1. Mendelelian Genetics Mendelian Genetics 1/16/2019
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2. Gregor Mendel (1822-1884) Discovered the laws of HEREDITY
Mendelian Genetics
1/16/2019
Gregor Mendel ( )
Discovered the laws
of HEREDITY
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3. Gregor Johann Mendel Austrian monk
Mendelian Genetics
1/16/2019
Gregor Johann Mendel
Austrian monk
Studied the inheritance of traits in pea plants
Mendel's work was not recognized until the turn of the 20th century
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4. Mendelian Genetics
1/16/2019
Gregor Johann Mendel
Between 1856 and 1863, Mendel cultivated and tested some 28,000 pea plants
He found that the plants' offspring retained traits of the parents
Called the “Father of Genetics"
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5. Traits
Genetics – study of how traits are passed from parent to offspring

6. Particulate Inheritance
Mendelian Genetics
1/16/2019
Particulate Inheritance
Mendel stated that physical traits are inherited as “particles”
Mendel did not know that the “particles” were actually Chromosomes & DNA
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7. Traits are determined by the genes on the chromosomes
Traits are determined by the genes on the chromosomes. A gene is a segment of DNA that determines a trait.

8. P
(Parent generation) F1 F2
(3:1)

9. Why peas, Pisum sativum? Can be grown in a small area
Mendelian Genetics
1/16/2019
Why peas, Pisum sativum?
Can be grown in a small area
Produce lots of offspring
Produce pure plants when allowed to self-pollinate several generations
Can be artificially cross-pollinated
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10. Mendelian Genetics
1/16/2019
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11. Mendelian Genetics
1/16/2019
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12. Humans have 46 chromosomes or 23 pairs. One set from dad – 23 in sperm
One set from mom – 23 in egg

13. Mendelian Genetics
1/16/2019
Genetics Terminology
Dominant allele- stronger of two genes expressed in the hybrid; represented by a capital letter (R)
Recessive allle - gene that is masked by the dominant allele; represented by a lowercase letter (r)
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14. Genetics Terminology Phenotype – expressed traits (observable)
Mendelian Genetics
1/16/2019
Genetics Terminology
Genotype- genetic make-up (letters)
Ex. AA, Aa, aa
Phenotype – expressed traits (observable)
Ex. Tall, short, brown hair
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15. Genetics Terminology Heterozygous genotype – different alleles Ex. Aa
Mendelian Genetics
1/16/2019
Genetics Terminology
Homozygous genotype- same alleles
Ex. AA, aa
Heterozygous genotype – different alleles
Ex. Aa
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16. Genetics Terminology Alleles– alternate forms of a gene Ex. A and a
Mendelian Genetics
1/16/2019
Genetics Terminology
Gene- section of DNA or chromosome that codes for a PROTEIN or TRAIT
Alleles– alternate forms of a gene
Ex.
A and a
A and A
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17. Mendelian Genetics
1/16/2019
Genetic Terminology
Trait - any characteristic that can be passed from parent to offspring
Heredity - passing of traits from parent to offspring
Genetics - study of heredity
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18. Types of Genetic Crosses
Mendelian Genetics
1/16/2019
Types of Genetic Crosses
Monohybrid cross - cross involving a single trait e.g. flower color
Dihybrid cross - cross involving two traits e.g. flower color & plant height
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19. Mendelian Genetics
1/16/2019
Monohybrid Crosses
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20. P1 Monohybrid Cross r r Rr Rr R R Rr Rr Trait: Seed Shape
Mendelian Genetics
1/16/2019
P1 Monohybrid Cross
Trait: Seed Shape
Alleles: R – Round r – Wrinkled
Cross: Round seeds x Wrinkled seeds
RR x rr
Genotype: Rr
Phenotype: Round
Genotypic Ratio: All alike
Phenotypic Ratio: All alike r r Rr Rr R R Rr Rr
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21. P1 Monohybrid Cross Review
Mendelian Genetics
1/16/2019
P1 Monohybrid Cross Review
Homozygous dominant x Homozygous recessive
Offspring all Heterozygous (hybrids)
Offspring called F1 generation
Genotypic & Phenotypic ratio is ALL ALIKE
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22. F1 Monohybrid Cross R r RR Rr R r Rr rr Trait: Seed Shape
Mendelian Genetics
1/16/2019
F1 Monohybrid Cross
Trait: Seed Shape
Alleles: R – Round r – Wrinkled
Cross: Round seeds x Round seeds
Rr x Rr
Genotype: RR, Rr, rr
Phenotype: Round & wrinkled
G.Ratio: 1RR:2Rr:1rr
P.Ratio: 3:1 R r RR Rr R r Rr rr
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23. F1 Monohybrid Cross Review
Mendelian Genetics
1/16/2019
F1 Monohybrid Cross Review
Heterozygous x heterozygous
Offspring: 25% Homozygous dominant RR 50% Heterozygous Rr 25% Homozygous Recessive rr
Offspring called F2 generation
Genotypic ratio is 1:2:1
Phenotypic Ratio is 3:1
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24. Breed the P1 generation tall (TT) x dwarf (tt) pea plants t T
Mendelian Genetics
1/16/2019
Breed the P1 generation
tall (TT) x dwarf (tt) pea plants t T
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25. tall (TT) vs. dwarf (tt) pea plants
Mendelian Genetics
1/16/2019
Solution:
tall (TT) vs. dwarf (tt) pea plants T t
All Tt = tall
(heterozygous tall)
produces the
F1 generation Tt
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