BIOL 3451 1st Edition Lecture 3Outline of Last Lecture 2.1 Cell Structure and genetic function2.2 Chromosomes Exist in Homologous pairs in Diploid Organisms2.3 Mitosis2.4 Meiosis2.5 The development of gametes2.6 Sexual reproduction in Diploid organismsOutline of Current Lecture 3.1 Mendel Used a Model Experimental Approach to Study Patterns of Inheritance3.2 The Monohybrid Cross 3.3 Mendel’s Dihybrid Cross Generated a Unique F2 Ratio3.4 The Trihydrid Cross3.5 Mendel’s Work Was Rediscovered in the Early 20th Century3.6 Independent Assortment Leads to Extensive Genetic Variations.3.7 Laws of Probability3.8 Chi-square Analysis3.9 Pedigrees Reveal Patterns of Inheritance of Human Traits.Current Lecture3.1 Mendel Used a Model Experimental Approach to Study Patterns of Inheritance 1856: Mendel performed his first set of hybridization experiment using thegarden pea. Garden pea: easy to grow andhybridize artificially. Mating can becontrolled since garden peas haveboth male and female.These 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. Mendel used 7 visible features, each had 2 contrasting traits. Mendel didn’t do anything new. Except the math part of it.3.2 The Monohybrid Cross  Consist of 1 pair of contrasting traits. Made by mating true-breeding individuals from 2 parents strains (Each exhibits 1 of the 2 character under study). Selfing: self-fertilization of individuals from this first generation P (parental) generation; F1 (first filial) generation; F2 (second filial) generation If tall or draft pea self-fertilize, they will breed true, which produce there respective traits for future generations. Tall plant cross with a draft plant = F1 generation of only tall plants; 3:1 (Tall:draft) ratio Reciprocal crosses: Monohybrid crosses were not sex-dependent. Medel’s 3 postulates:1) Genetic characters are controlled by unit factorsexisting in pairs in individual organisms. 2) When 2 unlike unit factors responsible for a singlecharacter are present in a single indicidual, one unitfactor is dominant to the other, which is said to berecessive. 3) During the formation of gametes, the paired unitfactors separate, or segregate, randomly so that eachgamete receives one or the other with equallikelihood. We got the Law of Segregation from the monohybridcross. Phenotype: Physical expression of a trait.QuickTime™ et undécompresseur sont requis pour visionner cette image. Genotype: genetic makeup of an individual for the trait or traits describes. Homozygous: when both alleles are the same (DD or dd) Heterozygous: when the alleles are different (Dd) Tall factor (allele) is DOMINANT Punett square: predict the new generation by entering themale and female gametic information into each box andknow about all the possible genotype outcome F1 X F1 Monohybride Cross NOTE that First generation has an outcome of a 3:1 ratiowhile the second generation has a 1:2:1 ratio!  TestCross: The organism expressing the dominant phenotype buthaving an UNKNOWN genotype is crossed with a know homozygous recessive individual.3.3 Mendel’s Dihybrid Cross Generated a Unique F2 Ratio Dihybrid cross: involving 2pairs of contrasting traits. Those characteristics areinherited independently. Theydon’t come together; this iswhy the outcome is out of 16.If the characteristic would beinherited together, theoutcome of the possibilitywould be out of 4. Product law of probabilities: When 2 independent events occur simultaneously; the probability of the 2 outcomes occurring in combination is equal to the product of their individual probabilities of occurrence. Mendel’s 4th postulate: During gamete formation, segregation pairs of unit factors assort independently of each other. Mendel’s Dihybride ratio: 9:3:3:13.4 The Trihydrid Cross Three pairs of contrasting traits. The forked-line (branches diagram) method: Today, the forked-line method is not really used anymore since computers do the calculation instead. However, we still need to understand the significance of the results.3.5 Mendel’s Work Was Rediscovered in the Early 20th Century Continuous variation: offspring were ablend of their parent’s phenotype. Discontinuous variation: Variation dueto a dominant-recessive relationshipbetween discrete or particulate units. Flemmings: discovery of chromosomesin the nuclei of salamander cells. Sutton & Boveri are credited withinitiating the chromosomal theory ofinheritance: The genetic material inliving organisms is contained inchromosomes. Law of independent assortment withchromosomes:-------------------------3.6 Independent Assortment Leads toExtensive Genetic Variations. Genetic variation occur because the 2members of any homologous pair of chromosomes are rarely, if ever, genetically identical. Number of possible gametes = 2n ,where n= the haploid number of chromosomes Human= 223 ,so 8x106 possible gametes from each parents.3.7 Laws of Probability Probability range from 0.0 (no chance to occur) to 1.0 (certain to occur) Product law: the probability of 2 or more events occurring simultaneously is equal to theproduct of their individual probabilities. Sum law: the probability of the possible outcomes of 2 events are independent of one another but can be accomplish in more than one way. Binomial theorem: used to analyse cases where there are alternative ways to achieve a combination of events.3.8 Chi-square Analysis No need to know for the exam, just need to know what it is used for. This test take into account the observed deviation in each component of a ratio (from what was expected) as well as the sample size and reduces them to a single numerical value.  Degree of freedom (df): equal to n-1. Where n is the number of possible outcome ex: if there is a 3:1 ratio, n=2, so the df=13.9 Pedigrees Reveal Patterns of Inheritance of Human Traits. Pedigree: family tree indicating the presence or absence of the trait in question for each member of each generation. Consanguineous: parents are related. Monozygotic: identical twins Dizygotic: Fraternal twins Albinism: autosomal recessive inheritance. Huntington disease: autosomal dominant