1. Mutations

2. What is a mutation?
Changes in the DNA sequence that affect genetic information.

3. Gene Mutations Result from changes in a single gene. 3 Types:
Substitution
Insertion (Frame-shift)
Deletion (Frame-shift)

4. Point Mutations Substitution One nucleotide replaces another.
Usually changes one amino acid in the sequence of the protein.
Ex: sickle cell anemia

5. Point Mutation (Substitution)

6. Frame Shift Mutations Insertion/Deletion
Insertion - the addition of a nucleotide.
Deletion - the removal of a nucleotide.
Bases are still read in groups of three (codons).
Changes many amino acids in the sequence of the protein

7. Frame Shift Mutation (Insertion)

8. Frame Shift Mutation (Deletion)

9. Which would you rather have?

10. What Causes Mutations?
May occur spontaneously during cell division/meiosis.
X-rays
Asbestos
Insecticides
UV light
Radioactive substances

11. How Are Mutations Passed On?
The mutation must happen in a sex cell (gamete).

12. Chromosomal Mutations
Involve changes in whole chromosomes.
chromosomal mutations
5 types:
1. Translocation
2. Duplication
3. Deletion
4. Inversion
5. Nondisjunction

13. Chromosomal Mutations Deletion, Inversion, Translocation, Duplication

14. Chromosomal Mutations

15. Nondisjunction
An error that occurs during meiosis in which homologous chromosomes fail to separate properly.
One gamete may receive two of the same type of chromosome and another gamete receives no copy.
Ex- down syndrome

18. Down Syndrome (Trisomy 21)
Trisomy: having three copies of one chromosome.
Down Syndrome is caused by a trisomy on the 21st chromosome.
Likelihood of this disorder increases with the increasing age of the mother.

19. Age of Mother vs. Down Syndrome

20. Ways to Detect Genetic Disorders
Karyotyping- prepared enlarged photograph showing paired homologous chromosomes from a cell.
May show chromosomal abnormalities such as an extra or missing chromosome.

24. Testing for Down Syndrome
What are your thoughts on Down Syndrome testing? Would could the mother do?

25. Medical Genetic Research
Generates knowledge used to design ways of diagnosing, preventing, treating, controlling, or curing diseases of plants and animals.

26. Genetic Counseling
Discussions between physician and the family which may include inheritance patterns, prediction of genetic disorders, and family planning.
Screening
Karyotyping
Amniocentesis

27. Screening
Chemical analysis of body fluids such as blood and urine. Analysis may indicate the presence of chemicals associated with genetically-related disorders.

28. Amniocentesis
Involves the removal of amniotic fluid for chemical analysis.
This technique can show the chromosome content of the cells of the embryo.

29. Amniocentesis

30. Genetic Disorders
PKU (Phenylketonuria): individuals lack the enzyme that is needed to break down phenylalanine.
If a newborn has PKU, phenylalanine may build up in the tissues during the child’s first years of life and cause severe mental retardation.

31. Genetic Disorders: PKU

32. Genetic Disorders
Tay-Sachs Disease: lipid accumulation in the brain cells, mental deficiency, blindness, death in early childhood.