BIOL 1441 1st Edition Lecture 24 Outline of Last Lecture I. Gregor MendelII. Theories of inheritanceIII. GenesIV. Mendel’s laws of inheritanceV. Law of segregationVI. Punnett squareVII. Test CrossesVIII. Law of independent assortmentOutline of Current Lecture I. The Laws of ProbabilityII. The Multiplication RuleIII. Extending Mendelian genetics for a single geneIV. The Spectrum of DominanceV. Multiple AllelesVI. PleiotropyCurrent LectureI. The Laws of Probabilitya. Probability ranges from 0 to 1i. Event certain to occur 1 (100%)ii. Event certain not to occur is 0 (0%)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.b. Event- any collection of outcomes of an experimentc. Independent events: outcomes that do not effect each otheri. Ex. Coin tossii. Coin toss- outcome of one toss has no impact on the outcome of the nexttoss (independent events)iii. Probability of tossing heads ½ and tails ½ iv. 1 out of 2 choicesd. Probabilityi. All possible outcome must equal 1ii. What is the chance of picking ace of spades out of a deck of cards?1. 1/52iii. What is the chance of picking any other card except the ace of spades out of the deck?1. 51/52II. Multiplication Rule (two independent events occurring)a. Chance that 2 coins flipped up in the air will both land on heads?b. Multiply the probability of one event (one coin landing on heads) times the probability of the second event (the other coin landing on heads)c. ½ x ½ = ¼ 25% chance that both coins will land on headsd. The probability that two or more independent events will occur together is the product of their individual probabilitiese. Probability in an F1 monohybrid cross can be determined using the multiplication rule (Pp x Pp)f. Like flipping a coin: each gamete has a 1/2 chance of carrying the dominant alleleand a 1/2 chance of carrying the recessive alleleg. Solving Complex Genetics Problemsi. Apply multiplication & addition rules to predict the outcome of crosses involving multiple traitsii. Dihybrid cross is equivalent to two independent monohybrid crosses occurring simultaneouslyiii. To calculate the chances for various genotypes, each trait is considered separately, and then the individual probabilities are multiplied togetherIII. Extending Mendelian Genetics for a Single Genea. Inheritance of characters by a single gene may deviate from simple Mendelian patterns in the following situations:i. 1. When alleles are not completely dominant or recessiveii. 2. When a gene has more than two allelesiii. 3. When a gene produces multiple phenotypesIV. The Spectrum of Dominance a. Alleles can show varying degrees of dominance and recessiveness in relation to each otherb. Mendel’s traits- Complete Dominance, occurs when phenotypes of the heterozygote and dominant homozygote are identical (PP or Pp: purple flower)c. Codominance- two dominant alleles affect the phenotype in separate, distinguishable waysi. Both are expressed distinctly flowers with splotches of two colorsii. Blood types- A, B, Oiii. Types A & B codominant, O recessive (ii)iv. AA or Ai- type Av. BB or Bi- type Bvi. ii- Type Ovii. AB- both A and B one does not affect the expression of the otherd. Incomplete dominance- phenotype of F1 hybrids is somewhere between the phenotypes of the two parental varietiesi. Creates a whole new phenotype- blending of allelese. Relation Between Dominance & Phenotypei. A dominant allele does not subdue a recessive allele; alleles don’t interactii. Alleles- different forms of a gene, both are expressed1. Variations in a gene’s nucleotide sequenceiii. Recessive allele is expressed but the phenotype is masked or hidden by dominant phenotypef. Frequency of Dominant Allelesi. Dominant alleles are not necessarily more common in populations than recessive alleles.ii. Polydactyly- born with extra fingers or toes, dominant1. 1 baby out of 400 in US is born with extra fingers or toes2. More common trait of five digits- recessiveiii. Recessive allele is far more prevalent than the dominant allele in the populationV. Multiple Allelesa. Most genes exist in more than two allelic formsb. ABO blood group- 3 alleles for the enzyme (I) that attaches A or B carbohydrates to RBCs: IA, IB, iVI. Pleiotropy- one gene, many effectsa. Pleiotropy- gene that controls several functions or has multiple phenotypic effectsb. Pleiotropic alleles- responsible for the multiple symptoms of certain hereditary diseasesi. Cystic fibrosis & sickle-cell diseasec. Difficult to trace through families- different symptoms appear as different