Question

List then describe the FOUR stages of the standard growth curve and then describe in some detail the major "events" of each stage. You should be able to include DNA replication, binary fission/cell division, mechanisms of genetic diversity in bacteria, sporulation, production of primary and secondary metabolites, etc

Answer 1

Growth means increase in cell size and number.It is essential for all the organism present in environment.Somes species shows fast growth and some slow, it totally depends on some biotic and abiotic factors.

When bacteria grown in nutrient rich environment, it shows fast growth .The growth of bacteria has four stages like lag phase,log phase, stationary phase and death phase.

1​​​​.Lag phase : When bacteria comes into a new medium they takes some time to adapt or adust themselves with the environment termed as LAG phase.This phase vary from species to species, depends on the nutreints presence.

In lag phase cellular metabolism rate increase,cell size increase but DNA replication does not occur ,which results into no cell MASS increase.In other word we can say that this phase is like a prepratory phase in which bacteria prepare themselves for DNA replicat and cell division.

​​​​​​2.LOG phase:This phase is also called exponential phase because in this phase bacteria grows rapidly due to presence and utilization of rich nutrient.

In this phase metabolic activity reaches to its peak results into starting of DNA replication by binary fission.In this phase cell divides rapidly and attain their maximum number.

3.Stationary phase:When the bacteria grows rapidly in log phase,they consumes all the nutrient present in the medium,then after consumption of nutreints there will be accumulation of certain waste material,production of primary and secondary metabolites which results into the decline of growth of bacteria called STATIONARY phase.

In this phase reproduction rate will be low and some bacteria move into their sporulation phase to maintain their diversity. In sporulation they conserve their genetic information.In this phase the number of live cells is equal to number of death cells.

4.Death phase:After depletion of all nutrient material in media and accumulation of primary and secondary metabolites bacteria will not able to reproduce results into their death termed as Death phase.

In this phase the number of live cells is less than dead cells means .

Diagramatic explanation:

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