Types of Mutations
Thanks to Ms. Sara Dozier and Ms. Kimball for many of these slides!
Mutations•Mistakes in the nucleotide sequence in the DNA of a cell
•Caused by:
•Errors during DNA replication
•UV light
•Radiation
•Toxic chemicals
•Some viruses
•Immune system
What is a Mutant?
We are ALL Mutants!
Why Mutate?• Mutations are a natural source of variation
• Variety in a population is good!
• Variation is essential to evolution
• SOME mutations are good: help an organism survive and reproduce
• SOME mutations are bad: cause disease or death
•MOST mutations are neutral: do not help nor hurt
•Often repaired or not expressed
Do Mutations Matter?• Antibiotic resistance is due to mutations (GOOD for bacteria, BAD for us)• Tay Sachs Disease is due to a frame shift mutation (BAD for humans)• Some people are resistant to HIV infection due to a mutation in an immune cell receptor CCR5 (GOOD for those lucky ones!)
HIVHIV is a virus - it’s not considered a living thing because it needs a host cell to reproduce and make proteins
HIV affects the immune system, making it hard for an infected person to fight off other diseases
HIV has a high mutation rate, which means it’s constantly changing and evolving
This makes it very difficult to create a cure or vaccine
Point Mutation•A single base in the DNA sequence is changed to another base
•3 types of point mutations:
•Silent
•Missense
•Nonsense
Silent Mutation•Type of point mutation
•A nucleotide base changes, but the amino acid stays the sameORIGINAL DNA: TAC CGT ACG GAT AAG ACT
ORIGINAL AA: MET ALA CYS LEU PHE STOP
MUTATED AA: MET ALA CYS LEU PHE STOP
ORIGINAL RNA: AUG GCA UGC CUA UUC UGAMUTATED RNA: AUG GCA UGU CUA UUC UGA
MUTATED DNA: TAC CGT ACA GAT AAG ACT
Missense Mutation
•Type of point mutation
•A nucleotide base changes which results in an amino acid to changeORIGINAL DNA: TAC CGT ACG GAT AAG ACT
MUTATED DNA: TAC TGT ACA GAT AAG ACT
ORIGINAL AA: MET ALA CYS LEU PHE STOP
MUTATED AA: MET THR CYS LEU PHE STOP
ORIGINAL RNA: AUG GCA UGC CUA UUC UGAMUTATED RNA: AUG ACA UGC CUA UUC UGA
Nonsense Mutation
•Type of point mutation
•A nucleotide base changes which causes an early stop codonORIGINAL DNA: TAC CGT ACG GAT AAG ACT
MUTATED DNA: TAC CGT ACT GAT AAG ACT
ORIGINAL AA: MET ALA CYS LEU PHE STOP
MUTATED AA: MET ALA Stop
ORIGINAL RNA: AUG GCA UGC CUA UUC UGAMUTATED RNA: AUG GCA UGA CUA UUC UGA
Other types of Mutations
•Reading Frames
•Frameshift mutations
•Insertion of an extra nucleotide OR
•Deleting of a nucleotide
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