BIOL 152 1st Edition Lecture 7Outline of Last Lecture - Cell Cycle Outline of Current Lecture Mendelian GeneticsGregor 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 varietieso Easy to manipulate (cross pollination)o Started experiments with true breeding individualsGenetics VocabularyCharacter - a heritable feature in an individual Trait - a version of a characterP, F1, F2 - generations in experimentsHybrid - offspring from two different species of parentsGenotype - genetic identity of a traitPhenotype - physical, visible identity of a traitAllele - one version of a gene on a chromosomeLocus - the position of a gene on a chromosomeThese 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 alleleHeterozygous - having one copy of two different allelesLaw of SegregationAlternative version of a gene is called an alleleTwo alleles are inherited for each characterIf two alleles differ, the dominant one determines the phenotypeTwo alleles for a heritable character separate during gamete formationDetermining 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 offspringo Uses two parents that are true-breeding for the traitsLaw 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 togetherLaw of Segregation- Two alleles for 1 character separate - Law of Independent Assortment- Pair of alleles from two different characters separate Probability of Genetic EventsMultiplication - this rule applies for two events occurring together, but are independent of each other- Probability of sperm having maternal alleleAddition - for two mutually exclusive events- Probability of F2 heterozygoteExtending Mendelian GeneticsComplete Dominance - the homozygous dominant and heterozygous have identical phenotypes Incomplete Dominance - the heterozygous genotype has phenotype somewhere between the homozygous phenotypesCodominance - each allele contributes to overall phenotype of heterozygous genotypePleiotropy - when a single gene can affect multiple phenotypesRecessive diseases - Cystic Fibrosis / Sickle Cell disease Epistasis - a gene at one locus can alter the phenotype of a gene at a second locusPolygenic Inheritance – multiple genes that contribute to one phenotype- Quantitative continuous characteristics Environmental InfluencesNature 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 factorsCurrent Lecture-
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