Base substitution that does not change the codon.
Base substitution that does change the codon.
Base substitution that codes for a STOP codon too early.
Base addition or deletion that affects all following codons.
one base pair is replaced with a different base pair
pyrimidine (C/T) to pyrimidine or purine (G/A) to purine
pyrimidine to purine / purine to pyrimidine
one or more extra nucleotides present
one or more nucleotides absent
occurs in absence of known mutagen
occurs in presence of known mutagen
Germ line Mutation
in reproductive cells
in nonreproductive cells
expressed in restrictive but not permissive conditions
eliminates normal function
reduces normal function
increases normal function
expressed at wrong time or in incorrect location
Removal of an adenine or guanine, Deoxyribose and purine base have a relatively unstable covalent interaction, Mammalian cell looses 10,000 purines every 20 hours
TEMPERARY Essentially the shifting of electrons
Guanine and thymine: keto to an enol/ Adenine and cytosine: amino to imino
Deamination of cytosine leads to uracil.
Uracil is not a normal component of DNA and can be recognized and removed.
Deamination of 5-methylcytosine leads to thymine.
Thymine is a normal component of DNA and is not recognized as a source of potential mutation.
Alkyl group covalently attached (CH3)
acridine orange, proflavin, ethidium bromide (used in labs as dyes and mutagens)
Flat multiple ring molecules
Interact with bases of DNA and insert between them
Insertion causes a "stretching" of the DNA duplex
DNA polymerase is "fooled" into inserting an extra base opposite an intercalated molecule
intercalating agents cause frameshifts.
Two adjacent pyrimidine bases, typically a pair of thymines, in the polynucleotide strand, between which chemical bonds have formed; the most common lesion formed in DNA by exposure to ultraviolet light.
A bacterial test for a mutagenicity; also used to screen for potential carcinogens. Used Rat live enzyme, the unknown chemical, and a histidine auxotroph type of salmonella.
Term applies to certain sequences composed of tandem repeats that show genetic instability owing to a relatively high frequency of change in the number of copies of the repeat from one generation to the next.
Reversal of covalent modifications/ Repair thymidine dimers (use enzyme, photolyase)
Base Excision Repair
A mechanism of DNA repair initiated by removal of a mismatched or damaged base from its associated deoxyribonucleotide sugar. Recognize:
uracil (NOT IN DNA)
OG (from oxidation of G)
Nucleotide Excision Repair
A mechanism of DNA repair in which nucleotides with mismatched or damaged bases are cleaved from a DNA strand and replaced using the complementary DNA strand as a template.UvrA and B scans for irregularities
UvrB,C nick region surrounding dimer
UvrD helicase unwinds region, releases strand
DNA pol fills in gap
Ligase seals repaired strand
Mismatch Repair (methyl directed)
Removal of one nucleotide from a pair that cannot properly hydrogen-bond, followed by replacement with a nucleotide that can hydrogen-bond.
Repair of damaged DNA by exchange of good for bad segments between two damaged molecules.
Translesion DNA Polymerases
Special active site with large pocket that allows for polymerase to go over the error, more likely to incorporate incorrect nucleotides
E. coli SOS response
An inducible, error-prone system for repair of DNA damage in E. coli. Enzymes are attracted to stalled replication forks.