1. Chapter 11 - Introduction to Genetics

2. Gregor Mendel Strong background in plant breeding and mathematics
Using pea plants, found indirect but observable evidence of how parents transmit genes to offspring

3. Traits
Specific characteristics that vary from one individual to another
Determined by genes
7 traits studied by Mendel
Seed shape and color, pod shape and color, position, height

4. Mendel’s Peas True Breeding
Producing offspring with traits identical to parent
Result of self-pollination of pea plants
Hybrid
Offspring that results from parents with different traits
Result of cross-pollination

5. Genes Chemical factors that determine traits (units of information)
Passed from parents to offspring
Each has a specific location (locus) on a chromosome

6. Alleles Different forms of a gene
Dominant allele (Uppercase letter) overrules a recessive allele (lowercase letter) that it is paired with

7. Principle of Dominance
Some alleles are dominant and others are recessive
Recessive allele must be present WITHOUT dominant allele, then recessive form of trait will be expressed

8. Allele Combinations Homozygous =purebred Heterozygous =hybrid
having two identical alleles at a locus
AA (dominant expressed) or aa (recessive expressed)
Heterozygous =hybrid
having two different alleles at a locus
Aa (dominant expressed)

9. Segregation
Separation of alleles during the formation of gametes (sperm and egg)

10. Tracking Generations Parental generation P mates to produce
First-generation offspring F1
which mate to produce
Second-generation offspring F2

11. Genotype & Phenotype
Genotype refers to particular genes an individual carries (represented by letters)
Phenotype refers to an individual’s physical/observable traits: actual expression of gene
Cannot always determine genotype by observing phenotype…

12. What happens when a true breeding purple flower breeds with a true breeding white flower?

13. Figure 24–5 The Structure of a Flower
Section 24-1
Filament
Anther
Stigma
Style
Ovary
Carpel
Petal
Sepal
Ovule
Stamen

14. How did Mendel fertilize the plants?

15. Mendel’s Question
Mendel wanted to know if the recessive alleles disappeared or are they still in the F1, just hidden.

16. Note differences between phenotype and genotype amongst different generations.

18. Dominant trait is expressedF M
Dominant trait is expressed
Recessive appears

19. The actual expression
Type of alleles

20. Female
Allele - different form of a gene
Male

21. Figure 11-3 Mendel’s Seven F1 Crosses on Pea Plants
Seed Shape
Seed Color
Seed Coat
Color
Pod
Shape
Pod Color
Flower Position
Plant Height
Round
Yellow
Gray
Smooth
Green
Axial
Tall
Wrinkled
Green
White
Constricted
Yellow
Terminal
Short
Round
Yellow
Gray
Smooth
Green
Axial
Tall

22. T T t t Principles of Dominance P Generation F1 Generation
Tall
Short
Tall
Tall
Tall
Tall
Tall
Short
T T t t

23. T T t t T t T t Principles of Dominance P Generation F1 Generation
Tall
Short
Tall
Tall
Tall
Tall
Tall
Short
T T t t T t T t

24. T T t t T t T t T T T t T t t t Principles of Dominance P Generation
F1 Generation
F2 Generation
Tall
Short
Tall
Tall
Tall
Tall
Tall
Short
T T t t T t T t T T T t T t t t

25. Tt X Tt Cross

26. What are the phenotypic and genotypic ratios?
Tt X Tt Cross
What are the phenotypic and genotypic ratios?

27. Dominant & Recessive Alleles
If you have attached earlobes, you inherited two copies of the recessive allele (ee)
If you have detached earlobes, you may have either two or one copy of the dominant allele (EE or Ee)

28. Earlobe Variation
Whether a person is born with attached or detached earlobes; depends on a single gene
Gene has two forms (alleles)

29. Earlobe Variation
You inherited one allele for this gene from each parent
Dominant allele specifies detached earlobes (E)
Recessive allele specifies attached earlobes (e)

31. Incomplete Dominance Neither allele is dominant over the other.
Both alleles represented by uppercase letters (RW).
Combination of red and white making a new phenotype (pink!)

32. Figure 11-11 Incomplete Dominance in Four O’Clock Flowers

33. Figure 11-11 Incomplete Dominance in Four O’Clock Flowers

34. Codominance
BOTH alleles are dominant (ex. Red flower and White flower made Red and White flower, not pink!)
Blood Type A (IA) and Blood Type B (IB), when combined make Blood Type AB

35. Multiple Alleles Genes with more than 2 alleles
Ex. With blood types there are 2 dominant alleles and 1 recessive
IA=dominant Blood Type A
IB=dominant Blood Type B
i=recessive Blood Type O

36. Figure 14-4 Blood Groups (Pg. 344-345) Safe Transfusions Phenotype
(Blood Type
Antigen on
Red Blood Cell
Genotype To
From

37. ABO Blood Type: Allele Combinations
Phenotypes: Genotypes:
Type A - IAIA or IAi
Type B - IBIB or IBi
Type AB - IAIB
Type O - ii

38. Universal Acceptor
Universal Donor

39. What percentages of offspring do you get from a mother with blood type AB and a father with blood type O?
IAIB x i i i i IA IB

40. What percentages of offspring do you get from a mother with blood type AB and a father with blood type O?
IAIB x i i i i IA
IAi
IAi IB
IBi
IBi

41. Genetic Problem - Blood Types
A man with A blood and a woman with B blood have a child. What are the chances of their child having having B blood if they are both heterozygous? What are their chances of having three children with O blood?

42. Rh factor - Another Blood Trait
Rh+ is dominant
What happens when Rh- mother is impregnated by Rh+ father?
Baby is Rh+ and mother becomes sensitized after first birth
Mother then creates antibodies to fight Rh+ blood
Further Pregnancy complications

43. Polygenic Traits More than one gene controls a trait
Skin color more than one gene, incomplete dominance
Bell Curve-used to represent frequency of polygenic traits

44. A, B, and C are dark
a, b, and c are light