Biomedical Engineering Reference
In-Depth Information
Normal (wildtype) gene
3
DNA template stand
TACTTCAAACCGATT
5
ATGAAGTTTGGCTAA
mRNA
Protein
AUGAAGUUUGGCUAA
5
Met
Lys
Phe
Gly
Stop
Carboxyl end
Animo end
Base pair substitution
Silent: no effect on amino acid sequence
GGC and GGU both code for GLY
Base pair deletion
Frameshift causing missense
Leu in place of Phe
A replaces G
A deleted
A
3
TACTTCAAACCAATT
ATGAAGTTTGGTTAA
TUCT TCUUUCCUUT T
3
TACTTCAACCGA
TT
ATGAAGTTGGCTAA
5
5
U deleted
U for C
5
AUGAAGUUGGCUAA
5
AUGAAGUUUGGUUAA
Leu
Ala
Met
Lys
Lys
Stop
Met
Phe
Gly
Stop
Base pair insertion
Missense Ser in place of Gly
T replaces C
Frameshift causing immediate stop codon
A inserted into DNA strand
3
TACTTCAAATCGATT
ATGAAGT T TAGCTAA
5
3
5
TACATTCAAACCGATT
ATGTAAGTTTGGCTA
A
A for G
Extra U
5
AUGAAGUUUAGCUAA
Phe
Met
Lys
Ser
Stop
Base pair substitution
Nonsense: create stop colon
5
AUGUAAGUUUGGCUAA
Met
A replaces T
Stop
3
TACATCAAACCGATT
ATGTAGTTTGGCTAA
5
Insertion or delection of 3 nucleotides
no extensive frameshift but Phe in place of Lys
U for A
3 Bases deleted
T
T
C
3
5
T
AAACCGATT
ATGTTTGGCTAA
AC
5
AUGUAGUUUGGCUAA
Met
Stop
3 Bases deleted
A
A
G
AUGUUUGGCUAA
5
Met
Phe
Gly
Stop
7. 3
Types of point mutations - silent, nonsense, missense and
mutations due to a frame-shift reading. (Image created by Edward
Rodriguez, St Peter's University, Art Department, Graphic Arts,
Jersey City, NJ.)
alteration to protein structure and function. It may seem remarkable that
just one nucleotide change in the DNA can result in the many clinical fea-
tures of this disease that include severe anemia, but the replacement of glu-
tamic acid by valine results in a non-polar amino acid in the place of an acidic
one. This single alteration results in a beta hemoglobin tetramer, which on
deoxidation can form aggregate arrays that are almost crystalline in nature
