1. Mendelian Inheritance Part 2
BIO 2215
Oklahoma City Community College
Dennis Anderson

2. Multiple Alleles
More than two forms of an allele exist in a population
An individual only has two of the alleles

3. Multiple Blood Alleles
A allele for making the A antigen on red blood cells
B allele for making the B antigen on red blood cells
O allele for NOT making the A or B antigen on red blood cells

4. Three alleles give four blood types
AA or AO = Type A blood
BB or BO = Type B blood
AB = Type AB blood
OO = Type O blood

5. California Court Case
1946 the California supreme court ruled that Charlie Chaplin was the biological father of a child he claimed was not his.
His defense was that the baby had type B blood. He had type A and the woman who sued him had type O (These may not be the actual blood types, but it illustrates the point)
Was the court correct?

6. O A AO OO AA, AO = Type A BB, BO = Type B AB = Type AB OO = Type O O O
The judge should take a course in zoology!

7. Mutation Change in a gene nucleotide sequence is often altered
Produce abnormal protein
Cause a disease (sickle cell anemia)
Resistance to a disease (AIDS)

8. Levels of Mutation Molecular level Chromosomal level
Deletion of nucleotides
Addition of nucleotides
Substitution of nucleotides
Chromosomal level
Change in structure
Change in number of chromosomes

9. Mutant Unusual phenotype Mutations cause mutants Normal Mutant
Has different phenotype because of a change in his DNA

10. Hemoglobin Protein molecule made of 4 globin chains
2 alpha chains with 141 amino acids
2 beta chains with 146 amino acids

11. Sickle Cell Anemia
Gene for making hemoglobin is changed from normal

12. Normal Hemoglobin Beta Chain First six amino acids
Valine
Histidine
Thre..
Leucine
Glutamic acid
Proline
CTC
Hemoglobin S Beta Chain First six amino acids
CAC
Valine
Histidine
Thre..
Leucine
Proline
One nucleotide has changed

13. Hemoglobin S
Forms long rod like molecules that stretch RBC into a sickle shape
Sickled cells obstruct circulation of blood
Allele for hemoglobin S is recessive
SS = Normal
Ss = Carrier
ss = Sickle cell anemia

14. Why is the s allele more common in Blacks than Whites?
Ancestors of Blacks lived in areas where malaria was present
Malaria parasite cannot survive on hemoglobin S
Even Ss are immune to malaria
The s allele is beneficial in an environment where malaria is present

15. Beta Globin Mutations
Over 300 different mutations!

16. Causes of Mutations Spontaneous Induced Random
About 1/100,000 chance of a gene mutating
Induced
Caused by mutagens
X-rays…break DNA
UV radiation….Thymine dimers
LSD…Break chromosomes
Cigarette smoke…damages tumor suppressor genes

17. Spontaneous Mutation
Two people of normal height have a child with dwarfism
Bacteria become resistant to antibiotics
Cold virus mutates every year
Immunity for this years cold will not protect you from next years cold
AIDS virus mutates too fast to make a conventional vaccine

18. Ultraviolet Light Causes adjacent Thymines to bond together

19. Excision Repair Enzyme Removes small section of DNAG

20. Excision Repair Removes small section of DNAG
DNA Polymerase fills in missing nucleotides

21. Xeroderma Pigmentosum
Skin blisters from sun exposure
Develop skin cancer as children
Recessive gene does not produce DNA repair enzyme

22. Sunlight Exposure Increases the Risk of Skin Cancer
DNA repair enzymes do not always fix the damage that sunlight inflicts on DNA of skin cells.
The more a person is exposed to sunlight, the greater the risk of skin cancer

23. Homologous chromosomes line up in a double file in metaphase I of meiosis

24. Homologous Pairs Separate

25. Four Gametes With Single Chromosomes

26. Fertilization

27. Nondisjunction
One pair of chromosomes fails to separate during meiosis

28. Trisomy
Zygote ends up with 3 chromosomes instead of 2 for a given chromosome pair.

29. Karyotype Picture of chromosomes
Often arranged with autosomes in descending order and sex chromosomes separate

30. Normal Male

31. Normal Female

32. Trisomy 21 Down Syndrome

33. Down Syndrome Large tongue Flat face Single crease across palm
Slanted eyes
Mental retardation
Some are not

34. Maternal Age & Down Syndrome

35. Trisomy 18 Edward Syndrome

36. Edward Syndrome Heart defects Displaced liver Abnormal hands
Low-set ears
Severe retardation
98% abort
Lifespan < 1 year

37. Trisomy 13 Patau Syndrome

38. Patau Syndrome Cleft lip and palate Extra fingers & toes Defects
polydactylism
Defects
Heart
Brain
Kidney
Most abort
Live span < 1 month

39. Klinefelter Syndrome

40. Klinefelter Syndrome Breast development Small testes Sterile
Low intelligence
Not retarded .
Klinefelter Website

41. Turner Syndrome

42. Turner Syndrome Short Not go through pruberty Produce little estrogen
Sterile
Extra skin on neck

43. Abnormal Chromosome Numbers
Aneuploidy
Missing or extra chromosome
Polyploidy
Extra set of chromosomes
Usually lethal
Common in cancer
Common in plants

44. Fetal testing can determine abnormal karyotypes

45. The End