BIOL 152 1st Edition Lecture 7 Outline of Last Lecture Cell Cycle Outline of Current Lecture Mendelian Genetics Gregor Mendel 1850s Differentiated the blending versus particulate hypotheses of heredity and experimented his own theory through pea plants Worked with garden peas because o Available in many varieties o Easy to manipulate cross pollination o Started experiments with true breeding individuals Genetics Vocabulary Character a heritable feature in an individual Trait a version of a character P F1 F2 generations in experiments Hybrid offspring from two different species of parents Genotype genetic identity of a trait Phenotype physical visible identity of a trait Allele one version of a gene on a chromosome Locus the position of a gene on a chromosome 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 Homozygous having two copies of the same allele Heterozygous having one copy of two different alleles Law of Segregation Alternative version of a gene is called an allele Two alleles are inherited for each character If two alleles differ the dominant one determines the phenotype Two alleles for a heritable character separate during gamete formation Determining genotype from phenotype A testcross crosses an individual with the dominant phenotype with an individual that is homozygous recessive for a trait Purple flowers with white flowers Use test cross when phenotype id given but not genotype A dihybrid cross follows 2 traits in offspring o Uses two parents that are true breeding for the traits Law of Independent Assortment Each pair of alleles segregates independently of other alleles during gamete formation Only applies to genes located on different chromosomes Genes located near each other on the same chromosome tend to be inherited together Law of Segregation Two alleles for 1 character separate Law of Independent Assortment Pair of alleles from two different characters separate Probability of Genetic Events Multiplication this rule applies for two events occurring together but are independent of each other Probability of sperm having maternal allele Addition for two mutually exclusive events Probability of F2 heterozygote Extending Mendelian Genetics Complete Dominance the homozygous dominant and heterozygous have identical phenotypes Incomplete Dominance the heterozygous genotype has phenotype somewhere between the homozygous phenotypes Codominance each allele contributes to overall phenotype of heterozygous genotype Pleiotropy when a single gene can affect multiple phenotypes Recessive diseases Cystic Fibrosis Sickle Cell disease Epistasis a gene at one locus can alter the phenotype of a gene at a second locus Polygenic Inheritance multiple genes that contribute to one phenotype Quantitative continuous characteristics Environmental Influences Nature versus Nurture idea of how the environment affects your phenotype and ways society and family raises you as an individual The phenotype of some genes can be affected by environmental factors Current Lecture Speciation
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