Gregor Johann Mendel “Father of Genetics” Mendelian Genetics 12/7/2018 Gregor Johann Mendel “Father of Genetics” Austrian monk, mathematician by trade 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 Between 1856 and 1863, Mendel cultivated and tested some 28,000 pea plants He found that the plants' offspring retained traits of the parents

Mendelian Genetics 12/7/2018 Genetic Terminology Trait - any characteristic that can be passed from parent to offspring by genes(code on DNA) and their alleles(specific protein sequences) Heredity - passing of traits from parent to offspring Genetics - study of heredity

Mendel’s Experimental Methods Mendelian Genetics 12/7/2018 Mendel’s Experimental Methods Mendel hand-pollinated flowers using a paintbrush He snipped the stamens to prevent self-pollination Covered each flower with a cloth bag He traced 7 traits through the several generations Ultimately he produced pure strains for each

Seven Pea Plant Traits GENE ALLELES GENE ALLELES Mendelian Genetics 12/7/2018 Seven Pea Plant Traits GENE ALLELES GENE ALLELES

Mendel’s Flowers Mendel’s questions: If traits are known, can the inheritance of the traits in offspring be predicted? What is the ‘mechanism’ for inheritance? With his pure strains Mendel began systematically crossing plants, observing one trait at a time: Monohybrid Crosses = 1 gene and its 2 alleles He let the plants self-pollinate during these experiments He observed the offspring produced for each trait, in each generation, for any patterns that appeared.

First filial generation of offspring PURE STRAINS WHY no white? What happened to the white trait? First filial generation of offspring Second filial generation White trait reappeared in this generation, so there must be some ‘factor’ in the purple flower that masked it

Mendelian Genetics 12/7/2018 Mendel’s Flowers

Mendelian Genetics 12/7/2018 Mendel’s Conclusions The trait that is expressed if present he called dominant; represented by a capital letter (R) Recessive – trait that is expresses only if the dominant is not present; represented by a lowercase letter (r) Factors: sequence of DNA that codes for a trait, today we know those are the GENES Alleles –variant(protein code) of a gene (dominant and/or recessive) Ex: Trait(Gene)=Flower Color Alleles=Purple/White Regardless of the trait, results were the same and could be predicted in future generations…Mendel developed his first law of genetics; The Law of Dominance Gene Flower Color Maternal Chromosome Paternal Chromosome

100% of the F1 offspring will express only the “dominant” trait. Mendelian Genetics 12/7/2018 Law of Dominance In a cross of parents(P) that are pure for contrasting traits: only one form of the trait will appear in the F1 100% of the F1 offspring will express only the “dominant” trait.

Let’s see how the Law of Dominance works, by adding the allele notations… RR rr Rr Rr x Rr Rr rr RR Rr

Let’s Practice! Using a yellow and a green colored pencil fill in the circles representing pea seed color. Then fill in the allele notations. YELLOW(R) is dominant GREEN(r) is recessive   RR rr rr Rr Rr RR Rr Rr rr

GENOTYPEs Possible allele combinations for a trait Mendelian Genetics 12/7/2018 GENOTYPEs Possible allele combinations for a trait Homozygous – allele combination involving two of the same alleles; can be either Homozygous dominant: RR Homozygous recessive: rr Heterozygous – allele combination of one dominant & one recessive allele  Heterozygous: Rr

PHENOTYPE the physical features resulting from the genotype; am I… Phenotype also refers to your chemical features as well; enzymes and functional proteins, like hemoglobin, are also determined by genes and allele combinations PURPLE or, am I WHITE

MONOHYBRID CROSSES PUNNETT SQUARES

Mendelian Genetics 12/7/2018 Punnett Squares Diagram that is used to predict an outcome of a particular cross or breeding experiment Illustrate Mendel’s Second Law of Genetics: Law of Segregation

RR rr Rr RR Rr rr RR Rr Rr rr 1 2 3 4 5 6 Homozygous Dominant Parents Recessive Parents 2 HDP X HRP P1 3 R R r r R R RR rr Rr R r r R r r G: 4:4 Ph: 4:4 G: 4:4 Ph: 4:4 G: 4:4 Ph: 4:4 Heterozygous Parents F2 4 5 HDP X Hetero 6 HRP X Hetero R r R R r r RR Rr rr RR Rr Rr rr R R R r r r G: 1:2:1 Ph: 3:1 G: 2:4 Ph: 4:4 G: 2:4 Ph: 2:4

EYES ee Ee 50 E e e Ee ee e Ee ee BLUE Ee KERMIT EYES BLACK ee NOSE 1. TOSS A COIN TO DETERMINE DOMINANT ALLELE FOR EACH TRAIT. 2. THE OPPOSITE TRAIT IS THE RECESSIVE 3. TOSS THE COIN AGAIN TO DETERMINE THE SECOND ALLELE FOR ANY DOMINANT GENOTYPE 4. COMPLETE THE PUNNETS FOR EACH TRAIT USING YOUR PARENT CHARACTER’S GENOTYPES. THESE BECOME THE TRAITS THEIR CHILD INHERITS. KERMIT EYES BLACK ee NOSE NONE SKIN GREEN MISS PIGGY EYES BLUE E e NOSE SNOUT SKIN PINK EYES ee Ee 50 E e e Ee ee e Ee ee 5. SINCE THIS SQUARE SHOWS A 50/50 CHANCE A COIN MUST BE TOSSED TO DETERMINE WHICH THE OFFSPRING WILL INHERIT BLUE Ee

EYES E BLUE BLACK e Ee ee Ee 6. TRANSFER YOUR DATA FROM THE WORKSHEET TO THIS CHART EYES E BLUE BLACK e Ee ee Ee 7. Though not required, you can select more than 5 traits. If so, complete those punnetts on a separate page then add rows to this chart

8. TOSS A COIN TO DETERMINE SEX OF THE OFFSPRING 9. DRAW YOUR OFFSPRING BASED UPON THE INHERITED TRAITS 10. TAPE, DON’T STAPLE, YOUR OFFSPRING TO THE DIAGRAM DUE ON OR BEFORE MONDAY 1/29

RR rr Rr RR Rr rr RR Rr Rr rr 1 2 3 4 5 6 Homozygous Dominant Parents Recessive Parents 2 HDP X HRP P1 3 R R r r R R RR rr Rr R r r R r r G: 4:4 Ph: 4:4 G: 4:4 Ph: 4:4 G: 4:4 Ph: 4:4 Heterozygous Parents F2 4 5 HDP X Hetero 6 HRP X Hetero R r R R r r RR Rr rr RR Rr Rr rr R R R r r r G: 1:2:1 Ph: 3:1 G: 2:4 Ph: 4:4 G: 2:4 Ph: 2:4