1. Genetics

2. Which one of these is not like the other???

3. Mutants

4. Mutants

5. Contrasting Traits
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6. Relationship of Phenotype to Genotype
The phenotype is the outward expression of all alleles governing a given trait
The genotype is the alleles present in the genome
The gene products encoded by the gene (alleles) give rise to the phenotype

7. A Controlled Cross between Two Plants
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8. Mendel’s Experiment 1 (Part 1)
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9. Mendel’s Experiment 1 (Part 2)
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10. Mendel’s Explanation of Experiment 1
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11. Phenotype Dominant trait One that appears exclusively in F1 generation
Recessive trait
One masked in the F1 but reappearing in some of F2 offspring

12. Mendel’s Monohybrid Cross Results

13. Mendel’s Law of Segretation
Each parent contains two factors governing a particular trait
2 dominants
1 dominant + 1 recessive
2 recessives
The factors are separated during reproduction and only 1 from each parent is passed to offspring
Alleles of a gene segregate during meiosis
Each somatic cell contains 2 alleles of each gene, while gametes contain only 1.

14. Meiosis Accounts for the Segregation of Alleles
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15. Meiosis Accounts for the Segregation of Alleles
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16. Homozygosity vs Heterozygosity
alleles are same
Heterozygosity
alleles are different
Homozygous dominant and heterozygous individuals have same phenotype (dominant)
Homozygous recessive individuals have recessive phenotype

17. Homozygous or Heterozygous?
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18. Dihybrid Crosses and Independent Assortment
What is result of crosses between individuals differing in two traits?
Do alleles of for different traits segregate together or separately?
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19. Meiosis Accounts for Independent Assortment of Alleles
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20. Relationships between Alleles
In diploid organisms there are 2 alleles for every gene (locus) in the genome
One allele was inherited from father and the other from mother
Multiple alleles may exist in a population of organisms although only 2 are present at any one time in an individual
Each gene encodes a gene product (protein or RNA)
Alleles interact in following ways
Complete dominance/recessiveness
Co-dominance
Incomplete dominance

21. Phenotype vs Genotype Phenotype – appearance/function
Genotype – set of alleles present in genome

22. ABO Blood Types: Multiple Alleles Showing Complete Dominance or Co-dominance
Phenotype
A dominant to O
B dominant to O
A co-dominant to B
Co-dominance results when alleles each encode a functional enzyme, however, the encoded enzymes differ in their specificities
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23. Incomplete Dominance r encodes a non-functional protein
R encodes a functional protein
Rr makes ½ the amount of R-protein as an RR flower
Rr flowers are less intensely colored
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24. Pedigree Analysis
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25. Pedigree Analysis
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26. Crossing Over Results in Genetic Recombination
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27. Linkage: When Alleles Do Not Sort Independently
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28. Recombinant Frequencies
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29. Steps toward a Genetic Map
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30. Map These Genes (Part 1)
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31. Map These Genes (Part 2)
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32. Figure 10.22 Map These Genes (Part 3)
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33. Figure 10.22 Map These Genes (Part 4)
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34. Figure 10.22 Map These Genes (Part 5)
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35. Eye Color Is a Sex-Linked Trait in Drosophila
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36. Figure 10.24 Red-Green Color Blindness is a Sex-Linked Trait in Humans
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37. Epistasis
Epistasis occurs when the alleles of one gene cover up or alter the expression of alleles of another gene.
Coat color in mice:
B allele produces a banded pigment pattern, called agouti, while the b allele results in unbanded hairs.
genotypes BB or Bb produce agouti. genotype bb is black.
Alleles at the A locus determine if any pigment is made. The genotypes AA and Aa have color and aa are albino.
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38. Epistatic Gene Interaction
Sequential pigment deposition B b
Constant pigment deposition
B is an enzyme that actively interupts deposition
Non-functional pigment producing enzyme A a
Functional pigment producing enzyme
A is an enzyme that actively synthesizes pigment

39. Epistasis genotype Pigment producing enzyme
Deposition of pigment in hair
pigment precursor molecule
pigment molecule
pigmented hair
AA or Aa
pigment precursor molecule
pigment molecule
BB or Bb
Striped hair
genotype aa
pigment precursor molecule
pigment molecule
BB or Bb
pigmented hair
AA or Aa
pigment precursor molecule
pigment molecule bb
Solid color hair aa
pigment precursor molecule
pigment molecule bb
pigmented hair

40. Quantitative Traits
Traits exhibiting a range of phenotypic variance that can be quantified (measured)
Height, weight, seed yield, life span etc…
Traits are simultaneously controlled by many alleles
Additive alleles
Proteins encoded by various alleles function in tandem to influence trait
Genes functioning in this manner are referred to as quantitative trait loci (QTLs)

41. Quantitative Trait Loci
2 genes control seed color for a given plant and each gene has 2 alleles
Genes: A/a, B/b, Any given plant can be of one of the following genotypes
AABB, AaBB, aaBB, AABb, AAbb, AaBb, Aabb, aaBb, aabb
Each allele of each gene can “add” a given amount of activity to generating a color phenotype.
A and B add the most color, a and b add less color
Therefore a range of colors can exist (5 categories)
AABB – darkest
AABb, AaBB – next darkest
AaBb, aaBB, AAbb – mid range color
Aabb, aaBb – very little color
aabb – least color