Microbial Growth And Control (Lec 6-7) Flashcards
Bacterial Growth
Increasing the # of cells
Binary Fission
Cell division following enlargement of cell to 2x it’s normal size
Generation Time
Time it takes to double cell population
Peptidoglycan Biosynthesis
Production of new cell wall material
Cocci cell wall synthesis
Wall grows in opposite directions outward of the FtsZ ring
Rod-shaped cell wall biosynthesis
Wall grows at several points along the cell
Autolysins
Creates small openings in the wall which new cell material is added across
Bactoprenol
C55 alcohol that is large enough to transport sugar peptidoglycan across the cell membrane
Glycolase
- Enzyme that interacts with bactoprenol to insert cell wall precursors into the growing points
- Catalyzes glycosidic bond formation
Transpeptidation
- Final step in cell wall synthesis
- Forms peptide cross-links between glycan chains
- Inhibited by antibiotic penicillin
Peptidoglycan elongation
MreB organizes the elongasome
MreB
- forms simple cytoskeleton bands around the cell under the membrane in bacteria and probably archaea
- directs cell wall synthesis to specific points along the rod-shaped cell
Elongasome
Protein that helps elongate/form the rod shape of some bacterias
Divisome
- Squeezes and divides cell at FtsZ ring during division
FtsZ Ring
- Forms ring around center of cell the divisome can build from
- location determined by Min Proteins
- DNA replicates before ring forms
- related to tublulin (a protein responsible for cell structure and microtubules)
Exponential Growth
- growth starts slow and becomes faster
- growth of microbial population where cell numbers double in a specific time
- N = No2^n
N = final # No = initial # n = generation #
Batch Culture
- Closed-system of microbial culture with fixed volume
- Lag phase, Exponential phase, Stationary phase, Death phase
Lag phase
- To keep culture from dying keep in this phase of NO GROWTH
- freeze or dehydrate colony
- Time between inoculation of culture and beginning of growth
Why do Cells have to Die?
2nd Thermo law: energy becomes more disorganized
Exponential phase
Cells in this phase are typically healthiest
Stationary Phase
Cell population growth is zero
Death phase
If incubation continues after stationary phase the cells will die