1. Mutations

2. What Are Mutations? Changes in the nucleotide sequence of DNA
May occur in somatic cells, so not passed on to offspring
May occur in gametes and be passed on to offspring

3. Mutations happen regularly
Can occur during DNA replication
Chemicals & radiation can cause mutations
Many mutations are repaired by enzymes

4. Are Mutations Helpful or Harmful?
Many types of disorders (e.g. skin cancers) result from somatic mutations
Some mutations may improve an organism’s chances of survival

5. Types of Mutations

6. Chromosome Mutations Changing the structure of a chromosome
The loss or gain of part of a chromosome
Ultimately they change either a type of gene

7. Chromosome Mutations Five types exist: Deletion Inversion
Translocation
Nondisjunction
Duplication

8. Deletion Due to breakage
A piece of a chromosome is lost and not replaced

9. Angelman Syndrome
Caused by a deletion on a gene (chr.15) inherited from mother
Developmentally delayed
Overly happy and excitable

10. Inversion Chromosome segment breaks off
Segment flips around backwards and reattaches

11. Inversion

12. Duplication
Occurs when a gene sequence is repeated

13. CMT Syndrome Chr.17 duplication Inherited Weakness of foot
High arches and hammer toes are common

14. Translocation Involves two chromosomes
Part of one chromosome is transferred to another chromosome

15. Philadelphia Translocation
Part of chr.8 and chr.22 go to chr.9
Individuals develop leukemia
Philadelphia Chromosome

16. Translocation

17. Nondisjunction Failure of chromosomes to separate during meiosis
Causes gamete to have too many or too few chromosomes

19. Symptoms of Klinefelter Syndrome (XXY)

20. Gene Mutations Change in the nucleotide sequence of a gene
May only involve a single nucleotide
May be due to copying errors, chemicals, viruses 20

21. Point Mutation Change of a single nucleotide
Includes the deletion, insertion, or substitution of ONE nucleotide 21

22. Point Mutation
Sickle Cell Anemia is the result of one nucleotide substitution
Occurs in the hemoglobin gene 22

23. Frameshift Mutation Inserting or deleting one or more nucleotides
Changes the “reading frame” like changing a sentence
Proteins built incorrectly 23

24. Frameshift Mutation Original: Frame Shift (an “a” is added):
The fat cat ate the wee rat
Frame Shift (an “a” is added):
The fat caa tet hew eer at
?????????????? 24

25. Amino Acid Sequence Changed25

26. Pedigree Analysis
Assessing the genetic basis of a disease or trait from its inheritance pattern
Predicting the risk of disease in future offspring in a family (genetic counseling)