1. Bonus #2 due 4/21
Inheritance

2. How does sexual reproduction generate genetic diversity?
Asexual
Reproduction
Sexual
Reproduction
vs.
extremely low
genetic diversity
greater genetic
diversity
How does sexual reproduction generate genetic diversity?

3. Crossing-over
Meiosis:
In humans, crossing-over and independent assortment lead to over 1 trillion possible unique gametes.
(1,000,000,000,000)
Meiosis I
(Ind. Assort.)
Meiosis II
4 Haploid cells, each unique

4. {Producing gametes}
Sexual reproduction creates genetic diversity by combining DNA from 2 individuals, but also by creating genetically unique gametes.
{Producing more cells}

5. haploid
X 23
in humans
X 23
in humans
diploid
X 23
in humans
Inheritance = The interaction between genes inherited from Mom and Dad.

6. Do parents’ genes/traits blend together in offspring?

7. In many instances there is a unique pattern of inheritance.
Fig 2.6
In many instances there is a unique pattern of inheritance.
Traits disappear and reappear in new ratios.

8. from DNA to Protein: from gene to trait
Fig 1.6
from DNA to Protein: from gene to trait

9. from DNA to Protein: from gene to trait
Fig 1.7
from DNA to Protein: from gene to trait
Molecular
Cellular
Organism
Population

10. Genotype
Phenotype

11. Human blood types
Fig 4.11

12. Fig 4.11
One gene with three alleles controls carbohydrates that are found on Red Blood Cell membranes A A B
RBC A B
RBC
RBC B A B A B A A B B A A B B
Allele O = no carbs
Allele A = A carbs
Allele B = B carbs

13. Human blood types
Fig 4.11

14. We each have two versions of each gene…
RBC A A A So A A A A
Genotype could be
A and A OR
A and O

15. Recessive alleles do not show their phenotype when a dominant allele is present.
RBC A A A A A A A
Genotype could be
A and A OR
A and O
See Fig 4.2

16. What about…
RBC
Genotype = ??

17. What about…
RBC
Genotype = OO

18. What about… A B
RBC B A A B B A A B

19. What about… A B
RBC B A A B B A A B
Genotype = AB

20. Human blood types
Fig 4.11
AA or AO
BB or BO AB OO

21. If Frank has B blood type,
his Dad has A blood type,
And his Mom has B blood type…
Should Frank be worried?

22. Mom=B blood
BB or BO
Dad=A blood
AA or AO
possible
genotypes

23. Mom=B blood BB or BO Dad=A blood AA or AO all B / 50% B and 50% O
possible
genotypes
all B / 50% B and
50% O
all A / 50% A and
50% O
Gametes

24. Mom=B blood BB or BO Dad=A blood AA or AO all B / 50% B and 50% O
Possible
genotypes
all B / 50% B and
50% O
all A / 50% A and
50% O
Gametes
Frank can be BO
= B blood
…no worries

25. Mom=B blood BB or BO Dad=A blood AA all B / 50% B and 50% O Gametes
Grandparents
AB and AB
Mom=B blood
BB or BO
Dad=A blood AA
possible
genotypes
all B / 50% B and
50% O
Gametes
all A
Frank can be BO or BB
= B blood
…Uh-Oh

26. Pedigree, tracing the genetic past
Dom.
Rec.
Rec.
Dom.

27. Fig 2.11

28. We can also predict the future
Fig 2.6

29. Inheritance of blood types
Mom = AB
Dad = AB

30. Inheritance of blood types
Mom = AB
Dad = AB
Gametes:
A or B
A or B

31. Mom = AB Dad = AB A or B A or B Gametes: Dad A or B 25% AA 50% AB
Inheritance of blood types
Mom = AB
Dad = AB
A or B
A or B
Gametes:
Dad
A or B
Chance of each phenotype for
each offspring
25% AA
50% AB
25% BB AA
A or B AB
Mom AB BB

32. Single genes controlling a single trait are unusual
Single genes controlling a single trait are unusual. Inheritance of most genes/traits is much more complex…
Dom.
Rec.
Rec.
Dom.

33. Genotype
Phenotype
Genes code for proteins (or RNA). These gene products give rise to traits…

34. Human blood types
Fig 4.11
AA or AO
BB or BO AB OO

35. Genotype
Phenotype
Genes code for proteins (or RNA). These gene products give rise to traits…
It is rarely this simple.

36. Fig 4.3
Incomplete dominance

37. Fig 4.4

38. Sickle-cell anemia is caused by a point mutation
Fig 4.7

39. Sickle and normal red blood cells
Fig 4.7
Sickle and normal red blood cells

40. Sickle-Cell Anemia: Mom = HS Dad = HS Dad H or S possible offspring
Fig 4.7
Sickle-Cell Anemia:
A dominant or recessive allele?
S=sickle-cell
H=normal
Mom = HS
Dad = HS
Dad
H or S
possible offspring
75% Normal
25% Sickle-cell HH HS
H or S
Mom HS SS

41. Coincidence of malaria and sickle-cell anemia
Fig 24.14

42. Sickle-Cell Anemia: Mom = HS Dad = HS possible offspring
Fig 4.7
Sickle-Cell Anemia:
A dominant or recessive allele?
S=sickle-cell
H=normal
Mom = HS
Dad = HS
possible offspring
Oxygen transport:
75% Normal
25% Sickle-cell
Malaria resistance:
75% resistant
25% susceptible
Dad
H or S HH HS
H or S
Mom HS SS

43. The relationship between genes and traits is often complex
Complexities include:
Complex relationships between alleles

44. Fig 3.18
Sex determination is normally inherited by whole chromosomes or by number of chromosomes.

45. X/Y chromosomes in humans

46. 105 males : 100 females (live births)
Why?

47. 105 males : 100 females (live births)
Why?

49. The X chromosome has many genes; the Y chromosome only has genes for maleness.

50. Sex-linked traits are genes located on the X chromosome

51. Color Blind Test

52. No one affected, female carriers
Sex-linked traits: Genes on the X chromosome
A= normal;
a= colorblind
colorblind
normal
No one affected, female carriers
similar to Fig 4.13

53. 50% of males affected, 0 % females affected
Sex-linked traits: Genes on the X chromosome
A= normal;
a= colorblind
normal
normal
50% of males affected,
0 % females affected
similar to Fig 4.13

54. 50% males affected, 50% females affected
Sex-linked traits: Genes on the X chromosome
A= normal;
a= colorblind
colorblind
normal
50% males affected,
50% females affected
similar to Fig 4.13

55. Sex-linked traits: Genes on the X chromosome A= normal ; a= colorblind
No one affected, female carriers
50% of males affected, 0 % female affected
50% males affected, 50% females affected
similar to Fig 4.13

56. Fig 3.18
For Th:
Males and females may have different numbers of chromosomes. This must be compensated for.