Chapter 9 Flashcards
Transformasome
Spams cell envelope, binding protein to capture DNA from environment and proteins that from a pore
How do gram positive bacteria transform DNA?
They has a transformasome complex
Quorum sensing
Triggers competence, senses DNA, doesn’t happen in dilute populations (waste of resources)
Gram negatives don’t use ________ or ________ in transformation
Competence factors and transformasomes
What type do gram negatives use for transformation?
Type IV pilus
Conjugation
Transfer of DNA from one love bacterium to another following cell to cell contact
OriV
Replication origin used in nonconjugating cells
OriT
Replication origins used during DNA transfer
Episome
Plasmid that can exist in extra chromosomal or integrated form
HFR
High frequency recombinant
Abberant excision
Plasmids that take genes with it when it leaves (messy divorce)
Transduction
Bacteriophages carrying host DNA from one cell to another
Transducing particle
Phage that carries bacterial host DNA from one cell to another
Lambda phage
Stays dormant until activated
Restriction enzymatic cleavage
Cleaves foreign DNA (bacterial safe sex)
Modification
Protective methylation prevents host DNA so it’s not accidentally destroyed
Site specific recombination
Requires short sequence of homologous recognized by recombination enzyme
RecA independent
Generalized recombination
Needs long stretch of homology esteem cells, needs recA
RecA
Helps align homologous DNA and catalyze the exchange of strands
Transition mutation
Purine switches to other purine or same with pyrimidines
Transversion point mutation
Purine to pyrimidine or vice versa
Inversion mutation
DNA is flipped in orientation
Reversion mutation
DNA mutates back to original sequence
Missense
Wrong codon
Tautomeric shifts
Alter base pairing properties (as pair with Cs and Gs with ts)
Oxidative deamination
Removed part of molecule to make it a different base
Apurinic site
Take out whole purine
Ames test
Negative- few colonies
Positive- colonies centered around disk because it caused mutation and reversions
Tests if it’s carcinogenic
Two types of DNA repair
Error proof and error prone
Methyl mismatch repair
Error proof prevent mutation
Based on recognition of methylation pattern
Photoreactivation
Error proof
Enzyme photolyase binds to pyrimidine diner and cleaves cyclonic and ring
Nucleotide excision repair
Error proof
Endonucleoases remove path of ss DNA contained damaged bases
Base excision repair
Error proof
Cuts damaged parts from the backbone severe
SOS repair
Error prone
Last resort
Mutate or die
Insertion sequence
Target of transposase
New gene flanked by shirt inverted repeat sequences
How do IS elements transfer?2
Nonreplicative- it takes from one to give to another
Replication transposition- duplicates, then gives
Type I transposon
1 gene
Type II transposon
Multiple genes
Pathogenicity islands
Encode virulence factors
Mobile symbiosis islands
Enable a microbe to enter into symbiotic relationship
Pseudo genes
Nonfunctional genes in the process of being eliminated
