Unit 3 Notes: Mutations

Unit 3 Notes: Mutations
Remember that:
• A genetic change in a population of organisms from one generation to the next
generation.
• Evolution leads to differences in populations.
• Evolution explains the origin of all of the organisms that exist today or have ever
existed.
A Refresher On The Source of Variation
Where does genetic variation come from?
1. Meiosis:
2. Sexual Reproduction:
3. Crossing over:
4. Segregation & Independent Assortment
Crossing Over
1.
2.

Genetic Variation
• Without genetic variation, some of the basic mechanisms of evolutionary change
CANNOT operate.
• Genetic Variation allows for faster adaptation and evolution than genetically
similar populations.
There are 3 primary sources of genetic variation:
1. 2. 3.
Mutations
DEFINITION:
1.
2.

There are 5 types of DNA mutations:
1.
2.
3.
4.
5.
Substitution Mutations:
DEFINITION:
Original Strand
Mutated Strand
(highlight the
mutation)
CTGGAG
1.
Example:
Sickle Cell Anemia
• Inherited disease of red blood cells
• Symptoms: pain, fatigue, breathlessness, rapid heart
rate
• Prognosis: Incurable. Some patients may live into their
50’s

Insertion Mutations:
DEFINITION:
Original Strand
CTGGAG
Mutated Strand
(highlight the
mutation)
Again...Different codon makes a different protein
Ex. Huntington’s Disease
• Huntington's disease is an inherited disorder in which some brain cells waste
away, or degenerate.
• Symptoms: Uncontrollable body movements, Dementia, Disorientation.
• Prognosis: Incurable. Death by 15-20 years old.
Deletion Mutations:
DEFINITION:
Original Strand
CTGGAG
Mutated Strand
(highlight the
mutation)
Again...Different codon makes a different protein
Cri du Chat Disease
• Cri du Chat disease is a genetic disorder caused by a missing piece of
chromosome 5.
• Symptoms: Severe mental, speech, and motor delays.
• Prognosis: Many will have normal life expectancy.

Frameshift Mutations:
DEFINITION:
Original Strand
THE FAT CAT SAT ONA RAT
Mutated Strand
(highlight the
mutation)
Again...Different codon makes a different protein
Ex. Tay-Sachs Disease (bad) or Nylonase (good)
Tay-Sachs Disease
• Inherited as a recessive gene
• A relentless deterioration of mental and physical abilities
• Usually results in death by the age of four.
Nylonase
• Some mutations are beneficial.
• Nylonase: enzyme produced by bacteria that eat nylon (a man-made product).
• Potential as an environmental clean-up agent for spills of man-made chemicals.
• But nylon is only 60 years old. Evolution in Action?
Gene Flow (aka Migration)
DEFINITION:
a. c.
b. d.

Sexual Reproduction
1.
1.
Passing on mutations
2.