1. Genetic Mutations
Mutation: any mistake, or
change, in DNA sequence

2. Types of mutations:
• Point Mutations
• Frameshift Mutations
• Chromosomal Mutations

3. Point Mutations
• Changes in a single
base pair in DNA
• Errors caused by
point mutations
don’t usually
interfere much with
protein function;
however, they CAN
be disastrous.
Example:
Normal:
THE DOG BIT THE
CAT
Mutated:
THE DOG BIT THE
CAR

4. Example
Normal
AUG UUU GGC GCA UUG UAA
Met Phe Gly Ala Leu Stop
Mutated
AUG UUU AGC GCA UUG UAA
Met Phe Ser Ala Leu Stop

5. Frameshift Mutations
• Mutations in which a single base is
added or deleted from DNA
• Adding/deleting one base changes
every amino acid in the protein after.
• Proteins produced seldom function
properly

6. Example
Normal
AUG UUU GGC GCA UUG UAA
Met Phe Gly Ala Leu Stop
Mutated
AUG UUG GCG CAU UGA AA
Met Leu Ala His Cys

7. Chromosomal Mutations
Types:
1. Deletions: part of chromosome is left out
2. Insertions: part of a chromosome is
broken off and attaches to the sister
chromatid
3. Inversions: part of a chromosome breaks
out and is reinserted backwards
4. Translocations: part of one chromosome
breaks off and adds to a different
chromosome

8. Chromosomal Mutations (con’t)
• Nondisjunction: chromosomes fail to
separate properly during meiosis
– Trisomy: extra chromosome
• Down Syndrome
– Triploidy: 3 sets of chromosomes
• Banana plants
– Monosomy: lack a chromosome

9. Causes of Genetic Mutations
Spontaneous
Mutations
Mutations that occur
randomly for no
reason…
Environmental Causes
Environmental agents
X-rays
UV light
Radiation
Certain chemicals

10. Genetic Disorders

11. Cystic Fibrosis
• Caused by recessive genes on pair 7
• Causes thick mucus to form in the
respiratory and GI tracts
• Mucus clogs lungs
• Drugs administered to relieve
symptoms
• Exclusively among Caucasians

12. Osteogenesis imperfecta
• “Imperfect Bone Formation”
• Brittle bones
• Samuel L. Jackson portrayed a
character suffering from this in
Unbreakable

13. Multiple Neurofibromastosis
• Inherited
• “Elephant Man Disease”
• Multiple benign tumors that form in
skin (disfiguring)

14. Klinefelter Syndrome
• Nondisjunction of sex chromosomes
• Males have XXY sex chromosomes
• Causes long legs, enlarged breasts,
low intelligence, small testes, sterility,
and chronic pulmonary disease

15. Twin-to-Twin Transfusion
Syndrome
• A placental abnormality, which causes
disproportionate blood, transfers
between twins.
• One twin receives too much blood and
the other does not receive enough

16. Fragile X Syndrome
• Turns off a gene that develops nerve
connections to the brain
• Causes mental retardation and
autistic-like behaviors
• No cure
Fragile X Website

17. Tay-Sachs Disease
• Disorder of the central nervous system
• Child develops symptoms after birth:
diminished brain function and seizures
• Children die by the age of 5