1. Today: Inheritance for 1 gene

2. Fig 13.5
{Producing gametes}
Sexual reproduction creates genetic diversity by combining DNA from 2 individuals, but also by creating genetically unique gametes.
{Producing more cells}

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

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

5. In many instances there is a unique pattern of inheritance.
Fig 14.3
In many instances there is a unique pattern of inheritance.
Traits disappear and reappear in new ratios.

6. Genotype
Phenotype
Fig 14.6

7. Human blood types
Fig 14.11

8. Fig 14.11
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

9. Human blood types
Fig 14.11

10. 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

11. 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

12. What about…
RBC
Genotype = ??

13. What about…
RBC
Genotype = OO

14. What about… A B
RBC B A A B B A A B

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

16. Human blood types Phenotype Result of transfusion Phenotype Genotype
Fig 14.11
Phenotype
Phenotype
Genotype
Result of transfusion
AA or AO
BB or BO AB OO

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

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

19. 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

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

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

22. Some simple dominant/recessive relationships in humans
Fig 14.15

23. We can also predict the future
Fig 14.3

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

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

26. 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

27. Testcross: determining dominant/ recessive and zygosity
Fig 14.7

28. Sickle-cell anemia is caused by a point mutation
Fig 17.22

29. Sickled and normal red blood cells

30. Sickle-Cell Anemia: Mom = HS Dad = HS Dad H or S possible offspring
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

31. Coincidence of malaria and sickle-cell anemia
Fig 23.17
Coincidence of malaria and sickle-cell anemia

32. Sickle-Cell Anemia: Mom = HS Dad = HS possible offspring
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

33. 2 genes, each coding for a trait:
Variation in pea shape and color

34. Fig 14.8
Phenotype
Genotype

35. The inheritance of genes on different chromo- somes is independent.
Fig 14.8
The inheritance of genes on different chromo- somes is independent.

36. Approximate position of seed color and shape genes in peas
Gene for seed color Y y r R
Gene for seed shape
Chrom. 1/7
Chrom. 7/7

37. Fig 15.2
The inheritance of genes on different chromosomes is independent: independent assortment

38. Fig 15.2
meiosis I

39. Fig 15.2
meiosis I
meiosis II

40. Fig 15.2
The inheritance of genes on different chromosomes is independent: independent assortment

41. Fig 14.8

42. Next: more complex inheritance