Mendel & Gene Idea Notes PDF
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These notes summarize Mendel's work on genetics, including his laws of inheritance, concepts of dominant and recessive traits, and various types of inheritance like incomplete dominance, codominance, multiple alleles, and epistasis. The notes discuss how environmental factors affect gene expression.
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# Ch 14 Mendel & Gene Idea ## 14.1 - Mendel used scientific method to identify 2 laws of inheritance - He used peas. - Features heritable (passed on) -> Character -> Variations in - True-breeding: plants that produce offspring character trait w/ the same traits - P<sub>3</sub>: pu...
# Ch 14 Mendel & Gene Idea ## 14.1 - Mendel used scientific method to identify 2 laws of inheritance - He used peas. - Features heritable (passed on) -> Character -> Variations in - True-breeding: plants that produce offspring character trait w/ the same traits - P<sub>3</sub>: pure-bred parental generation - F<sub>1</sub>: offspring of parents - F<sub>2</sub>: offspring of F<sub>1</sub> ## Dominant and Recessive Traits - Dominant trait: hides recessive trait - Recessive trait: trait hidden by dominant trait - *Know what a gene is* - Alleles: DNA, alternative versions of a gene - *Mendel's Concepts* 1) alternative versions of genes account for variation in inherited characteristics. - Alleles for flower color 2) for each character/trait an organism inherits 2 alleles. One from each parent. 3) If the 2 alleles at a locus differ: then one is dominant and determines the organism's appearance - The other is a recessive allele 4) Law of segregation: 2 alleles form a heritable characteristic separate/segregate during gamete formation and end up in different gametes - Phenotype: what it looks like - Genotype: Genetic makeup - homozygous: recessive pp - homozygous: dominant PP - heterozygous: Pr - *Memorize Fig 14.6* - **Test cross:** crosses where we try to determine genotype - **Law of Independent Assortment** - **Monohybrid:** heterozygous for 1 characteristic - **Dihybrid**: heterozygous for 2 characteristics - Each pair of alleles segregates independently of any other pair of alleles during gamete formation. ## 14.2 Probability Laws Govern Mendel's Concepts. - Multiplication states that the probability that 2 or more independent events occur together is the product of their individual probabilities. - Addition: the probability of any 1 of 2 or more mutually exclusive events will occur is calculated by adding together their individual probabilities. - These rules are applied to monohybrid crosses. - **14.3 More Complex Patterns of Inheritance Than Mendelian Genetics** - Genes deviate from Mendelian genetics. - Alleles not completely dominant or recessive - Gene has more than 2 alleles - Gene produces multiple phenotypes - **Degrees of Dominance** - **Complete dominance:** occurs when phenotypes of the heterozygote & dominant homozygote are identical - Example: complete dominance: F<sub>1</sub> hybrid is identical to the dominant parent - **Incomplete dominance:** F<sub>1</sub> hybrids is somewhere between the phenotypes of the parental varieties. - **Codominance:** 2 dominant alleles affect the phenotype in separate distinguishable ways. - **Multiple Alleles:** most genes exist in populations in more than 2 allelic forms (ex 4 phenotypes of ABO blood types) - **Pleiotrophy:** Most genes have multiple phenotypic effects (ex sickle cell disease. - **2 or more genes** - **Epistasis:** expression of a gene at one locus alters the phenotypic expression of a gene at a second locus. - **Polygenic Inheritance:** 2 or more genes impact phenotype. - **Environmental Impacts on Phenotype** - **14.4 Many human traits follow Mendelian patterns.** - **Inheritance:** - **Pedigree Analysis:** family tree that describes the inheritance of genetic traits across generations. - **Genetic Testing & Counseling** - **Multifactorial Disorders:** genetic & environmental components - Lifestyle has a tremendous effect on phenotype
