Bacterial Genome Flashcards
What is a nuceloid?
composed of a single chromosome of circular DS DNA
What are plasmids?
- usually circular
- replicate independently of nucleoid
What do plasmids usually code for?
virulence factors or antibiotic resistance genes
What are operons?
genes that are transcribed together
What is a lac operon?
codes for 3 genes that help bacteria take up and metabolize lactose
What prevents the polymerase form binding to the promoter?
repressor
What prevents the repressor from working?
allolactose
What are the characteristics of pathogenicity islands?
- code for virulence factors
- present in genome of pathogenic bacteria
- different nucleotide & codon structure
- include mobility genes -> transposases & integrases
What is transformation?
bacteria pick up bacteria from the environment
What is transduction?
bacteriophage-mediated info transfer
What are the 2 types of transduction?
- specialized -> only transfers genes adjacent to site of integration
- generalized -> random excision & packaging of genes
What is conjgation?
genetic material is transferred via pili or physical contact
What is the cause of lysis of infected bacteria?
lytic phages
What are lysogenic phages?
integrate into host DNA
What is a toxin coded for by a lysogenic phage?
diphtheria
What are transposons?
- mobile geentic elements in bacterial genome
- can move within chromosome, b/w plasmids & chromosomes
- complex ones can code for antibiotic resistance
How can antibiotic resistance be developed?
from over - prescription
What is the highly antibiotic resistant bacteria?
methicillin resistance staph. aureus
Why does beta-lactam resistance occur?
- mutations in penicillin binding protein
- mutations in porins
- beta-lactamase -> in periplasm of gram - bacteria or outside gram + bacteria
How does culture work to detect a bacterial infection?
- isolation & identification of bacteria from diseases tissues
- aka “gold standard”
How can you diagnose a bacterial infection?
- identify/isolate an organism/part of an organism -> culture, swab test, PCR
- identify evidence of immune response to infection -> ELISA
What are the types of media for bacteria?
- solid media -> agar plates
- liquid media -> used in bloodculture bottles
- selective media -> inhibits unwanted bacteris for culturing nonsterile specimens
- differential -> biochemically differenciates specific bacteria
- cell culture -> obligate intracellular bacteria
What is the best type of stain to identify bacteria?
gram
What are the steps of gram staining?
- crystal violet
- potassium ionide -> fixation
- decolorizer -> alcohol
- safarin red -> counterstain
* gram + -> purple
* gram - -> red/pink
