1. DNA/GENE MUTATIONS

2. DNA/Gene Mutations Protein synthesis does encounter errors
Errors in final sequence of amino acids can be traced to errors in the original strand of DNA
Can effect the primary protein structure and ultimately the final shape and function of the protein
Two types: point mutations and frameshift mutations

3. Lets see what happens! Look at A and locate the substitution
Transcribe that part of the gene into the codon it will code for.
What amino acid should be there normally? What amino acid is there now?

4. Point Mutations Involve the substitution of one nucleotide for another
Three types of substitution:
Silent mutation
Nonsense mutation
Missense mutation
Effects vary from going unnoticed to completely changing shape of final protein

5. Silent Mutation NORMAL STRAND OF DNA: T A C T T C G A C G T G A C T
SUBSTITUTED BASE PAIR:
T A C T T T G A C G T G A C T
In normal strand: TTC 
In substituted strand: TTT 
Same amino acid, so there is no change in protein structure
DNA mRNA Amino Acid
AAG = lysine
DNA mRNA Amino Acid
AAA = lysine

6. Nonsense Mutation T A C T T C G A C G T G A C T
NORMAL STRAND OF DNA:
T A C T T C G A C G T G A C T
SUBSTITUTED BASE PAIR:
T A C A T C G A C G T G A C T
In normal strand: TTC 
In substituted strand: ATC 
Substituted base codes for a stop codon which can have disasterous effects because the protein isn’t finished
DNA mRNA Amino Acid
AAG = lysine
DNA mRNA Amino Acid
UAG = stop

7. Missense Mutation NORMAL STRAND OF DNA: T A C T T C G A C G T G A C T
SUBSTITUTED BASE PAIR:
T A C T C C G A C G T G A C T
In normal strand: TTC 
In substituted strand: TCC 
Different amino acid, so there is a change in protein structure
DNA mRNA Amino Acid
AAG = lysine
DNA mRNA Amino Acid
AGG = arginine

8. Frameshift Mutations
Caused by either the addition or removal of one or more nucleotides in the original strand of DNA
Two types:
Insertion
Deletion
Called frameshift because the addition or removal shifts the “frame” that is read for the amino acid codes

9. Insertion NORMAL STRAND OF DNA: T A C T T C G A C G T G A C T
T A C TT C C G A C G T G A C T
By inserting one base, the entire DNA strand is read differently and can result in a different final protein shape & function C

10. Deletion NORMAL STRAND OF DNA: T A C T T C G A C G T G A C T DELETION:
T A C T T C G AG TG A C T
By deleting one base, the entire DNA strand is read differently and can result in a different final protein shape & function C