Lesson 3 Flashcards
Slimy matrix made up of various polymers, depending on the microbes. Also called extracellular polymeric substances or extracellular matrix
Biofilm
Stages of Biofilm Formation
- Substratum preconditioning by ambient molecules
- Cell deposition
- Cell adsorption
- Desorption
- Cell-to-cell signaling and onset of exopolymer production
- Connective and diffusive transport of CO2
- Replication and growth
- Secretion of polysaccharide matrix
- Detachment, erosion, and sloughing
Related to tubulin, attaches to the ring around the center of the cell
FtsZ protein
Anchor that connects FtsZ ring to the cells membrane and stabilizes it
ZipA
Related to actin, helps to connect the FtsZ ring to the cells membrane membrane and recruits other divisome protein
FtsA
Forms helical spirals
MreB
Responsible for vibroid shape
Crescentin
Filament that properly positions the septum in the middle of the cell in E coli
MinCDE
Explain the Staniera life cycle
The baeocyte begins to grow, forming vegetative cell up to 30 um.
DNA is replicated over and over, and the cel produces an extracellular matrix.
The veg cell eventually transitions into reproductive phase where it undergoes rapid succession of cytoplasmic fission to produce dozens of baeocytes.
The extracellular matrix opens releasing the baeocytes
Explain the reproduction in Planctomyces
Budding
Explain the reproduction of Epulopiscium
Z rings are placed at both poles
Division formas a large mother cell and two offspring cells
Smaller cells contain DNA and become fully engulfed by the mother cell
Internal offspring grow within thy cytoplasm of the mother cell
Once offspring development is complete the mother cell dies and releases the offspring
Seemingly “growth”; cells dormant but physiologically active
Lag phase
Most intense phase of cell division, cell nearly uniform in chemical composition and physiological characteristics
Log or Exponential Phase
No net increase or decrease in cell number, slow metabolic activity, excessive accumulation of waste, depletion of nutrients
Stationary phase
Last phase of microbial growth
Death phase
Examples of direct method of counting
Petroff-Hausser counting chamber (Haemocytometer)
Electronic particle counter (Coulter counter)
Slide with known are (Breed count)
Examples of indirect method of counting
Plating techniques
Membrane filter method
Means maintaining microbes continually in the log phase; achieved by simultaneously removing waste products and adding new nutrients to the system in a controlled manner
Continuous culture
Formula for microbial growth
Nf= (N0) 2n
Formula for finding the number of generations
n= log Nf - log N0/ log 2
