This is the period of little or no cell division so the population remains temporarily unchanged.

No apparent cell division occurs but the cells maybe growing in volume or size, synthesizing enzymes, proteins etc. and increasing in metabolic activity in preparation for the next phase.

The cells begin to divide and enter a period of growth or logarithmic increase. Cellular reproduction is most active during this period and generation time reaches a constant minimum.

Exponential growth cannot be continued forever in a batch because of the following reasons:

Growth slows down due to nutrient depletion and formation of toxic products.

In this phase, the number of new cells produced balances the number of cells that die. This results in a steady state.

It is characterized by an exponential decline or decrease in the number of viable bacteria. For a microbial cell, death means the irreversible loss of the ability to reproduce.

Factors that must be controlled during growth includes

_____ is used in forming the amino group of the amino acids of proteins.

It can be obtained from nitrate, nitrite, ammonium, amine and amino acids.

_____ is a component of many organic cell substance forming part of several coenzymes and found in the cysteinyl and methionyl side chains of proteins.

_______ in the form of phosphate is required as a component of ATP, nucleic acids and coenzymes like NAD, NADP and flavins.

_____ is found in chlorophyll molecules

____ is part of the coenzyme of the cytochromes and peroxidases

____ is/are essential for the function and integrity of ribosomes

_____ is a required constituent of gram-positive cell walls

Nutritional type of Prokaryotic cell; Energy source of photoautotrophs is ___

Nutritional Types of Prokaryotes

Energy source is inorganic compounds while carbon source is carbon dioxide

Nutritional Types of Prokaryotes;

Energy and carbon source are organic compounds

microorganisms that live in a pH of 3.0 or acidic.

microorganisms that live in a pH of 10.5 or basic.

microorganisms that live in a pH range of 6.0 to 8.0

grow best at low temperatures (15C to 20C)

grow best at 30C to 37C

grow best at 50C to 60C

grow well above the temperature of boiling water

Beyond the effects on growth rate, extremes of temperature can also inhibit the growth by _____ or kill microorganisms.

Beyond the effects on growth rate, extremes of temperature can also inhibit the growth or kill microorganisms by ______

The use of oxygen generates two toxic substances:

_______ catalyzes the reaction of the superoxide radical with hydrogen forming hydrogen peroxide and oxygen.

________ catalyzes the breakdown of hydrogen peroxide into water and oxygen.

require 21% oxygen because they possess both SOD and catalase enzymes.

require 2 to 105 of oxygen.

survive in the absence of oxygen because they lack both SOD and catalase enzymes.

can survive in the presence or absence of oxygen because they possess either SOD or catalase.

can grow in the presence of oxygen but grow best in its absence.

requires 5 to 10% of carbon dioxide, instead of oxygen.

______ are organisms requiring high salt concentration.

____ are organisms requiring high osmotic pressure.

Sources of Metabolic Energy

If the number of cells in 0 hours is 2 then, in 20 minutes is 4. What is the number of cells in 40 minutes?

Osmotic conditions: microbes tolerating NaCl are ____