1. Human Genetic Mutations

2. Gene Mutations Small scale: one gene is affected
Any change to the DNA sequence of a gene:
Nucleotides/Bases may be added, missing, or changed

3. Gene Mutations: 2 Types
Point Mutation
Frameshift Mutation

4. Point Mutation One base (A, T, C, or G) is substituted for another
3 Possible Consequences:
nonsense mutations: code for a stop, which can produce the wrong protein
missense mutations: code for a different amino acid
silent mutations: code for the same amino acid.
Most common!!

5. Frameshift Mutation
One or more bases (A, T, C, or G) are added or deleted
Causes: Cystic Fibrosis
Caused by:
Insertion: adding a base
Deletion: removing a base

6. Causes of Mutations spontaneous occur during DNA replication
Caused by MUTAGENS
physical, ex: radiation from UV rays, X-rays or extreme heat
or chemical (molecules that misplace base pairs or disrupt the helical shape of DNA).

7. Gene Mutations KEY IDEA: A mutated gene will make a mutated protein
Mutant proteins are trouble!
They do not go where they are supposed to go
They do not do what
they are supposed to do

8. Example: Sickle Cell Anemia
Normal Red Blood Cell
Sickle Red Blood Cell
Red blood cells shaped like a disc
Hemoglobin (protien) carries oxygen to all parts of the body
Red blood cells form an abnormal crescent shape
Hemoglobin (protein) is abnormally shaped
don't move easily through your blood vessels
form clumps and get stuck in the blood vessels

10. Example: Cystic Fibrosis (CF)
What is it?
Autosomal, recessive
disorder
Symptoms
Thick mucus in the lungs and digestive track
Constant lung infections and impaired digestion

11. Cystic Fibrosis (CF) Who gets it? Anyone Most common in Caucasians
Prevalence
1 in ~3,000 Americans has CF
1 in 23 white Americans carries the mutant allele!

12. Cause of Cystic Fibrosis (CF)
The “CFTR” gene is mutated
3 base pairs are deleted
Mutant protein is missing an amino acid and cannot fold correctly vs

13. Normal CFTR protein: Ion channel in cell membrane

14. KEY POINT #2 Mutation of a gene = Mutant protein
Dysfunctional proteins cause the symptoms of the disorder

15. Review What are the two major types of genetic mutations?
How are chromosomal aberrations and gene mutations different?
What are the 4 types of chromosomal aberrations?
What are some types of gene mutations?