Molecular Basis of Mutation Flashcards
Ada enzyme
E. coli enzyme that is involved in the direct repair of alkylation mutations
AP endonuclease
Enzyme involved in base excision repair
DNA glycosylase
Enzyme that cleaves the \beta-N-glycosidic bond between a
base and the sugar component of a nucleotide as part of the base excision and mismatch repair processes
DNA photolyase
Bacterial enzyme involved in repair of base dimers
DNA repair
Biochemical processes that correct mutations arising from replication errors & effects of mutagenic agents
Excision repair
DNA repair process that corrects various types of DNA damage by excising & re-synthesizing a region of polynucleotide
MGMT
Enzyme involved in direct repair of alkylation mutations
Mismatch repair
DNA repair process that corrects mismatched nucleotide pairs by replacing incorrect nucleotide in daughter polynucleotide
Nonhomologous end-joining
Name for double-strand break repair process
5-bromouracil (5-bU)
Base analog that can cause mutations by replacing T in a DNA
(6–4) lesion
Dimer between two adjacent pyrimidine bases in a polynucleotide,
formed by ultraviolet irradiation
Alkylating agent
Mutagen that acts by adding alkyl groups to nucleotide bases.
AP (apurinic/apyrimidinic) site
Position in DNA where base component of nucleotide is missing
Base analog
Compound whose structural similarity to a base in DNA enables it to act as a mutagen
Baseless site
Position in DNA where base component of nucleotide is missing
Cyclobutyl dimer
Dimer between two adjacent pyrimidine bases in a polynucleotide, formed by UV irridation
Deaminating agent
Mutagen that acts by removi
Why is DNA repair important?
Preserving composition of the genome as DNA is constantly being damaged
Alagille syndrome
Type of haploinsufficiency on gene for CD339 protein. Causes heart and liver problems.
CD339 protein
Involved in cell to cell signalling during embryo development.
Mutation on one causes alagille syndrome
Deletion mutation
Mutation caused by deletion of 1 or more base pairs from a DNA sequence
Frameshift mutation
Due to insertion/deletion of a base pairs changing frame of translation
Insertion mutation
Mutation that arises by insertion of 1 or more base pairs into a DNA sequence
Inversion
Mutation involving excision of a portion of DNA followed by reinsertion in same place but in reverse orientation
Nonsense mutation
Alteration in nucletide sequence that changes triplet coding for amino acid into a termination codon
nonsynonymous mutation
Conversion of codon for 1 amino acid into a codon for a 2nd amino acid
Point mutation
Due to single base pair change in DNA
Readthrough mutation
Change of stop codon into amino acid codon, so readthrough
Second site reversion
Second mutation that reverses effect of previous mutation in same gene without restoring original nucleotide sequence
Silent mutation
Change in DNA sequence with no effect on expression/functioning of gene/gene product
Synonymous mutation
Change of codon into second codon that specifies same amino acid
Transition
Point mutation that replaces a base with same type of base (purine/pyramidine)
Transversion
Point mutation involving purine replaced by pyramidine or vice versa
Aneuploid
Diploid chromosome set missing one chromosome
Carrier
Individual who is heterozygotic for an inherited disease, but does not show phenotype due to normal gene masking effects of mutated gene
Haploinsufficiency
Inactivation of 1 of a pair of gene resulting in change of phenotype of mutant organism
Monosomy
Presence of single copy of pair of chromosomes in normally diploid nucleus
Philadelphia chromosome
Abnormal chromosome due to translocation between chromosomes 9 and 22, a common cause of chronic myeloid leukaemia.
Trisomy
Presence of 3 copies of a chromosome in a nucleus that is otherwise diploid.
Direct repair
Enzyme comes in and directly repairs damaged DNA
Excision repair
Can repair UV damage, etc. Area around damage is removed and replaced by resynthesized DNA
Mismatch repair
Can repair base pair mistakes, etc. Area around damage is removed and replaced by resynthesized DNA
Nonhomologous end joining
Clear cut in DNA causing strands to come part. due to radiation or chemicals.
ADA enzyme
Enzyme in E.Coli which directly repairs DNA damaged by alkylation in position 4 of T and position 6 of G
MGMT enzyme
Enzyme in humans, which directly repairs DNA damaged by alkylation at position 6 of G
Molecular cloning
Cutting, joining and propagating recombinant DNA
True or False? Factor Xa is a human clotting factor of great therapeutic value to those who suffer from clotting disorders. To Maintain its biological activity it must be glycosylated (sugar groups must be added). It can be manufactured at high volume using bacteria as host.
False
The protein requires post-translational modification which cannot be done by bacterial hosts therefore the protein must be made by over-expressing in mammalian cells.
Ligation
Joining of two DNA strands or other molecules by a phosphate ester linkage.
Non-coding DNA
Introns
Spacer DNA
Regulatory DNA
Repetitive DNA sequences
