copyright cmassengale Mendelian Genetics 12/5/2018 Mendelelian Genetics copyright cmassengale

Responsible for the Laws governing Inheritance of Traits Mendelian Genetics 12/5/2018 Gregor Mendel (1822-1884) Responsible for the Laws governing Inheritance of Traits copyright cmassengale

copyright cmassengale Mendelian Genetics 12/5/2018 Gregor Johann Mendel Austrian monk Studied the inheritance of traits in pea plants Developed the laws of inheritance Mendel's work was not recognized until the turn of the 20th century copyright cmassengale

copyright cmassengale Mendelian Genetics 12/5/2018 Gregor Johann Mendel Between 1856 and 1863, Mendel cultivated and tested some 28,000 pea plants He found that the plants' offspring retained traits of the parents Called the “Father of Genetics" copyright cmassengale

Site of Gregor Mendel’s experimental garden in the Czech Republic Mendelian Genetics 12/5/2018 Site of Gregor Mendel’s experimental garden in the Czech Republic Fig. 5.co copyright cmassengale

copyright cmassengale Mendelian Genetics 12/5/2018 Genetic Terminology Trait - any characteristic that can be passed from parent to offspring Heredity - passing of traits from parent to offspring Genetics - study of heredity copyright cmassengale

Particulate Inheritance Mendelian Genetics 12/5/2018 Particulate Inheritance Mendel stated that physical traits are inherited as “particles” Mendel did not know that the “particles” were actually Chromosomes & DNA copyright cmassengale

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copyright cmassengale http://www.youtube.com/watch?v=N5zFOScowqo Traits are created by genes, which are small sections of DNA that code for a protein. Traits result from proteins! Genes are found on chromosomes. Each chromosome can have thousands of genes Sexual organisms have 2 sets ofchromosomes—one set from each parent. copyright cmassengale

copyright cmassengale Mendelian Genetics 12/5/2018 Genotypes Alleles – different forms of a gene (some dominant & some recessive) Homozygous genotype - gene combination involving 2 dominant or 2 recessive alleles (e.g. RR or rr); also called pure  Heterozygous genotype - gene combination of one dominant & one recessive allele    (e.g. Rr); also called hybrid copyright cmassengale

copyright cmassengale Mendelian Genetics 12/5/2018 Designer “Genes” Dominant - stronger of two genes expressed in the hybrid; represented by a capital letter (R) Recessive - gene that shows up less often in a cross; represented by a lowercase letter (r) copyright cmassengale

copyright cmassengale Mendelian Genetics 12/5/2018 More Terminology Genotype - allele combination for a trait (e.g. RR, Rr, rr) Phenotype - the physical feature resulting from a genotype (e.g. red, white) copyright cmassengale

Mendelian Inheritance Each person has 2 copies of every gene—one copy from mom and a second copy from dad. These copies may come in different variations, known as alleles, that express different versions of a trait. For example, 2 alleles in the gene for freckles are inherited from mom and dad: allele from mom = has freckles (F) allele from dad = no freckles (f) child has the inherited gene pair of alleles, Ff (F allele from mom and f allele from dad). Review with students the term “allele” (a variant form of a gene) and help students understand that each gene has a pair or two alleles—one allele from mom and the other from dad.

Mendel’s Laws Law of Segregation- During meiosis, the alleles for each gene separate from each other so that each gamete carries only one allele. Law of Independent Assortment- Genes for different traits are inherited separately (unless located near each other on the same chromosome) Law of Dominance- Some alleles are dominant while others are recessive; the dominant effect will be shown over recessive Review key concepts of Mendelian Inheritance with students. For #3, ask students what situations may call for an unobservable trait to be passed from parents to children. Students may be able to apply their understanding of dominant and recessive traits where parents with both dominant and recessive traits only show dominant traits while being able to pass their recessive traits to the next generation.