Genetics Week 5
Genetics Week 5 BIOL/PBIO 3333
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This 4 page Class Notes was uploaded by Lauran Notetaker on Sunday February 21, 2016. The Class Notes belongs to BIOL/PBIO 3333 at University of Oklahoma taught by Dr. Jim Thompson in Winter 2016. Since its upload, it has received 10 views. For similar materials see Genetics in Biology at University of Oklahoma.
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Date Created: 02/21/16
February 15, 2016 IV. Chromosomes A. Prokaryote vs Eukaryote B. Statistical Testing 1. Null Hypothesis 2. Chi Square C. Chromosome Mapping 1. 2-point Mapping 2. Physical Evidence of Recombination Prokaryotes 1. Generally haploid 2. Single “chromosome” or linkage group 3. Linkage group often circular 4. DNA relatively free of protein 5. Coding capacity: Example = E. Coli about 4.2 x 10^6 bp 6. Lack of membrane bound organelles Eukaryote 1. DNA is in the form of nucleoprotein = DNA - histone protein complex 2. Each chromosome Homologous pair of chromosomes Chi Square Application for Statistical Testing Used to compare data in categories X^2 = chi square = (Sigma) (O - E)^2 / E when data are in categories = a test to measure the ﬁt between your data and your null hypothesis Ex. Boy vs Girl BB vs Bb Null hypothesis = equal frequency of boy and girls d.f. - Degrees of freedom February 17, 2016 IV. Chromosomes C. Chromosome Mapping 1. 2-point Mapping 2. Physical Evidence of Recombination 3. 3-point Mapping a. Gene order b. Interference 4. Special Cases a. Cell Fusion b. Tetrad Analysis c. Mitotic Recombination Recombination is random occurs 1-3 times per chromosome changes the way alleles are connected to centromere dp b Observed Expected (O-E)^2 (Sigma)(O-E)^2 / E dpb dpdp bb 32 25 7^2 49/25 ++ dp+ b+ 33 25 -9^2 81/25 dp+ dpdp b+ 16 25 -6^2 36/25 +b dp+ bb 19 25 8^2 64/25 100 chi square 9.2 number of d.f. categories - 1 = 3 percentage crossing over 16 + 19 = 35 = 35% or 25 map units (cM or mu) 100 100 1% crossing over = 1 map unit When the numbers are clearly not 1:1:1:1, don't waste time by doing a Chi Square Test. Go directly to calculating the map distance from the data Classical Experiment by Curt Stern - conﬁrmed that the exchange of genetic traits in a dihybrid was associated with physical exchange between sister chromatids cis-linkage - same strand trans-linkage - opposite strand (across) February 19, 2016 IV. Chromosomes C. Chromosome Mapping 1. 2-point Mapping 2. Physical Evidence of Recombination 3. 3-point Mapping a. Gene order b. Interference 4. Special Cases a. Cell Fusion b. Tetrad Analysis c. Mitotic Recombination Tracing pattern genes 2-point require heterozygous, inherit from dihybrid parent Associated with physical landmarks Double crossover - least common because 2 independent crossovers have to have occurred gene in middle changed linkage Largest distance is 50% mu effectively unlinked * The bottom row says: class + + + crossover + + + Parental va gl v 235 0 +7 + 2 Double + gl + 7 the middle gene is the one that va + v 4 changes Observed is 10/2880 = 0.35% Expected is 0.053(0.203) = 1.08% = 31/2880 degree of interference 1- (0.35/1.08) = 0.68 = 68% were interfered with
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