* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Download Exploring Mendelian Genetics
Public health genomics wikipedia , lookup
Pharmacogenomics wikipedia , lookup
Gene expression programming wikipedia , lookup
Genetic drift wikipedia , lookup
Genetically modified crops wikipedia , lookup
Polycomb Group Proteins and Cancer wikipedia , lookup
Transgenerational epigenetic inheritance wikipedia , lookup
Pathogenomics wikipedia , lookup
Population genetics wikipedia , lookup
Nutriepigenomics wikipedia , lookup
Artificial gene synthesis wikipedia , lookup
Hardy–Weinberg principle wikipedia , lookup
Heritability of IQ wikipedia , lookup
Essential gene wikipedia , lookup
Genome evolution wikipedia , lookup
Behavioural genetics wikipedia , lookup
Genome (book) wikipedia , lookup
History of genetic engineering wikipedia , lookup
Ridge (biology) wikipedia , lookup
Genomic imprinting wikipedia , lookup
Gene expression profiling wikipedia , lookup
Epigenetics of human development wikipedia , lookup
Designer baby wikipedia , lookup
Minimal genome wikipedia , lookup
Microevolution wikipedia , lookup
Biology and consumer behaviour wikipedia , lookup
Sex-limited genes wikipedia , lookup
Exploring Mendelian Genetics 11-3 Independent Assortment Mendel wondered if the segregation of one pair of alleles affect the segregation of another pair of alleles To find the answer, Mendel did an experiment to follow two different genes as they passed from one generation to the next Two-Factor Cross Mendel crossed true-breeding plants that produced only round yellow peas with a plant that produced wrinkled green peas All of the F1 offspring were round and yellow – Proving round and yellow are dominant While the cross didn’t prove if segregation happened, it provided the hybrid plants needed for the F2 generation To get the F2 generation, Mendel crossed two of the F1 offspring – RrYy x RrYy 556 seeds were produced, with 4 different characteristics 315 seeds were yellow and round – 32 were green and wrinkled – Dominant traits Recessive traits 209 had a combination of traits – ~1/2 were green and round – ~1/2 were yellow and wrinkled Recessive and dominant Dominant and recessive Phenotype ratio 9:3:3:1 Mendel discovered the principle of independent assortment – Genes for different traits can segregate independently during the formation of gametes – Accounts for many genetic variations among organisms Summary of Mendel’s Principles Inheritance of biological characteristics is determined by genes. Genes are passed from parents to their offspring When there are 2 or more alleles, some forms are dominant and others recessive In sexually reproducing organisms, each adult has 2 copies of each gene – genes are segregated when gametes form Alleles for different genes usually segregate independently of one another Beyond Dominant and Recessive Alleles Despite the importance of Mendel’s work, there are exceptions – Some alleles are neither dominant or recessive – Some traits are controlled by multiple alleles or multiple genes Incomplete Dominance One allele is not completely dominant over another allele Heterozygous individual is a blend of the two homozygous phenotypes Ex: red (RR) x white (WW) = pink (RW) Codominance In heterozygous individuals, both traits appear at the same time They are not blended together like in incomplete dominance Ex: heterozygous chickens that have erminette coloration (black and white feathers) Multiple Alleles Genes that more than two alleles are said to have multiple alleles Individuals still only have 2 copies of a gene, but there is variation in the alleles they can inherit Ex: rabbit fur and blood types Polygenic Traits Traits controlled by two or more genes Show a wide range of phenotypes Ex: human skin color and eye color Applying Mendel’s Principles Thomas Hunt Morgan wanted to test Mendel’s principles on organisms other than plants He needed an animal that produced large numbers of offspring, in a short amount of time Used Drosophila melanogaster – common fruit fly Soon, other biologists tested all of Mendel’s principles on a variety of organisms and discovered that the principles applied to them as well Genetics and the Environment Characteristics of any organism are not based only on the genes they inherit Also based on the interaction of their genes with the environment Genes provide a plan for development, but how that plan unfolds also depends on the environment