Chapter 9 Flashcards
Deletions, insertions, inversions, translocations, and other changes that can affect one base pair to hundreds or thousands of base pairs
Gene mutations
Alterations of a single or a few base pairs
Point mutations
Types of gene mutation
Silent mutation
Conservatove mutation
Non-conservative mutation
Framshift mutation
Substitution of one nucleotide with a different nucleotide
Silent
Without changing the amino acid sequence
Silent
Substitutions may change the amino acid sequence
Conservative
But the replacement and the original amino acid have similar biochemical properties, e.g., leucine for valine, change will not affect protein function significantly
Conservative
Substitution of a biochemically different amino acid, e.g., proline for glutamine, which changes the biochemical nature of the protein
Non conservative
Terminates proteins prematurely when a nucleotide substitution produces a stop codon instead of an amino-acid
Nonsense
Insertion or deletion of more or efewer than three nucleotides throwing the triplet code out of frame
Frameshift
Detected from the most convenient and noninvasive specimen material, such as blood or buccal cells
Inherited mutation
Often more challenging to find because cells harboring mutations may be only a small fraction of the total specimen that consists of mostly normal cells
Somatic mutation
Under these circumstances, detection procedures must identify a single mutated gene from among thousands of normal genes
Somatic mutation
Three Broad Approaches:
- Hybridization - based methods
2 sequence ( polymerization) - based methods - Enzymatic or chemical cleavage methods
more frequently used mutation screening
SINGLE-STRAND CONFORMATION POLYMORPHISMS (SECP)
is determined by the migration of the single-stranded
conformers in polyacrylamide gels under precisely controlled denaturing and temperature conditions.
SINGLE-STRAND CONFORMATION POLYMORPHISMS (SECP)
Steps in SSCP
short,double-stranded PCR produts➡️Dilute
long ➡️Denatured followed by rapid cooling
SSCP DENATURATION OF DNA
10-10 mM NaH, 80% formamide for 5 mins at 95°c
SSCP DENATURATION IF EDTA
0.004 mM EDIA 10% formamide for 5 mins
at 55°- 60°C
the _____________________ depends on the complementary
nucleotides available for hydrogen bonding and folding
shape of the conformer