1. Homework #3 is due 11/19
Bonus #2 is posted
No class W 11/21
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 blue eye pigment brown hair pigment growth hormone Haploid
chromosomes
hemoglobin
DNA polymerase
similar to Fig 2.18

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

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

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

9. 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?

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. Homework #3 is due 11/19
Bonus #2 is posted
No class W 11/21
Today: Meiosis, producing genetically diverse offspring, and inheritance