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PILI vs FIMBRIAE
- Fimbriae latin for thread or fiber, shorter and dense, coded on chomosome.
- Pili latin for hair or hairlike, longer and fewer. coded on plasmid (F plasmid, esp. conjugated or sex pili)
- promotes attachment to other bacteria or host.
- Biofilm formation
- important virulence factor for colonization and infection.
- Some tips of fimbria may contain lectines (sugar binding protein)
Pili consist of the protein _____.
- cell surface associations.
- Enable attaching to epithelial cells or bacteria. aggregation; build up biofilms and plaques.
- twitching movement by type IV pili, establish new microcolony
- Conjugate/sex pili (type IV; conjugation & transformation; important for developing drug resistance;virus adherence)
saturate the system w/ oligosacchride, block the bacteria before the pili's receptor binds to host cell surface sugars.
- Twitching: semi-solid surface; 1.5% agar; type IV pili
- Swimming: flagella; liquid enviroment; 0.3% agar
- Swarming: flagella and the secretion of polysaccharide slim; semisolid surfaces; 0.5% agar.
- Gliding motility: secretion of slim compound in bacteria which lack pili and flagella; semisolid surfaces.
Flagellum consist of the protein _____. Involve in ______ motility.
- swimming and swarming
- basal body:
- C ring (cytoplasmic)
- Mot: stator, using [H] gradient energy
- Fli: motor switch
- MS ring - inner membrane
- C + MS = rotor
- P ring - periplasmic; attached to peptidoglycan
- L ring - attached to LPS (not seen in G+)
- Involved in cell movement in liquid environments.
- Has a role in reaching the surface.
- Has a role in attaching to the surface.
- Could have a role in surface motility.
- Could have a role in biofilm detachment.
- The movement towards or away from an agent
Bacteria are too small to sense gradient along the length of the cell (spatially) but can sense it temporally by monitoring the environment as it moves.
Methods for Measuring Chemotaxis
endoflagella moves the cell by rotating in spirochetes
causing Lyme disease, Syphilis, periodontal disease, Trench mouth.
Gene (DNA) vs. Protein (gene product):
- tadA, tadB, tadC
- TadA, TadB, TadC
Which pairing of bases are more stable
- GC > AT
- archea has more GC
Each base pair is ___. One helical turn is ___ base pairs.
______ allows the packaging of long (circular) DNA molecule into the cell. The process is catalyzed by ______. ____ helps stabilizing _____. Each cell contains ____ copies of each gene: _____.
- nick, rotate around helix, and seal.
- Topoisomerases - DNA Gyrase (prokaryotic)
- supercoiled domains
- haploid (eukaryon has two copies: diploid)
Supercoiled DNA is located at ________, not ____.
mitochondria and chloroplasts contain their own genomes and are highly derived from ancestors of Bacteria. Mitochondria and chloroplasts were thus once free-living cells that entered Eukarya eons ago
Correlation between size of bacterium and life styles
Symbiont < Parasites < Free living bacteria
- Segments of DNA that can move from one region of DNA to another.
- Role in genetic variation. the force that drives evolution
- circular extrachromosomal genetic elements.
- Small- about 3000bp.
- Multiple copies in the cell-copy number (1-100 per/cell)
- do not duplicate at the same time with chromosome
- wide range: both G+ and G-
- narrow range: only some
- Can be obtained and lost
- Contains no essential function but may provide a selective growth advantage under certain conditions. such as:
- Antibiotic resistance- R plasmids.
- Enzymes for degradation of organic compounds.
- Virulence factors- toxins.
- Antibiotics- Bacteriocins.
- Conjugative plasmid-Carries genes for sex pili and transfer of the plasmid
RNA polymerase and _____ are involved in the initiation of transcription by ______.
- sigma factor
- promoter and initiation site
- sigma is released once transcription starts
- a collection of all the transcripts present in a given cell (rRNA, tRNA, mRNA).
- analyzing transcriptome in a cell - determine when each gene is turned on or off.
Complementary DNA cDNA
DNA synthesized from mRNA using reverse transcriptase (RNA-dependent DNA polymerase).
southern northern western
- 30S subunit contains 16S rRNA and 21 proteins
- 50S subunit contains 5S rRNA, 23S rRNA and 31 proteins.
- Shine-Dalgarno- a seq on the mRNA that is complimentary to base seq of the 16S and holds the ribosome to the mRNA. located 8 base-pairs upstream of the start codon.
- The uptake of free DNA by a bacterial cell
- involves the induction (chemically or electrically) of competence - a state in which cells are able to take up free DNA. not all cells are naturally transformable.
- • DNA binding.
- • DNA uptake.
- • Stable maintenance of the acquired DNA either by
- recombination or by DNA maintenance.
- DNA transferred from one bacterium to another by a virus (bacteriophage).
- Transduction happens through either the lytic cycle or the lysogenic cycle (integrated DNA stays dormant).
- Transfer of genetic material (plasmid or transposon) between (from a donor to a recipient) bacteria through direct cell-to-cell contact.
- - Plasmid DNA
- - Chromosome DNA
The genetic information transferred is often beneficial to the recipient cell:
- antibiotic resistance: R factor
- ability to utilize new metabolites: Dissimilation plasmids
- Conjugative (F) plasmid, genes for sex pili
- Nothing essential
how to know if integration occurred?
island of different GC content, may come from plasmids, viruses, other sources
- foreign gene and vector both w/ sticky ends, treated by restriction enzyme
- recombinate w/ the help of DNA ligase
- introduction of recombinant vector into host
- • Prokaryotes
- • Peptidoglycan cell walls
- • Binary fission
- • For energy, use organic chemicals, inorganic chemicals, or photosynthesis
- • Prokaryotic
- • Lack peptidoglycan
- • Live in extreme environments
- • Include:
- – Methanogens
- – Extreme halophiles
- – Extreme thermophiles
- • Eukaryotes
- • Chitin cell walls
- • Use organic chemicals for energy
- • Yeasts are unicellular
- • Molds and mushrooms are multicellular consisting of masses of mycelia, which are composed of filaments called hyphae
- • Eukaryotes
- • Absorb or ingest organic chemicals
- • May be mobile
- • Eukaryotes
- • Cellulose cell walls
- • Use photosynthesis for energy
- • Produce molecular oxygen and organic compounds
- Growth-Dependent Diagnostic Methods
- - Culture Organisms
- - Isolate Pure Cultures
- - Microscopy and differential staining.
- - Study Metabolism of Cultures
- - Differential growth conditions and media; Antimicrobial Drug Susceptibility
- - phage typing
- - fatty acid analysis
- Growth-Independent Diagnostic Methods
- - antibody
- - Agglutination
- - fluorescent antibody (direct)
- - Enzyme-Linked Immunosorbent Assay (ELISA): show change in color; specificity depends on the specificity of the antibody
- - PCR
- - Southern/Northern blot
- - FISH
- - rRNA: large database