1. Mutations
(Section 17-5)
Now, that you know how gene expression works, let’s see how changes in the gene affect how the protein is made.

2. Mutations - changes in DNA
Small scale (genes) , large scale (chromosomes)
Basic types:
Substitutions (point mutations)
Insertions
Deletions
Possible resulting effects from a mutation:
Silent mutation
Missense mutation
Nonsense mutation
Frameshift mutation

3. Substitutions Single nucleotide change. Possible results:
Silent mutation
no amino acid change
redundancy in code
Missense mutaion
change amino acid
Changes the final protein
Nonsense mutation
change to stop codon
Stopping prematurely

4. Point mutation leads to Sickle cell anemia
What kind of mutation?

5. Insertions or Deletions
Adding a nucleotide
Deleting a nucleotide
Results:
Frameshift mutation – a change every amino acid from where the mutation occurred
Where would this mutation cause the most change: beginning or end of gene?

6. What’s the value of mutations?

7. The dipeptide that will form will be
A part of an mRNA molecule with the following sequence is being read by a ribosome: 5' CCG-ACG 3' (mRNA). The following activated transfer RNA molecules are available. Two of them can correctly match the mRNA so that a dipeptide can form.
tRNA Anticodon
Amino Acid
GGC
Proline
CGU
Alanine
UGC
Threonine
CCG
Glycine
ACG
Cysteine
CGG
The dipeptide that will form will be
cysteine-alanine.
proline-threonine.
glycine-cysteine.
alanine-alanine.
threonine-glycine.