 200 Aa = 100 aa = 200 Calculate Total # a Math Calisthenics I Ladybug Population Generation One Calculate TOTAL # A (200 X 2) + (100 X 1) Total A = 500 AA = 200 Aa = 100 aa = 200 Calculate Total # a (200 X 2) + (100 X 1) Total a = 500 Calculate TOTAL # A (200 X 2) + (100 X 1) Total A = 500 Convert to % A Calculate Total # a (200 X 2) + (100 X 1) Total a = 500 Convert to % a Calculate TOTAL # A (200 X 2) + (100 X 1) Total A = 500 Convert to % A 500/1000 = 0.5 (AVOID USING 50%) Calculate Total # a (200 X 2) + (100 X 1) Total a = 500 Convert to % a 500/1000 = 0.5 (AVOID USING 50%) Ladybug Population Generation Two Calculate TOTAL # A AA = 300 Aa = 100 aa = 100 Calculate Total # a Ladybug Population Generation Two Calculate TOTAL # A (300 X 2) + (100 X 1) Total A = 700 AA = 300 Aa = 100 aa = 100 Calculate Total # a (100 X 2) + (100 X 1) Total a = 300 Calculate TOTAL # A (300 X 2) + (100 X 1) Total A = 700 Convert to % A Calculate Total # a (100 X 2) + (100 X 1) Total a = 300 Convert to % a Calculate TOTAL # A (300 X 2) + (100 X 1) Total A = 700 Convert to % A 700/1000 = 0.7 Calculate Total # a (100 X 2) + (100 X 1) Total a = 300 Convert to % a 300/1000 = 0.3 In the language of population genetics, p = % DOMINANT ALLELES q = % RECESSIVE ALLELES p Ladybug Generation 1 Ladybug Generation 2 q In the language of population genetics, p = % DOMINANT ALLELES q = % RECESSIVE ALLELES Ladybug Generation 1 Ladybug Generation 2 p q 0.5 0.5 0.7 0.3 Class brainstorming - what might cause a shift in allele frequencies (% A/a or p/q)? Hardy-Weinberg (1908) predicted allele frequencies would NOT change if… Hardy-Weinberg (1908) predicted allele frequencies would NOT change if… LARGE POPULATION Genetic Drift: allele % fluctuations due to TOO SMALL SAMPLE - BOTTLENECK Hardy-Weinberg (1908) predicted allele frequencies would NOT change if… LARGE POPULATION NO MIGRATION Hardy-Weinberg (1908) predicted allele frequencies would NOT change if… LARGE POPULATION NO MIGRATION NO MUTATIONS Hardy-Weinberg (1908) predicted allele frequencies would NOT change if… LARGE POPULATION NO MIGRATION NO MUTATIONS MATING RANDOM Hardy-Weinberg (1908) predicted allele frequencies would NOT change if… LARGE POPULATION NO MIGRATION NO MUTATIONS MATING IS RANDOM NO SELECTION FOR CERTAIN TRAITS Predicting and Detecting Variation For dom/rec traits, which is only genotype you know for certain based on phenotype? HW developed a useful predictive equation: p2 + 2pq + q2 = 1 Let’s say you want to predict the # carriers of a new recessive disease allele. Math Calisthenics II Epidemiology Data from Monmouth aa = 1600/10,000 Calculate p Calculate q Calculate p2 & 2pq Let’s say you want to predict the # carriers of a new recessive disease allele. Math Calisthenics II Epidemiology Data from Monmouth aa = 1600/10,000 Calculate p Calculate q q2 = 1600/10,000 = 0.16 = 0.4 = q Calculate p2 & 2pq Let’s say you want to predict the # carriers of a new recessive disease allele. Math Calisthenics II Epidemiology Data from Monmouth aa = 1600/10,000 Calculate p p + q = 1… SO 1 - 0.4 = p 0.6 = p Calculate q q2 = 1600/10,000 = 0.16 = 0.4 = q Calculate p2 & 2pq Let’s say you want to predict the # carriers of a new recessive disease allele. Math Calisthenics II Epidemiology Data from Monmouth aa = 1600/10,000 Calculate p p + q = 1… SO 1 - 0.4 = p 0.6 = p Calculate q q2 = 1600/10,000 = 0.16 = 0.4 = q Calculate p2 & 2pq p2 = (0.6)(0.6) = 0.36 2pq = 2(0.6)(0.4) = 0.48 Check Work! Does p2 + 2pq + q2 = 1? What does this data mean??? Lab: Aside from disease/carrier status, why is knowing heterozygosity important? Many alleles display polymorphisms detectable at DNA OR PROTEIN LEVEL Now consider sickle cell polymorphism… Prokaryotes make protective nucleases called RESTRICTION ENZYMES (20.1-2) e.g. DdeI cuts CTTAG - distinguishes hemoglobin alleles (Fig. 20.9) In lab, you will explore protein gels of enzyme complexes to predict genotypes. Consider that some enzymes are made of single proteins - MONOMERS Hom/Dom Hom/Rec Het/Dom 1 BAND 1 BAND 2 BANDS Others are made of multiple proteins e.g. DIMERS, 2 FOLDED CHAINS Hom/Dom Hom/Rec Het/Dom 1 BAND 1 BAND 3 BANDS Population Genetics and Evolution Do any populations meet HW conditions? RARELY AND NOT FOR LONG Evolution: CHANGES in the genetic makeup of a population OVER TIME