Outcomes - Mendelian Inheritance - Outcomes Mendelian...

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Outcomes - Mendelian Inheritance 1. characterisitics of Mendel's work that set him apart as a genetic researcher Mendel’s methods illustrate how rigorous scientific work is conducted: through observation, making hypotheses, and testing the hypotheses with experiments. Most important innovation was his quantitative approach to science, specifically his rigour and statistical analysis. Knew nothing about mutation, meiosis, cells/nuclei Came up with fundamental model of inheritance Careful experimentation with controlled crosses and quantitative analyses 2. components of Mendel's explanatory model Variation in traits due to different alleles/variation in genotype First hypothesis was that the adult plants carry a pair of factors that govern the inheritance of each character Second hypothesis stated that if an- individual’s pair of genes consists of different alleles, one allele is dominant over the other, recessive, allele Third hypothesis Principle of Segregation: Mendel’s principle that the pairs of alleles that control a character segregate as gametes are formed, with half the gametes carrying one allele and the other half carrying the other allele.
1. The genes that govern genetic characters are present in two copies in individuals. 2. If different alleles are present in an individual’s pair of genes, one allele is dominant over the other. 3. The two alleles of a gene segregate and enter gametes singly. Alleles separate randomly into gametes Each organism inherits 2 alleles Phenotype of heterozygote determined by dominant allele 3. distribution of progeny, given parental genotypes in monohybrid and sex-linked crosses Monohybrid cross: cross that involves a single character Punnet square PP x pp: 100% Pp (genotype) Phenotype: 100% dominant phenotype Pp x Pp: 25% PP + 50% Pp +25% pp (genotype) Phenotype: 75% dominant phenotype + 25% recessive phenotype Can calculate number of offspring with each phenotype/genotype
Dihybrid cross: involving two characters 9:3:3:1 Ratio
Sex Linked Genes (Reciprocal cross): inherited differently in males and females. In Mendel’s pea-plants it didn’t matter which parent had which trait, it matters in sex linked traits Sex linked traits are not carried on the Y chromosomes
4. parental genotypes, given distribution of progeny in monohybrid and sex-linked crosses For a cross of Rr x Yy x Rr x Yy , when the gametes fuse randomly, the progeny will show a phenotypic ratio of 9:3:3:1. 5. location of various alleles on homologues Alleles are located at the same spots on the homologous chromosomes, but they are DIFFERENT A locus, the site occupied by a gene on a pair of homologous chromosomes
Two alleles, A and a, of the gene are present at this locus in the homologous pair. These alleles have differences in the DNA sequence of the gene Different alleles located at same locus/spot on homologous chromosomes

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