Mendelian Inheritance PDF

Mendelian Inheritance Johann Gregor Mendel (1822-1884) FATHER OF GENETICS Discovered the fundamental laws of inheritance. ○ Genes come in pairs ○ Genes are inherited as distinct units ○ Segregation of parental genes ○ Dominant or recessive traits.  MENDEL’S LAWS OF HEREDITY 01...

Mendelian Inheritance Johann Gregor Mendel (1822-1884) FATHER OF GENETICS Discovered the fundamental laws of inheritance. ○ Genes come in pairs ○ Genes are inherited as distinct units ○ Segregation of parental genes ○ Dominant or recessive traits.  MENDEL’S LAWS OF HEREDITY 01 02 03 Law of Law of Law of SEGREGATION INDEPENDENT DOMINANCE ASSORTMENT Law of Segregation Each inherited trait is defined by a gene pair. Each sex cell contains only one gene of the pair. Offspring inherit one genetic allele from each parent. Law of Independent Assortment Genes for different traits are sorted separately from one another so that the inheritance of one trait is not dependent on the inheritance of another. Law of Dominance An organism with different alleles of a gene will express the form that is dominant.  DOMINANT & RECESSIVE OBSERVE & DISCUSS What do you notice about the parent and offspring plants below?  DOMINANT vs RECESSIVE THINK ABOUT IT: How do the offspring of these parents support Mendel’s Law of Dominance?  DOMINANT vs RECESSIVE Dominant = trait that always shows up in the next generation. Dominant traits only need one allele present to be expressed  DOMINANT vs RECESSIVE Recessive = trait that can hide in the offspring. Recessive traits require two copies of the allele to be expressed.  DOMINANT vs RECESSIVE THINK ABOUT IT: Which trait is dominant: tall or dwarf? How do you know?  DOMINANT vs RECESSIVE TT Homozygous = tt two identical Tall alleles for the Dwarf gene  DOMINANT vs RECESSIVE TT These are also referred to as “true breeding” or tt pure-breed. Tall Can you think of a Dwarf reason why they’re called this?  DOMINANT vs RECESSIVE THINK ABOUT IT: Can the offspring TT tt of these parents be homozygous? How do you know?  DOMINANT vs RECESSIVE Heterozygous = two different alleles for TT tt the gene Dominant trait expressed & recessive trait hidden! Tt  DOMINANT vs RECESSIVE These are also referred to as TT tt “hybrid”. Can you think of a reason why they’re called this? Tt  GENOTYPE vs PHENOTYPE TT tt Dwarf TT Tt tt Tall Tt  GENOTYPE vs PHENOTYPE Genotype = genes What do you notice about the how it’s written “dwarf” genotype? TT Tt tt Tall Dwarf What do you notice about the Phenotype = trait two “Tall” genotypes? how it looks  GENOTYPE vs PHENOTYPE Which phenotype is dominant? TT Tt tt Tall Dwarf Why?