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

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