1. Mutations that happen during Transcription and Translation

2. What happens if there is a mistake (mutation) in the DNA code?
Possibly proteins won’t be made or are made improperly.
If the mutations occur in the gametes, the offspring’s DNA will be affected positively, negatively, or neutrally.
What can cause a mutation?
Replication error
Transcription/translation error
Cell division error
Chemical agents (mutagens)
Spontaneous changes

3. Point mutation
A point mutation is a change in a single base pair in DNA.
A change in a single nitrogenous base can change the entire structure of a protein because a change in a single amino acid can affect the shape of the protein.

5. Point mutations
May change the amino acid code if the mutations occurs in the right place in the code.
mRNA
Normal
Protein
Stop
Replace G with A
Point mutation
mRNA
Protein
Stop

6. Frameshift mutations Losing or gaining a single nucleotide base
This mutation would cause nearly every amino acid in the protein after the deletion to be changed
Deletion of U
mRNA
Protein

7. Chromosomal mutations
When a part of a chromosome is left out, a deletion occurs
When part of a chromatid breaks off and attaches to its sister chromatid, an insertion occurs.
A B C D E F G H
A B C E F G H
Deletion
A B C D E F G H
A B C B C D E F G H
Insertion

8. Changes to the chromosome
When part of a chromosome breaks off and reattaches backwards, an inversion occurs.
When part of one chromosome breaks off and is added to a different chromosome, a translocation occurs.
A B C D E F G H
A D C B E F G H
Inversion A B C D E F G H W X A B C D E F G H W X Y Z Y Z
Translocation

9. nondisjunction
failure either of two homologous chromosomes to pass to separate cells during the first meiotic division

11. Repairing DNA
Enzymes proofread the DNA and replace incorrect nucleotides with correct nucleotides.
The greater the exposure to a mutagen such as UV light, the more likely is the chance that a mistake will not be corrected.