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UM BIOB 272 - Mendelian Genetics

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BIOB 272 1st Edition Lecture 5Outline of Last Lecture I. DNA (deoxyribonucleic acid) II. Central DogmaIII. Genome1. 1st Genome Records2. Human Genome OrganizationA. Human extensive splicing complexity in humansB. Genome made of two types of DNA1. Euchromatic: 2. Heterochromatic DNAIV. Evolutionary GenomicsTimeline of Genomics KnowledgeOutline of Current Lecture Mendelian Genetics (Transmission Genetics)I. Mendelian Genetics:II. GregorMedel’s (“father of genetics”) Contributions:i. 3 PrinciplesIII. Why garden Peas (Pisum)?-the right organismVI. Experimental Approach1. Self-fertilized plants 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.2. Crossed two different true-breeding lines3. Self-fertilized an F1 hybrid- Example: Tall (TT)=dominant, Dwarf (Tt)= recessiveIV. Mendel’s Principles1. Dominance2. SegregationV. Mendels’ reasoning in modern termsCurrent LectureMendelian Genetics (Transmission Genetics)I. Mendelian Genetics:a. Science is a process, not a collection of infob. We study his work because of his processII. GregorMedel’s (“father of genetics”) Contributions:i. Particulate nature of inheritance (gene)ii. 3 Principles1. Dominance (alleles)2. Segregation (alleles passed with equal frequency)3. Independent Assortment (different trait assorted independently)iii. He asked the right questioniv. Used the right organism-peas (used mice first, though)v. Had the right scientific process: observation, hypothesis, experiment, quantitative analysis, hypothesis testing…repeat.III. Why garden Peas (Pisum)?-the right organismi. Many seeds per cross=large sample sizesii. Short-generation timeiii. Easy to self-fertilize and cross-fertilizeiv. Discrete traits: flower color, flower position, seed color, pod shape, pod color, seed shape, etc.IV. Experimental Approach:1. Self-fertilized plants to generate ‘true-breeding’lines for each trait => parental generation (P)2. Crossed two different true-breeding lines=> 1st generation progeny (F1 hybrids)3. Self-fertilized an F1 hybrid=> 2nd generation progeny (F2 hybrids)- Example: Tall (TT)=dominant, Dwarf (Tt)= recessiveo 1st generation: only one phenotype. no blending= 100% TT (tall)o 2nd generation: Recessive type stillpresent, hasn’t been“blended” away some variation= 75% tall, 25% dwarf (TT + 2 Tt )+ tt = 3:1 ratioV. Mendel’s Principles:1. Dominance: In a heterozygote, one allelemay conceal another.2. Segregation: In a heterozygote, twodifferent alleles segregate from each otherwithequal probability during the formation of gametesExample:In whippets, the “bully” trait is caused by a mostlyrecessive allele (m) at a single gene.You cross a“bully” female with a heterozygous male. What proportion of the resulting offspring wouldyou expect to be bullies?Answer: Use can use a Punnett square to find answer and you get Mm,mm,mM,mm …mm is bully and Mm is heterozygous male so… 2/4= 50% are bullies VI. Mendels’ reasoning in modern terms1. Each parent carries 2 “factors” (alleles) for a trait2. The two alleles can be identical or different(true-breeding parents have 2 identical alleles and aretermed homozygous)3. When 2 alleles are different (individual is heterozygous) ,one may dominant (determines the trait) and the otherrecessive (hidden)4. Alleles segregate equally (50:50) and gametes fuse atrandom during fertilization => Mendel’s law


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