MT2 Content Flashcards
How is selective permeability achieved?
- substrate-specific carrier proteins (permeases)
- Dedicated nutrient-binding proteins patrolling periplasmic space
- Membrane-spanning protein channels/pores
ABC Transporters
-powered by ATP
-found in all 3 domains of life
-gram - employ peiplasmic binding proteins
-gram + & archaea employ substrate-binding proteins on external surface of cytoplasmic membrane
2 main types of ABC Transporters
-Uptake: taking things in, critical for transporting nutrients
-Effflux: pump shit out, generally used as multidrug efflux pumps
Growth Cycle
- Growth: increase in # of cells
- Binary fission: cell division when cell doubles in size
- Septum: Partition of cells, creating 2 daughter cells
Planktonic growth
-growth as suspension
Sessile growth
-attached to surface
-can develop into biofilms
Biofilms
-forms in stages
-planktonic cells attach
-sticky matrix forms
Microbial Mats
-multilayered sheets w/ diff. organisms in each layer
Closed Culture
-limited nutrients
-also called batch culture
Bacterial Growth Curves
- Lag phase: no increase in number of living cells (takes a while to adapt)
- Log phase: exponential increase in # of living bacterial cells
- Stationary phase: plateau in # of living cells; death rate = birth rate
- Death phase: exp. decrase in living cells
Continuous Culture
-all cells in pop. achieve steady state
-chemostat constantly adds & removes equal amounts of culture medium (ensures log growth)
Biofilms
-surface attached communities
-can be constructed by 1 or multiple species
-can form on range of surfaces
-difficult to dislodge
-protect bacteria from chemicals
Biofilm development involves?
-adherence of cells to a substrate
-formation of microcolonies
-formation of complex channeled communities that generate new planktonic cells
Biofilm Life Cycle
- Attachment to monolayer by flagella
- Microcolonies
- Exopolysides (EPS) production
- Mature biofilm
- Dissolution & dispersal
Molecular constitution of biofilms
-EPS (polysaccharides in gram + and cellulose in gram -)
-proteins
-eDNA