1. Item 52: Exceptions to the Rule

2. Incomplete Dominance:
The blending of alleles Ex: Red Flower + White Flower = Pink Flower

3. Incomplete Dominance
For a trait, the “dominant” is not completely masking the recessive
No lower case letters
Get blending in heterozygous

4. Incomplete Dominance R = red, r = white RR = red, R = red, W = white
Normally:
Incomplete Dominance:
R = red, r = white
RR = red,
Rr = red
rr = white
R = red, W = white
RR = red
RW = pink
WW = white

5. Incomplete Dominance
One red and one white flower are cross pollinated (mated), draw the punnett square of their offspring:
R R W RW

6. Incomplete Dominance
One red and one pink flower are cross pollinated (mated), draw the punnett square of their offspring:
R R R W RR RW

7. Co-Dominance
Both are dominant so both show

8. Co-Dominance
For a trait, you can have 2 dominant options and 1 recessive
Can’t use regular upper and lowercase

9. Co-dominance R = red, r = white RR = red, Rr = red rr = white
Normally
Co-dominance
R = red, r = white
RR = red,
Rr = red
rr = white
R= red, W = white, recessive = yellow
IRIR or IRi= red
IWIW or IWi= white
IRIW – red and white
ii = yellow

10. Practice problem…do somewhere in your notes
A flower with red and white stripes mates with a homozygous white flower. What is the phenotypic ratio?

11. Co-dominance Example: Blood types A and B are co-dominant – AB
O is recessive
Genotypes:
A -> IAIA and IAi AB -> IAIB
B -> IBIB and IBi O -> ii

12. Co-dominance Blood transfusions:
Must receive blood type you are OR recessive (__O__)
O is universal donor
AB is universal acceptor

13. Warm Up
1.) Draw the Punnett square for a man who is heterozygous for B type blood and a woman who has O type blood. What are the blood type possibilities for their children?
2.) Snapdragons are flowers that exhibit incomplete dominance. Show the Punnett square cross between a pink flower and a white flower. What is the phenotypic ratio (pink to white)?

14. Snapdragons

15. Karyotypes Karyotype – map of our chromosomes
Normal Human karyotypes have 23 pairs of chromosomes – 46 total chromosomes

16. Karyotypes Pairs 1-22 “autosomes” code for body features
Pair 23 “sex chromosomes” determine gender
XX  female
XY  male

17. Who decides? X X Mom can give X X Dad can give X or y y X X X X X y
SO ____ determines sex of the baby.
If dad gives X with mom’s X = girl
If dad give y with mom’s X = boy

18. SEX DETERMINATION
XX =
female

19. SEX DETERMINATION
Xy =
male

20. Karyotypes
Chromosome disorders – when total number of chromosomes doesn’t = 46
Part/whole chromosome is missing or extra

21. Karyotypes
Trisomy – Having 3 chromosomes in a pair because of a nondisjunction
Nondisjunction - occurs when sister chromatids fail to separate during anaphase

22. Down syndrome ____________
TRISOMY 21, nondisjunction

23. Down syndrome (Trisomy 21)
1 in 800 births
Similar facial features
Slanted eyes
Protruding tongue

24. Turner syndrome

25. Klinefelter syndrome XXy

26. Karyotypes
What is the gender?
Any chromosomal disorders?

27. Karyotypes
What is the gender?
Any chromosomal disorders?

28. Karyotypes
What is the gender?
Any chromosomal disorders?

29. Karyotypes
What is the gender?
Any chromosomal disorders?

30. Autosomal (Body) Disorders

31. Genetic Disorders Autosomal (Body) disorders
2 Types of genetic disorders:
Autosomal (Body) disorders
Sex-linked (Gamete) Disorders
Cystic Fibrosis
Colorblindness
Sickle Cell Amenia
Hemophilia
Huntington’s Disease

32. Genetic Disorders
Cystic Fibrosis Inheritance pattern: autosomal recessive Chromosome 7 Symptoms: thick, sticky mucus in lungs

33. Leads to respiratory and digestive problems
More common in Caucasians, but affects all races
30,000 people in the USA have cystic fibrosis

34. Genetic Disorders Sickle cell Anemia
Inheritance pattern – autosomal recessive
Chromosome: 11
Symptoms – Mis-shaped red blood cells
Relationship to malaria: carriers of sickle cell are immune to malaria

35. Genetic disorders Huntington’s Disease
Inheritance pattern – autosomal dominant
Chromosome 4
Symptoms – damage to nerve cells, loss of body movement control

36. HUNTINGTON’S DISEASE loss muscle control mental
Huntington’s brain
loss
Causes progressive _____ of ________________ and ___________function
muscle control
mental
1 in 10,000 people in U.S.
have Huntington’s disease
Normal brain

37. A person with
Huntington’s disease
has a _____ chance of
passing the disorder on to
their offspring.
50%

38. Review:
Huntington’s Disease, Cystic Fibrosis and Sickle Cell are disorders of your body cells – it doesn’t matter if you are male or female
Now lets talk about disorders that are sex-linked: the chances of giving the disorder to your children are different if the child is a boy or a girl

39. Sex-linked traits Found on X chromosome, always recessive
Who can get it?  Everyone
More likely for males…they only have one X (if it’s recessive, they have no chance of hiding it)

40. Or Males ONLY HAVE ONE X They either have the They are disorder normal
DEFECTIVE
NORMAL
They either
have the
disorder
They are
normal Or

41. Females have one normal gene that works.
FEMALES HAVE TWO X CHROMOSOMES
DEFECTIVE
NORMAL
DEFECTIVE
Females have one normal gene that works.
need 2
Females __________ defective recessive
alleles to show the
disorder

42. Sex-linked traits Male Female XAY – healthy XaY – sick XAXA healthy
Females can be carriers
Genotypes:
Male
XAY – healthy
XaY – sick
Female
XAXA healthy
XAXa Carrier
XaXa -sick

43. Genetic disorders Colorblindness
Inheritance pattern – sex-linked recessive
Chromosome X
Symptoms – trouble distinguishing between some colors
8% of males; 0.5% of females

45. Genetic disorders Hemophilia
Inheritance pattern – sex-linked recessive
Chromosome X
Symptoms – blood does not clot normally

46. XH Xh Y XHY XhY XhXh XHXh Xh
How to do a sex-linked problem: Hemophilia is X-linked recessive (so hh is needed to have hemophilia)
PROBLEM: cross a carrier mom with an afflicted dad
XH Xh
XhXh
XHXh Xh Y
XHY
XhY
How many girls will have it? Boys? Who are carriers?

47. Warm Up What percentage of their children will be colorblind?
Cross a man who is colorblind with a woman who is a carrier for colorblindness. Answer the following questions:
What percentage of their children will be colorblind?
What percentage of the males are colorblind?
What percentage of the females are carriers?
What percentage of the children are not affected and are also not carriers?

48. Pedigrees
Family tree that shows the heredity of a specific trait (usually a disorder)
= male
= female

49. Pedigrees If the is filled in = someone with the trait
If the is empty = someone without the trait

50. I II 1 2
III IV

51. http://www. ikm. jmu. edu/Buttsjl/ISAT493/Hemophilia/hemophiliaeurope