1. Mutations and other genetic issues
Genetics Unit

2. Mutations Changes in the genetic material.
Any deviation from the normal chromosomal compliment
Two types:
Spontaneous mutations-occur randomly; no cause can be determined
Induced mutations are caused by some traceable artificial factor: exposure to chemicals, alcohol, drugs, radiation

3. Mutations
Mutations that produce changes in a single gene are gene mutations.
Mutations that produce changes in a whole chromosome are chromosomal mutations.

4. Gene Mutations
Point mutation-change in one or just a few nucleotides. So named because it occurs at a single point.
Substitutions
Deletions
Insertions

5. Gene Mutations
Frameshift mutation—shift the reading frame of the genetic code
Can alter a protein so much that it can’t perform its job.

6. Chromosomal Mutations
Involve a change in the number or structure of the chromosome
Some change the location of some genes on the chromosome
Some may change the number of copies of some genes.

7. Chromosomal Mutations
Four main types of mutations:
Deletion
Duplication
Inversion
translocation

8. Deletion The permanent loss of a segment of chromosome
Can be found anywhere on the chromosome
Can be caused by heat, radiation, viruses, chemicals, errors

9. Deletion

10. Duplication Doubles a segment of chromosome Can be fatal
Can be caused by uneven crossing over during meiosis or replication error before meiosis

11. Duplication

12. Causes of abnormalities
Nondisjunction
The failure of the chromosome pairs to separate during Meiosis I or Meiosis II
Result will be a zygote with too many or too few chromosomes
Two types: Primary and secondary nondisjunction

13. Primary Nondisjunction

14. Secondary Nondisjunction

15. Types of Genetics Tests
When trying to determine a genetic problem, we can use non-invasive tests such as
Pedigrees
Karyotypes

16. Pedigrees
A pedigree follows a specific trait through several generations
Resembling a type of map, the pedigree uses symbols to represent certain elements

17. Pedigree key

18. Pedigree

19. Karyotypes A photographic inventory of an individual’s chromosomes
Can show the individual’s gender and any abnormalities in chromosome number or structure

20. Karyotypes

21. Karyotypes

22. Amniocentesis
An invasive test that obtains amniotic fluid surrounding the fetus using a needle

23. Amniocentesis Pros and Cons
Able to determine fetus’ gender and/or any abnormalities
Can’t be done before 16th week of pregnancy
Can cause infection to mother and/or fetus
Can cause premature delivery and birth

24. Chorionic Villus Sampling (CVS)

25. CVS Pros and Cons
Can determine fetus gender and any genetic abnormalities
Can be done after 10 weeks
Can cause leakage of amniotic fluid
Can cause premature labor and delivery

26. Recessive Disorders Must be inherited from BOTH parents
Autosomal recessive disorders (non-sex cells)
Tay-Sachs
PKU
Cystic fibrosis

27. Recessive Disorders
Tay-Sachs—lipid accumulation in the brain; mental deficiency; blindness, death in early childhood
PKU-phenylketonuria—accumulation of phenylalanine in tissues; lack of normal skin pigment; mental retardation
Cystic fibrosis—excess mucus in lungs, digestive tract, liver; increased susceptibility to infections; often die young

28. Dominant Disorders
Can get the disorder by inheriting only one dominant allele
Huntington’s disease
Achondroplasia

29. Dominant Disorders Huntington’s Disease Achondroplasia
Mental deterioration and uncontrollable movements
Doesn’t appear until middle age
Achondroplasia
One form of dwarfism

30. Sex Linked Disorders
Is there a pattern of inheritance for genes located on the X or Y chromosome? YES especially on the X
Many times it is male children that inherit these disorders from their mothers because They inherit their X from their mom’s
Many sex linked genes are on the X
Colorblindness
Hemophilia
Duchenne Muscular Dystrophy

31. Sex Linked Disorders Colorblindness Most often found in males
Females have to inherit from both parents
1 in 100 females
Most common is red-green colorblindness

32. Sex Linked Disorders Hemophilia
Two genes on the X chromosome control blood clotting
Many times it is male children that inherit this from their mom’s X chromosome
1 in 10,000 males
A bleeding disorder; can cause death in severe cases

33. Sex Linked Disorders Duchenne Muscular Dystrophy 1 in 3000 males
Progressive weakening and loss of skeletal muscle
Caused by defective version of gene that codes for a muscle protein

34. Genetic Disorders Trisomy Downs Syndrome (extra chromosome 21)
Edwards Syndrome (extra chromosome 18)
Patau Syndrome(extra chromosome 13)

35. Downs Syndrome (Trisomy 21)

36. Edwards Syndrome (Trisomy 18)

37. Patau Syndrome (Trisomy 13)

38. Turner’s Syndrome

39. Turner’s Karyotype

40. Klinefelter’s Syndrome