Third base
First base
Second base
Write
a summary of the
processes of transcription
and translation

A mutation is a change in the nucleotide
sequence of DNA
–
–
Caused by errors in replication, transcription, a
cell division, or by external agents (radiation,
chemicals, & viruses)
Often cause an incorrect protein to be made. Can
lead to disease or death
Normal hemoglobin DNA
Mutant hemoglobin DNA
mRNA
mRNA
Normal hemoglobin
Sickle-cell hemoglobin
Glu
Val
 Gene
Mutations – mutations that affect only
one gene

Usually a small change that effects a single
nitrogen base or a few nitrogen bases

Point Mutation – change in a single base pair of
DNA

May have no effect because there is no change in the
amino acid
 Example
A G A
A G A
A G G

Point Mutation –

May change the entire structure of a protein by
causing a different amino acid to be substituted
 Example
A G A
A G A
C G A
 Frame
Shift – Addition or deletion of a single
nitrogen base

Changes every codon after the mutation

Usually has a negative effect on a protein
Normal gene
mRNA
Protein
Met
Lys
Phe
Gly
Ala
Lys
Phe
Ser
Ala
Base substitution
Met
Base deletion
Met
Missing
Lys
Leu
Ala
His
 Original
gene sequence:
The big red pig ate the red rag.
 What
type of mutation is shown by
The big res dpi gat eth ere dra g.
frame shift (insertion)
 What type of mutation is shown by
The big red pin ate the red rag.
point mutation (substitution)
 What type of mutation is shown by
The big rep iga tet her edr ag.
frame shift (deletion)
Structural
Rarely
changes in chromosomes
passed through generations
because the individual dies or is
sterile




Deletion – a fragment of chromosome breaks
off (either at end or an internal segment)
Duplication – a segment of chromosome occurs
more than once in the same chromosome
Inversion – a segment of chromosome is turned
180°
Translocation – movement of a chromosome
segment from 1 chromosome to another
nonhomologous chromosome
 Chromosome

=
THE SUN WAS HOT
What is the mutation…
THE SUN WAS HOT HOT
THE SUN SAW HOT
THE SUN WAH OT
 Given
the following mRNA sequence:
UUC AAG
1.
Write an example of a frameshift mutation
2.
Write an example of a point mutation that
would not affect which protein is made
3.
Write an example of a point mutation that
would cause the protein to be terminated
A genetic mutation resulted in a change in the
sequence of amino acids of a protein, but the
function of the protein was not changed. Which
statement best describes the genetic mutation?
A. It was a silent mutation that caused a change in
the DNA of the organism.
B. It was a silent mutation that caused a change in
the phenotype of the organism.
C. It was a nonsense mutation that caused a
change in the DNA of the organism.
D. It was a nonsense mutation that caused a
change in the phenotype of the organism.