BIOL 2460 Chapter 9: Microbial Growth Graded A+

BIOL 2460 Chapter 9: Microbial Growth Graded A+ Most common form of bacterial reproduction Binary fission 4 Basic Steps of Binary Fission 1. Growth of cell size and increase in cell components 2. Replication of DNA/chromosomes 3. Division of cytoplasm (cytokinesis) 4. Septum formation and division of daughter cells Cytokinesis is directed by the ___________ protein. FtsZ Where is the Z ring assembled during binary fission? On the cytoplasmic membrane Divisome activates the production of __________________ and ____________. Peptidoglycan; septum Generation Time Also known as doubling time; the time it takes to double the bacterial population (or one round of binary fission). Generation Time for E. Coli 20 minutes Generation time for B. subtilis 120 minutes Generation time for M. tuberculosis 15-20 hours Generation time for S. aureus 30 minutes Bacterial population size calculation Nn=N02n The Z ring is anchored by what? FtsZ binding proteins; also helps define the division plane between daughter cells. Nn is what? The number of cells at generation n. n is what? The number of generations. N0 is what? The initial number of cells. Growth curve Microorganisms grown in closed culture, in which no nutrients are added and waste is not removed, follow a reproducible growth pattern. Culture Density The number of cells per unit volume. Within a closed culture, it can also refer to a measure of the number of cells in the population. Phases of the Growth Curve 1. Lag phase 2. Log phase 3. Stationary phase 4. Death phase Lag Phase Period where inoculum are gearing up for the next phase of growth; the number of cells doesn't change, however, they grow larger and are metabolically active. If any cells were damaged during the transfer, they will be repaired during this phase. Inoculum Microbes that are introduced into a culture