1. Homework #3 is due 11/15
Bonus #2 is posted
Today: Meiosis, producing genetically diverse offspring, and inheritance

2. For life to exist, the information (genes) must be passed on.
{Meiosis:
producing gametes}
For life to exist, the information (genes) must be passed on.
{Mitosis:
producing more cells}

3. Gene for growth hormone Gene for brown hair pigment Gene for
similar to Fig 2.18
Gene for
hemoglobin
Gene for
DNA polymerase
Gene for
blue eye pigment
Haploid
chromosomes

4. Gene for growth hormone Gene for hair color Gene for hemoglobin
similar to Fig 2.18
Allele for
low express
(short)
Allele for
black hair
Allele for
sickle cell Hb
Gene for
growth hormone
Gene for
hair color
Gene for
hemoglobin
Diploid
chromosomes
Allele for
high express
(tall)
Allele for
black hair
Allele for
normal Hb

5. Each pair of chromosomes is comprised of a paternal and maternal chromosome

6. Meiosis splits apart the pairs of chromosomes.
X 23
in humans
Meiosis splits apart the pairs of chromosomes.
Fig 2.19

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

8. How does sexual reproduction generate genetic diversity?
Asexaul
Reproduction
Sexaul
Reproduction
vs.
extremely low
genetic diversity
greater genetic
diversity
How does sexual reproduction generate genetic diversity?

9. sister chromatids= replicated DNA (chromosomes)
tetrad= pair of sister chromatids
Fig 2.41

10. Meiosis splits apart the pairs of chromosomes.
X 23
in humans
Meiosis splits apart the pairs of chromosomes.
Fig 2.19

11. Crossing-over (aka Recombination) Fig 4.3 DNA cut and religated

12. Crossing-over:
Proteins in the cell cut and religate the DNA, increasing the genetic diversity in gametes.
Fig 4.5

13. Crossing-over:
Proteins in the cell cut and religate the DNA, increasing the genetic diversity in gametes.
Fig 4.4

14. Crossing-over:
Proteins in the cell cut and religate the DNA, increasing the genetic diversity in gametes.
Fig 4.5

15. How does sexual reproduction generate genetic diversity?
Asexaul
Reproduction
Sexaul
Reproduction
vs.
extremely low
genetic diversity
greater genetic
diversity
How does sexual reproduction generate genetic diversity?

16. Independent Assortment
(aka Random Assortment)
Fig 3.8

17. 2 possibilities for each pair, for 2 pairs
Independent Assortment
2 possibilities for each pair, for 2 pairs
22 = 4 combinations
Fig 3.8

18. 2 possibilities for each pair, for 23 pairs
Independent Assortment
2 possibilities for each pair, for 23 pairs
223 =
8,388,608
combinations
Fig 3.8

19. Box 2.2
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

20. Box 2.2

21. 4 haploid cells
Box 2.2

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

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

24. Do parents’ genes/traits blend together in offspring?
Fig 6.4

25. In many instances there is a unique pattern of inheritance.
Traits disappear and reappear in new ratios.
Fig 2.12

26. Genotype
Phenotype
Pg 23

27. Human blood types
Pg 225

28. One gene with three alleles controls carbohydrates that are found on Red Blood Cell membranes
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

29. Human blood types

30. 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

31. 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

32. What about…
RBC
Genotype = ??

33. What about…
RBC
Genotype = OO

34. What about… A B
RBC B A A B B A A B

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

36. Human blood types
AA or AO
BB or BO AB OO

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

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

39. 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

40. 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

41. 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

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

43. We can also predict the future
Fig 2.12

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

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

46. 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

47. 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.

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

49. Human blood types
AA or AO
BB or BO AB OO

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

51. Homework #3 is due 11/15
Bonus #2 is posted
Today: Meiosis, producing genetically diverse offspring, and inheritance