GEN 3022 1st Edition Lecture 2 Outline of Last Lecture I Overview of Genetics a Molecular Expression b The study of genetics II Overview of DNA a Basics of DNA and RNA b Transcription and Translation c DNA Technologies III Gene Insertion IV Traits a Environmental Influence on Trait Expression Trait expression at different biological levels Outline of Current Lecture I Introduction II Vocabulary III Mendel and the Pea Plant Experiments a Advantages of using the garden pea b Seven Characters of Inheritance in Peas c Experimental Set up IV Conclusions of the Experiments 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 a Patterns of inheritance b Mendel s Law of Segregation c Mendel s Law of Independent Assortment d Recessive vs Dominant V Punnett Squares Current Lecture I II III Introduction a There were many hypotheses on how inheritance works b Many thought that inheritance involved the blending of traits from the parents to the offspring c Gregor Mendel used pea plant experiments to study the patterns of inheritance and came upon some ground breaking discoveries Vocabulary a Hybridization mating or crossing of two individuals with different characteristics ex purple flowered plant and white flowered plant b Hybrids resulting offspring of the aforementioned cross c Mendelian factors current term is genes d Allele different versions of a trait on the same gene ex allele for blue eyes and allele for green eyes an individual can have two of the same or one of each e Homozygous an individual with two of the same alleles for a trait two alleles for green eyes f Heterozygous an individual with two different alleles for the same trait g Genotype how an individual s traits appear genetically not physically looking at the alleles only h Phenotype how an individual s traits appear physically an individual s outward appearance i Character the morpohological characteristics of an organism ex eye color j Trait the specific properties of a character ex blue eyes k True breeder a homozygous individual that produces the same trait over several generations Mendel and his pea plant experiments a Advantages to using the garden pea i peas have both male and female reproductive organs making it easy to manually cross breed plants or self fertilize ii peas have many unique traits that are easy to observe IV V b 7 distinguishable traits that could be used to observe patterns of inheritance height flower color flower position seed color seed shape pod color and pod shape i At first Mendel began with a single trait cross monohybrid cross where he only bred for one character ii Later he began experimenting with two trait dihybrid crosses involving multiple characters c Experimental Set Up Mendel used two types of fertilization to cross plants He then observed how the characteristics of the parent plant s appeared in the offspring to figure out the pattern of inheritance i Two types of fertilization 1 Cross breeding mating two different plants to each other by manually moving the pollen of one plant to the anther of another 2 Self fertilization mating a plant to itself by pollinating its own anther ii Mendel recorded the phenotypes and genotypes of the parent plants and those of the offspring to observe how traits were inherited Experimental Conclusions a The results of Mendel s thousands of plant crosses refuted the previous hypotheses for patterns of inheritance blending mechanisms b Mendel s Law of Segregation each parent plant has two alleles for a given character and can be homozygous or heterozygous During gamete formation egg and sperm the alleles segregate randomly so that half of the gametes receive one factor and half receive the other c Mendel s Law of Independent Assortment during gamete formation the segregation of any pair of hereditary determinants is independent of the segregation of other pairs similar to the Law of Segregation d Dominant and Recessive Traits One type of allele is dominant and the other is recessive meaning that if an individual is heterozygous or homozygous for the dominant allele then the individual will exhibit the dominant trait Punnett Squares a Punnett squares are a way of predicting what genotypes will appear in the offspring for a monohybrid or dihybrid cross this method uses the genotypes of the parents b In a dihybrid cross with heterozygous parents ex TtRr X TtRr the ratio of phenotypes of the offspring is always 9 3 3 1 dominant dominant dominantrecessive recessive dominant recessive recessive c From a dihybrid cross of heterozygous parents there are combinations of traits that appear in the offspring that were not seen in the parents