microbiology exam 2
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microbiology exam 2
microbial metabolism, growth and control of microbial growth
the sum of all chemical reactions with a living organism.
(how they grow)
Results in the breakdown of more complex organic compounds into simpler substances.(break down)
: Protiens into amino acids ( releases ATP)
Result in chemical reactions in which simpler substances are combines to form more complex molecules.(build up)
: Amino acids into protiens ( requires ATP)
proteins produced by living cells.
end in -ase
speeds up chemical reaction
3 dimensional shape.
factors that influence enzymatic activity. (2)
The higher the temperature, the higher rate of chemical reaction. ( but not too high)
there is an optimal pH
The end product of a metabolic pathway inhibits an enzyme's activity early in the pathway
a series of chemical reactions which store wnergy on and release energy.
to get from A-F, need 5 enzymes
a series of chemical reactions which result in an inorganic molecule acts as the final electron acceptor.
inorganic= no carbon
final electron acceptor is oxygen
final electron acceptor is inorganic molecule other than oxygen ( NH3)
chemical reaction which splits the 6 carbon molecule of glucose into 2 molecules of pyruvic acid
-A series of chemical reactions with an inorganic molecule as the final electron acceptor.
-does not require oxygen
-real eases energy from sugar and amino acids
Time required for a cell to divide and its population to therefore double
phases of microbial growth (4)
1. Lag phase
2. Log ( Exponential) phase
3. Stationary phase
4. Death phase
no increase in the number of bacteria. little or no change in the number of cells. can last from an hour to several days
Log phase (exponential)
enponential increase cells begin to divide and enter a period of growth or logarithmic increase.
- cell reproduction is most active
- generation time reaches constant minimum
- cells become visible
total number remains constant, the growth rate slows, death and reproduction of cell is neutral and population stabilizes.
- waste products that are toxic accumulate
- certain required nutrients are exhausted.
-changes in pH and temp.
exponential decreases, the number of deaths exceeds the number of new cells formed.
Requirements for cell growth (2)
-sources of carbon and nitrogen
-organic growth factors
found in the arctic and in the ocean
( fungus, bacteria, mold)
usually with an optimum growth temp between 25 and 40 , is the most common type of microbe.
Thermophiles ( hot)
optimum growth between 50-50C. found in hot springs
require oxygen to live. growth on top of test tube sample.
unable to use molecular oxygen for energy, most are harmed by it. growth is at the bottom of the test tube sample.
use oxygen when it is present but are able to continue growth by using fermentation or anaerobic respiration when oxygen is not available. growth is all over the test tube sample.
grow only on oxygen concentrations lower than those of air. growth is just below the surface of the test tube sample.
culture media requirments (4)
right nutrients for that organism
sufficient moisture, oxygen, properly adjusted pH
sterile( no living microorganisms)
incubationat correct temp for optimal growth
chemically defined meduim
exact chemical composition is known
exact chemical composition varies slightly from batch to batch ( made from nutrients such as yeast, beef, plants)
has selected antimicrobial substances ( dyes or chemicals) which suppress the growth of unwanted bacteria and encourage the growth of the desired microbes.