1. Homework #4 is due 12/4/07 (only if needed)
Bonus #2 posted
Year End Topics:
mtDNA
Mapping
Probability
Evolution and the Origin of Humans

2. Grades:
A = 88.5+
B = 77.5
C = 65.5
Exam avg x homework + bonus = grade Final time?

3. Genotype
Phenotype
Dominant
Recessive

4. 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

5. The relationship between genes and traits is often complex
Complexities include:
Complex relationships between alleles
Multiple genes controlling one trait
One gene controlling multiple traits
Environmental effects

6. Only the egg provides mitochondria to the offspring.
Pg 112

7. Human
Life
Cycle
In females Mom provides % and Dad provides % of DNA to offspring.
… because Mom provides 100% of mitochondrial DNA

8. A few diseases are caused by mutations in mtDNA
Fig 3.24

9. Pedigree of a mitochondrial disease: Which shape represents females?
Fig 3.25

10. Pedigree of a mitochondrial disease:
Males and females may be affected by a disease coded on mtDNA, but only females pass it on.
Fig 3.25

11. For our final lecture of the semester, we will look at what DNA can tell us about the origins of Homo sapiens.

12. Variation in Peas
Fig 3.2

13. Phenotype
Genotype
Fig 3.3

14. Tracking two separate genes, for two separate traits, each with two alleles.
Ratio of 9:3:3:1
Fig 3.4

15. 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

16. Recombinants are meiotic output different from meiotic input
Fig 3.11

17. 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

18. Linked alleles tend to be inherited together
Fig 4.2

19. Crossing over produces new allelic combinations
Fig 4.3

20. Recombinants are produced by crossing over
Fig 4.7

21. For linked genes, recombinant frequencies are less than 50 percent
Fig 4.8

22. Homologous
pair of chromosomes

23. Does this pedigree show recombination or linkage?
Fig 4.23

24. Does this pedigree show recombination or linkage?
Fig 4.23

25. Longer regions have more crossovers and thus higher recombinant frequencies
Fig 4.10

26. Some crosses do not give the expected results

27. =25%
42%
41% 9% 8%

28. These two genes are on the same chromosome

30. By comparing recombination frequencies, a linkage map can be constructed
= 17 m.u.

31. Another test

32. 42 recombinants out of 381 offspring =
42/381
11% recombination

33. The probability of crossing over can be used to determine the spatial relationship of different genes
Fig 4.9

34. Double recombinants arise from two crossovers
Fig 4.11

35. Double recombinants can show gene order
Fig 4.12

36. What is the relationship between these 3 genes
What is the relationship between these 3 genes? What order and how far apart?
similar to pg 141

37. What is the relationship between these 3 genes
What is the relationship between these 3 genes? What order and how far apart?
similar to pg 141

38. Double crossover
similar to pg 141

39. Which order produces the double crossover?

40. Which order produces the double crossover?

41. We have the order. What is the distance?
similar to pg 141

42. Recombinants between st and ss: (50+52+5+3)/755 =14.6%
similar to pg 141

43. Recombinants between ss and e: (43+41+5+3)/755 =12.2%
similar to pg 141

44. Put it all together…
26.8 m.u. st ss e
14.6 m.u.
12.2 m.u.

45. Linkage map of Drosophila chromosome 2

46. Recombination is not completely random.
physical distance
linkage map
Yeast chromosome 3
Fig 4.13 and 20

47. Alignment of physical and recombination maps
Fig 4.25

48. 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

49. The relationship between genes and traits is often complex
Complexities include:
Complex relationships between alleles
Multiple genes controlling one trait
One gene controlling multiple traits
Environmental effects

50. Homework #4 is due 12/4/07 (only if needed)
Bonus #2 posted
Year End Topics:
mtDNA
Mapping
Probability
Evolution and the Origin of Humans