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Genetics History

Genetics History. Kobe Lottery. Directions: I am going to roll 6 dice…one at a time. If you guess the 6 numbers in order, you will win a prize. Gregor Mendel. “Father of Genetics” Famous for pea plant studies Mendel studied seven pea plant traits

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Genetics History

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  1. Genetics History

  2. Kobe Lottery • Directions: I am going to roll 6 dice…one at a time. If you guess the 6 numbers in order, you will win a prize.

  3. Gregor Mendel • “Father of Genetics” • Famous for pea plant studies • Mendel studied seven pea plant traits • Results shaped our understanding of genetics

  4. Genetics: Study of heredity Heredity: passing of traits from parent to child Patterns of relatedness can help predict offspring characteristics What is Genetics?

  5. Mendel’s 7 traits studied

  6. Pure Breeding Purple & White Flowers Parent Generation (P) Mendel crossed a purple flower with a white flower. 1st Generation (F1) Mendel crossed 2 F1 purple flowers. Result: 75% purple flowers, 25% white flower (3:1 ratio) Result: 100% offspring were purple (even though one parent was white)

  7. Each trait had a 3:1 ratio. No way that can be a coincidence!

  8. Mendel's Conclusion • 1 gene may prevent the expression of another • Organisms inherit 2 copies of each gene • One from each parent

  9. Chromosomes and Genes • Genes are pieces of DNA that create proteins: • located on chromosomes • inherited from parents • come in dominant & recessive forms (alleles) • Ex: Flower color • Purple allele (dominant) • White (recessive) • Letters used to abbreviate alleles • Dominant Allele = Capital letter • Recessive Allele = Lowercase letter

  10. Genotypes • Defined: Genetic makeup of an organism • Homozygous dominant: combination of two dominant alleles (PP) • Heterozygous: combination of one dominant, one recessive allele (Pp) • Homozygous recessive: combination of two recessive alleles (pp)

  11. Phenotype • Defined: Physical appearance of a gene • Example: • What’s the phenotype of a flower that is PP genotype? __________ • What’s the phenotype of a flower with Pp genotype? ___________ • What’s the phenotype of a flower with a pp genotype? __________ Purple Purple White

  12. Genetics Vocabulary Review Choices: • YY • Tall • Yy • SS • yY • gg • Smooth • Green • TT • Dwarf Which choice(s) are examples of: Genotypes? 1, 3, 4, 5, 6, 9 Phenotypes? 2, 7, 8, 10 Homozygous genotypes? 1, 4, 6, 9 Heterozygous genotypes? 3, 5 Homozygous recessive genotypes? 6 Homozygous dominant genotypes? 1, 4, 9

  13. Cross a homozygous dominant yellow (YY) plant with a homozygous recessive green (yy) plant y y y y y y Key Y = yellow y = green Y Y Y Y Y Y 100% Probability of growing a yellow plant? _____________ 0% Probability of growing a homozygous recessive plant? ____________ 0% Probability of growing a homozygous dominant plant? ____________

  14. Cross a heterozygous dominant yellow (Yy) plant with a heterozygous dominant yellow (Yy) plant Y Y Y y y y Y Y Y Key Y = Yellow y = green y y y 50% Probability of growing a heterozygous plant? ________ 25% Probability of growing a green plant? ________ 25% Probability of growing pure yellow? _________

  15. Kobe Kuiz 1) How are dominant alleles expressed? Recessive? 2) Which of the following are genotypes? Phenotypes? TT Green yY Pp Purple gg Smooth 3) Which of the following are heterozygous genotypes? TT Green yY Pp Purple gg Smooth 4) Genes may often be found in two forms (dominant and recessive). What are these alternate forms of a gene called? 5) Genes are segments of DNA found on _______________. 6) If item A is found in a 2:1 ratio compared to item B, what percentage is item A? 7) If item A is found in a 4:1 ratio compared to item B, what percentage is item A? 8) Cross a heterozygous tall with a homozygous recessive short pea plant. List the genotypes in a Punnett square. What’s the probability of growing a tall plant? What’s the probability of growing a homozygous dominant plant? What’s the probability of growing a homozygous recessive plant?

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