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Chapter 14 Part I: Mendel and Chapter 14 Part I: Mendel and the Gene Idea the Gene Idea • This chapter details Mendel’s discovery of general laws of heredity as well as monohybrid dihybrid genetic crosses.
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Chapter 14 Part I: Mendel and the Gene Idea This chapter details Mendel’s discovery of general laws of heredity as well as monohybrid dihybrid genetic.

Dec 16, 2015

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Morris Heath
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Page 1: Chapter 14 Part I: Mendel and the Gene Idea This chapter details Mendel’s discovery of general laws of heredity as well as monohybrid dihybrid genetic.

Chapter 14 Part I: Mendel and Chapter 14 Part I: Mendel and the Gene Ideathe Gene Idea

• This chapter details Mendel’s discovery of general laws of heredity as well as monohybrid dihybrid genetic crosses.

Page 2: Chapter 14 Part I: Mendel and the Gene Idea This chapter details Mendel’s discovery of general laws of heredity as well as monohybrid dihybrid genetic.

A. Gregor MendelA. Gregor Mendel

1 Austrian Monk

2 Formulated two laws of inheritance in 1860s.

3 Previously studied math and science at University of Vienna.

Page 3: Chapter 14 Part I: Mendel and the Gene Idea This chapter details Mendel’s discovery of general laws of heredity as well as monohybrid dihybrid genetic.

B. Blending Concepts of B. Blending Concepts of InheritanceInheritance

1 Theory stated that offspring would possess traits intermediate between those of different parents.

2 Red and White flowers make Pink flowers.

3 Darwin wanted to develop a theory of evolution based on Mendel’s heredity principles.

Page 4: Chapter 14 Part I: Mendel and the Gene Idea This chapter details Mendel’s discovery of general laws of heredity as well as monohybrid dihybrid genetic.

C. Mendel’s Experimental C. Mendel’s Experimental ProcedureProcedure

1 Mendel did a statistical study

2 Prepared experiments carefullyA . Garden PeaB . 22 true-breeding varietiesC . Simple traits were studied

3 Mendel traced inheritance of individual traits.

4 Principles of probability used for interpretation.

Page 5: Chapter 14 Part I: Mendel and the Gene Idea This chapter details Mendel’s discovery of general laws of heredity as well as monohybrid dihybrid genetic.

11.2 Monohybrid Inheritance11.2 Monohybrid Inheritance

A . Cross-pollination Monohybrid Crosses1 A hybrid is result of 2 true-breeding parents2 A monohybrid cross is between two true-breeding parents for two distinct

forms of a trait.3 Mendel tracked 2 generations

A . P GenerationB . F1 GenerationC . F2 Generation

Page 6: Chapter 14 Part I: Mendel and the Gene Idea This chapter details Mendel’s discovery of general laws of heredity as well as monohybrid dihybrid genetic.

B. Mendel’s ResultsB. Mendel’s Results

1 Contrary results to predictions

2 F1 resembled one parent

3 1/4 of F2 resembled one parent; 3/4 resembled other parent like F1 generation.

4 3:1 ratio resultsA . Dominant/recessive shown in F2.B . Factors separated when gametes were formed.C . Random fusion upon fertilization.

Page 7: Chapter 14 Part I: Mendel and the Gene Idea This chapter details Mendel’s discovery of general laws of heredity as well as monohybrid dihybrid genetic.

B. Mendel’s Results ContinuedB. Mendel’s Results Continued

5 Mendel’s First Law of Inheritance: Law of SegregationA. Each organism contains 2 factors for each

trait; factors segregate in formation of gametes; each gamete contains one factor for each trait.

B . Factors passed from generation to generation

Page 8: Chapter 14 Part I: Mendel and the Gene Idea This chapter details Mendel’s discovery of general laws of heredity as well as monohybrid dihybrid genetic.

C. As Viewed by Modern C. As Viewed by Modern Genetics Genetics

1 Traits controlled by two alleles, alternate forms of trait found at the same gene locus.

2 Gene locus is a specific location on a gene

3 Homozygous is two identical alleles for a trait.A . Homozygous dominant - 2 dominant allelesB . Homozygous recessive - 2 recessive alleles

4 After cross-pollination, all F1 are heterozygous genotypes.

Page 9: Chapter 14 Part I: Mendel and the Gene Idea This chapter details Mendel’s discovery of general laws of heredity as well as monohybrid dihybrid genetic.

D. Genotype Vs. PhenotypeD. Genotype Vs. Phenotype1 2 organisms with different allele combinations can

have same outward appearance (TT & Tt)

2 Genotype refers to alleles at fertilization.

3 Phenotype refers to physical appearance.

Page 10: Chapter 14 Part I: Mendel and the Gene Idea This chapter details Mendel’s discovery of general laws of heredity as well as monohybrid dihybrid genetic.

E. Laws of ProbabilityE. Laws of Probability

1 Probability is the likely outcome a given event will occur from random chance.

2 Multiplicative law of probability = chance of 2 or more independent events occurring together is the product of the probability of the events occurring separately

3 Additive law of probability = probability of an event that occurs in 2 or more independent ways.

Page 11: Chapter 14 Part I: Mendel and the Gene Idea This chapter details Mendel’s discovery of general laws of heredity as well as monohybrid dihybrid genetic.

F. The Punnet SquareF. The Punnet Square

1 Provides simple method to calculate probable results of genetic cross.

2 Sperm cells lined up vertically; egg cells lined up horizontally.

3 Larger sample sizes give better outcomes for predicted ratios.

4 Humans use phenotypic rations for predictions.

Page 12: Chapter 14 Part I: Mendel and the Gene Idea This chapter details Mendel’s discovery of general laws of heredity as well as monohybrid dihybrid genetic.

G. One-Trait TestcrossG. One-Trait Testcross1 Mendel performed testcrosses by crossing F1 to

homozygous recessive.2 Results indicated recessive factor in F1.3 Testcross = dominant phenotypic individual crossed with

recessive individual.

Page 13: Chapter 14 Part I: Mendel and the Gene Idea This chapter details Mendel’s discovery of general laws of heredity as well as monohybrid dihybrid genetic.

11.3 Dihybrid Inheritance11.3 Dihybrid InheritanceA . Dihybrid Crosses1 Dihybrid cross is an experimental

cross between 2 true-breeding parents for 2 different traits.

B . Plants Self-Pollinate1 Mendel observed 4 phenotypes among

F2.2 This gave him Second Law of Heredity:

law of independent assortment.A . Members assort independently of

each other.

Page 14: Chapter 14 Part I: Mendel and the Gene Idea This chapter details Mendel’s discovery of general laws of heredity as well as monohybrid dihybrid genetic.

C. Dihybrid Genetics ProblemsC. Dihybrid Genetics Problems

1 Laws of probability indicate a 9:3:3:1 phenotypic ratio of F2.A. 9/16 dominant for both traitsB . 3/16 dominant for 1 trait, recessive for otherC . 3/16 dominant/recessive opposite of previousD. 1/16 recessive for both traits

2 9:3:3:1 ratio expected when heterozygous for 2 traits are crossed.

Page 15: Chapter 14 Part I: Mendel and the Gene Idea This chapter details Mendel’s discovery of general laws of heredity as well as monohybrid dihybrid genetic.

D. Two-Trait Test CrossD. Two-Trait Test Cross

1 Dihybrid Test Cross - homozygous dominant traits or heterozygous.

2 Dihybrid genetic problems: 4 alleles for 2 traits.

END OF CHAPTER 11