7 Genetics

Gregor Mendel and the Garden Pea (page 117)page 117 Genetics: the study of heredity; how an offspring gets traits from their parents. Describe Gregor Mendel. Who? Monk (priest) What? Curious gardener trained in math and science When? 1860s Where? Austria How did Mendel add a “twist” to his research? He used math to draw conclusions from his observations.

List 4 reasons why the garden pea was a good subject for scientific study. 1. easy to grow 2. grow quickly 3. large number of offspring; a lot of quantitative data 4. plants have both male and female parts; fertilization can be controlled Define self-fertilization: plant that fertilizes itself Define cross-fertilization: plant that is fertilized by another plant

Mendel’s Experiment (page 118)page 118 Step One: Creating the parent (P) generation (Pure Breeding) allowed plants to self-fertilize for many generations collected and grew the seeds from the plants observed that purple flowering seeds grew purple flowers and white flowering seeds grew white flowers. CREATED PURE BREEDING PLANTS

Step Two: Cross breeding plants from parent generation to create F1 generation. used pollen from purple flower and fertilized white flower collected and grew seeds only purple flowers grew from this generation. Results of Step Two: When Mendel cross fertilized a true breeding purple plant with a true breeding white plant, all of the offspring had purple flowers. Mendel asks…Where did the white flowers go? Hypothesis…even though the flowers were all purple, they must be carrying around some kind of white flowering plant “factors”.

Step Three: Self-pollinate one of the offspring from the F1 generation to create the F2 generation. self-fertilized a purple flowered plant from the F1 generation collected and grew the seeds purple and white flowers showed up on the plants For every 4 flowers on the plants, 1 one was white and 3 were purple. 3:1 Ratio in the F2 generation

Mendel’s Quantitative Results: Total Pea Plants in F2 Generation = ___________ Pea Plants with Purple Flowers = ___________ Pea Plants with White Flowers = ___________ What % of Mendel’s F2 Generation had purple flowers? (purple flowers / total flowers) x 100 = __________% What % of Mendel’s F2 Generation had white flowers? (white flowers / total flowers) x 100 = ___________% The ratio of purple to white flowers in Mendel’s F2 Generation is ____ : _____. List three other pea plant traits that Mendel studies

TraitContrasting Form of Traits F2 Generation RatiosWhich trait showed up more often? Flower ColorPurple and White705:224Purple Seed Color6,022:2,001Yellow Round and Wrinkled Round Pod Color428:152 Mendel’s Experiments (page 119)page 119 Use Table 7-1 on page 119 to complete the missing boxes in the chart below. Contrasting Traits in Pea Plants

Mendel’s Explanation of the Results (VERY IMPORTANT VOCABULARY) Factors: “information” that is trasfered from parent to offspring Traits: characteristic you get from your parents (ex: hair color) Alleles: different forms of this information; types of traits (ex: brown vs. blonde) Principle of Dominance: some alleles are more dominant than others Dominant Traits: traits that show up more often in a population; stronger allele (ex: brown eyes) Recessive Traits: traits that show up less often in a population; weaker allele (ex: red hair)

Genotype: type of alleles passed from parent to offspring; “your two letters” Homozygous (pure bred): contain two of the same allele for a trait (ex: both parents pass brown eyes to their offspring Heterozygous (hybrid): contain two different alleles for a trait (ex: one parent passed brown eyes and the other passed blue eyes) Dominant Allele + Dominant Allele = dominant trait Dominant Allele + Recessive Allele = dominant trait Recessive Allele + Recessive Allele = recessive trait Phenotype: physical appearance of a trait (brown eyes)

The Principle of Dominance Related to some Simple Human Traits TRAIT Your PhenotypeDominant trait? Recessive trait? Class Ratio Dominant to Recessive Frequency % of your trait Tongue rolling Skin appearance of freckles Hairline Dimples PTC Ear lobe Bent fingers Thumb Finger hair

Mendel’s Conclusions (page 122)page 122 Law of Segregation: when gametes (sex cells) are made, the two alleles for each trait will separate; gametes only carry one of each allele. Bill Nye: Understanding Basic Genetics

Segregation of Alleles and Fertilization of Gametes Directions: Complete each chart using the given information. Collect quantitative data using the information within the completed chart. 1.True breeding Yellow Seeds x True Breeding Green Seeds Dominant Trait: ______________ Domiant Allele: _____ Recessive Trait: ______________ Recessive Allele: _____ # Dominant _________ # Recessive _________ % Dominant _________ % Recessive ________ Ratio ____: ____

Segregation of Alleles and Fertilization of Gametes Directions: Complete each chart using the given information. Collect quantitative data using the information within the completed chart. 2. Hybrid Green Pea Pod x Hybrid Green Pea Pod Dominant Trait: ______________ Domiant Allele: _____ Recessive Trait: ______________ Recessive Allele: _____ # Dominant _________ # Recessive _________ % Dominant _________ % Recessive ________ Ratio ____: ____

Punnett Square: diagram used to show genetic crosses (segregation and fertilization of alleles) Probability: the likelihood that something will happen Visualizing Mendel’s Model (pages 120-1) Choose a letter to represent the trait being modeled Upper case letter represents dominant form of trait (dominant allele) Lower case letter represents recessive allele Parent genotypes go on the outside of the box (segregating one allele to each box) Offspring genotypes (fertilized together) go on the inside of the boxes

Phenotype of the Parent Generation: _______and_____________ Genotype of the Parent Generation: _______and_____________ Punnett Square Modeling Mendel’s Parent to F1 Generation: Flower Color

Punnett Square Modeling Mendel’s F1 to F2 Generations: Flower Color Phenotype of the Parent Generation: _______and_____________ Genotype of the Parent Generation: _______and_____________ Sponge Bob Genetics