BIOL 3451 1st Edition Lecture 4 Outline of Last Lecture I. 2.4 Meiosis Reduces the Chromosome # from Diploid to Haploid in Germ Cells and Spores (cont)II. 2.5 The Development of Gametes Varies in Spermatogenesis Compared to OogenesisIII. 2.6 Meiosis Is Critical to the Successful Sexual Reproduction of All Diploid OrganismsIV. 2.7 Electron Microscopy Has Revealed the Physical Nature of Mitotic and Meiotic ChromosomesV. Chapter 3: Mendelian GeneticsVI. 3.1 Mendel Used a Model Experimental Approach to Study Patterns of InheritanceVII. 3.2 Monohybrid Cross Reveals How One Trait Is Transmitted from Generation to GenerationVIII. Mendel’s Dihybrid Cross Generated a Unique F2 RatioOutline of Current Lecture I. 3.3 Mendel’s Dihybrid Cross Generated a Unique F2 RatioII. 3.4 Trihybrid Cross Demonstrates that Mendel’s Principles Apply to Inheritance of Multiple TraitsIII. 3.5 Mendel’s Work was Rediscovered in the Early Twentieth CenturyIV. 3.6 Independent Assortment Leads to Extensive Genetic VariationV. 3.7 Independent Assortment Leads to Extensive Genetic VariationVI. 3.8 Chi-square Analysis Evaluates the Influence of Chance on Genetic DataVII. 3.9 Pedigrees Reveal Patterns of Inheritance of Human TraitsCurrent LectureI. 3.3 Mendel’s Dihybrid Cross Generated a Unique F2 Ratio- Dihybrid Cross Ratioo Figure 3.5:  Round and yellow are not linked together, they are independently assortedo Figure 3.6 and 3.7 Put a Punnett square in each square of the Punnett square (gives you 16 boxes) You get 9:3:3:1These notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute. This is only true if they independently assort (aren’t linked) Product law: can predict the frequency with which two independent events will occur simultaneously (fig 3.6) Remember Mendel’s 4th postulate: Independent Assortment- Traits assort independently during gamete formation- All possible combos of gametes will form with equal frequency- Monohybrid: separate alleles of mom and dad- Dihybrid: independent assortment of alleles on different loci (spots on a gene)II. 3.4 Trihybrid Cross Demonstrates that Mendel’s Principles Apply to Inheritance of Multiple Traits- Trihybrid Crosso Shows same as dihybrid cross does, but that it also applies to any #  This is good science!o Figure 3.9 (this forked line method easier than Punnett square with many traits)o Table 3.1: math rules…won’t really be calculating, just understand themIII. 3.5 Mendel’s Work was Rediscovered in the Early Twentieth Century- Mendel suggested that heredity resulted in discontinuous variation theory o Slow change from where begano Different idea than what was accepted at that time: offspring blend of parental phenotypes (continuous variation) Blending does occur, but not how they thought Trait can go away and come back-showed that wasn’t as they thoughtIV. 3.6 Independent Assortment Leads to Extensive Genetic Variation- Chromosomal theory of inheritanceo Proposed that separation of chromosomes during meiosis could be the basis for Mendel’s principles of segregation and independent assortment Remember!!!- Segregation: paired unit factors(alleles of same gene) segregate independently during gamete formation Figure 3.10:a,b,c Mendel’s segregation was not entirely correct-more difficult than that Non-homologous chromosmes segregate independentlyV. 3.7 Independent Assortment Leads to Extensive Genetic Variation- Independent assortment: genetic variation, important for evolution- Laws of probabilityo Usually multiply here- Product law: probability of both events occurring is the product of the probability of each individual event- Sum law: states that the probability of obtaining any single outcome, where that outcome can be achieved in two or more events, is equal to the sum of the individual probabilities of all such events (Simpler: add all probabilities of all of the events to get the probability of an outcome)o used to calculate the probability of generalized outcome that can be accomplished in more than one way- Conditional probability: likelihood of the desired outcome when one event depends on another (it is conditional on another)- Binomial theoremo Calculate probability of any specific set of outcomes in large # of potential events (usually computer does this)VI. 3.8 Chi-square Analysis Evaluates the Influence of Chance on Genetic Data- What are the chances that something else is causing the deviation other than random chance?- Deals with Influence of chance on data- Chance deviation from an expected is diminished by larger sample sizeo Flip a coin 10000 times, it will be more 50/50 than if done only 10 times- Null Hypothesis (When we assume data will fit given ratio)o Assumes there is no real difference between the measured values (ratio) and the predicted values (or ratio) (Basically: No significant difference, and the difference found is attributed to chance)- Chi-square (x2): how well data fit null hypothesiso Further it is from that, less likely it is going to be explained by chanceo With fewer data points, you should be getting close to figure it outo Table 3.3 P value: tells you whether you graduate or not (whether significant or not)o Requires degree of freedom (df) be taken into account, more deviation is expected with a higher degree of freedom (figure 3.11) Degree of freedom: number of possibilities as far as outcomes go df= n-1; n is number of different categories into which each datum point may fall- THIS MEANS: if you have a 16 sided die, then you will have to roll it thousands of times (get more data points) to realistically determine if it weighted Figure 3.11- Fail to reject= yay!- Reject null: bad, - Most of the time, the error you predict is due to random variation- P value tells you whether your error is due to statistical variationVII. 3.9 Pedigrees Reveal Patterns of Inheritance of Human Traits- The lower the number, the easier the study (less times you have to perform experiment)- Pedigrees reveal patterns of inheritance of human traitso Shows family tree with respect to given traito Figure 3.12 (standard conventions)…NEED TO LOOK AT Solid color: affected, carry the mutation Circle: female Square: male Diamond: sex unknown Single horizontal line connecting circle and square: unrelated parents