Microbial Physiology and Genetics I - DNA Repair and Adaptation

Flashcards on DNA repair mechanisms, replication, and related concepts.

DNA Repair

The mechanism that repairs damaged DNA before it becomes a heritable mutation.

Error-Proof DNA Polymerase

DNA polymerases that do not introduce mutations during DNA repair.

Error-Prone DNA Polymerase

DNA polymerases that use "emergency" methods and are not accurate, potentially introducing mutations.

Semi-Conservative DNA Replication

A process where DNA replication results in two identical helices, each containing one original strand and one newly synthesized strand.

DNA Polymerase

Enzymes that catalyze the synthesis of DNA.

Methyl Mismatch Repair

A DNA repair system where many bacteria tag their parental DNA by methylating it at specific sites.

Methyl-Directed Mismatch Repair Enzymes

Enzymes (MutS, MutL, and MutH) that bind to a mismatch in DNA and loop the DNA during methyl mismatch repair.

MutH

An enzyme that cleaves the unmethylated strand containing the mutation during methyl mismatch repair.

DNA Helicase

Enzyme that unwinds the cleaved strand during methyl mismatch repair.

DNA Polymerase I (Pol I)

Enzyme that fills in the gap after the mutation is cleaved out during methyl mismatch repair.

DNA Ligase

Enzyme that seals the remaining nick after the gap is filled in during methyl mismatch repair.

Base Excision Repair (BER)

A DNA repair system where the enzyme glycosylase recognizes the wrong nucleotide and cleaves the bond connecting the damaged base.

Glycosylase

Enzyme that recognizes the wrong nucleotide and cleaves the bond connecting the damaged base during Base Excision Repair.

AP Endonuclease

Further process the cleavage AP site during Base Excision Repair.

DNA Polymerase I

DNA polymerase I will degrade the cleaved strand downstream of the AP site and at the same time synthesize in its stead a replacement strand containing the proper base during Base Excision Repair.

DNA Ligase

DNA ligase seals the remaining nick, and the repair process is complete during Base Excision Repair

Homologous Recombination (HR)

A DNA repair system that uses an intact copy of the DNA to repair a double-strand break in the damaged copy.

SOS Response

A global response to DNA damage in bacteria; involves activation of genes for DNA repair, mutagenesis, and antibiotic evasion.

DNA Polymerase V

An enzyme that sacrifices accuracy for continuity, inserting whatever nucleotide is available when encountering an undecipherable damaged base.

Non-Homologous End Joining

A DNA repair system that doesn't require homology and can be error-prone, causing the loss or addition of nucleotides at the break site.

Ku Protein

Protein involved in Non-Homologous End Joining that binds to the ends of a double-strand break and recruits LigD.

LigD

Recruited by Ku protein, Lig D is a protein with polymerase and 3′ exonuclease activities that fill in or remove single-strand overhangs, and a ligase activity that joins two double-strand breaks during Non-Homologous End Joining.

Bacteriophage

A type of virus that infects bacteria.

Lysis

The bursting of the bacterium during Bacteriophage.

Ames Test

A test used to detect potential mutagens.

Lamarck’s concept of evolution

Lamarck did not believe in extinction of species, Species are gradually transformed into other species and Innate tendency of organisms to achieve perfection

Darwin’s theory: Natural Selection

Individual organisms within a species show a wide range of variation, individuals with traits most suited to the environment are more likely to survive to breed successfully and These traits then passed on to the next generation