BIOL 3315 1st Edition Lecture 2 Outline of Last Lecture I. Historical summaryII. Genetic is the science of heredityIII. EvolutionOutline of Current Lecture IV. Genetics and the OrganismV. GeneticsVI. Physical and Chemical basisVII. From gene to transcriptVIII. Genetic variationIX. Continuous variationX. Discontinuous variationXI. Classical Genetic methodologyXII. Genes, environment, organismCurrent LectureIV. Genetics and the Organism A. Hereditary material is DNA, a double helix of complementary polynucleotides.B. Genes are segments of DNA encoding a transcript.C. Hereditary variation is caused by variant forms of genes known as alleles.D. Alleles can be studied at many levels.E. Each species has its own distinctive pool of genes.F. Evolution is a consequence of genetic changes in a population over timeV. GeneticsA. Experimental science of heredityB. Grew out of need of plant and animal breeders for greater understanding of inheritance of economically important characters.C. Gregor Mendel: discovered principles of heredityD. Today, genes are explained in molecular termsVI. Physical and chemical basisA. Genome: basic component of DNA of an organism1. Haploid: one copy of genome (fungi, algae, bacteria)2. Diploid: two copies of genome (plants, animals) B. Genes: regions of chromosomal DNA encoding transcriptsThese 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.1. Different genes on each chromosome2. Homologs: chromosomes with same genes3. In diploids, one homolog inherited from each parentC. DNA: complementary polynucleotide chains1. A-T and G-C base pairs2. Double helixVII. From gene to transcriptA. DNA non coding RNA: RNA genes1. rRNA2. tRNA3. snRNAs4. microRNASB. DNA mRNA polypeptide: protein-coding genes1. DNA mRNA: transcription2. mRNA polypeptide: translationa. Genetic codeb. Ribosomesc. tRNAVIII. Genetic variation A. Alleles1. Alternative forms of gene encoding proteins or RNAs with altered amino acid/ RNA sequence 2. Located at the same position (locus) on chromosomeB. Phenotype: appearance or physiological expression of geneC. Genotype: alleles present in individualD. Discontinuous variation (qualitative)E. Continuous variation (quantitative) IX. Continuous variation A. Unbroken range of phenotypes; no discrete classesB. Intermediate phenotypes more common than extreme onesC. A result of a combination of genetic and environment variationD. Underlying genetic basis often difficult to studyE. Important in plant and animal breeding X. Discontinuous variationA. Relatively rare compared to continuous variationB. Variation falls into distinct categoriesC. Usually due to differences between alleles1. Designated by letters, e.g. A and a2. A dominant to aD. Polymorphism: multiple alleles of single geneE. Mutants: rare, exceptional variant1. Normal phenotype called wild-typeF. Alleles arise through mutation, DNA changeXI. Classical Genetic methodologyA. Isolation of mutation (natural or induced)B. Analysis of progeny of controlled mating (crosses)C. Biochemical analysis of underlying cellular processesD. Microscopic analysis of chromosomes (cytogenetic) and phenotypesE. Direct analysis of DNA1. Genomics: sequencing genes or entire genome2. Bioinformatics: extraction of information from DNAXII. Genes, environment, organismA. Model 1: genetic determination1. Characters specified by genesB. Model 2: environmental determination1. Characters determined by environmentC. Model 3: Genotype-environment interaction1. Gene expression is conditioned by environmentD. Norm of reaction: set of environment-genotype relations for given genotype1. Single genotype may have several phenotypes, depending upon the environmentE. Developmental noise: random events in development leading to phenotypic variation F. Darwin recognized role of hereditary variation in evolution (but was unaware of true mechanism of heredity)G. Genetic variation (product of mutation) is raw material for evolutionary changeH. Evolution can happen two different ways:1. Natural selection: differential reproduction of individuals with different alleles2. Random genetic drift: change in frequencies of genetic variants resulting from random, non-selective