Explain the following observation: cells of E. coli fermenting glucose (anaerobic conditions) grow faster when NO3 is supplied to the culture, and then grow even faster when the culture is highly aerated.
Enzyme kinetics
In biochemistry, enzymes are proteins that act as biological catalysts. Catalysis is the addition of a catalyst to a chemical reaction to speed up the pace of the reaction. Catalysis can be categorized as either homogeneous or heterogeneous, depending on whether the catalysts are distributed in the same phase as that of the reactants. Enzymes are an essential part of the cell because, without them, many organic processes would slow down and thus will affect the processes that are important for cell survival and sustenance.
Regulation of Enzymes
A substance that acts as a catalyst to regulate the reaction rate in the living organism's metabolic pathways without itself getting altered is an enzyme. Most of the biological reactions and metabolic pathways in the living systems are carried out by enzymes. They are specific for their works and work in particular conditions. It maintains the best possible rate of reaction in the most stable state. The enzymes have distinct properties as they can proceed with the reaction in any direction, their particular binding sites, pH specificity, temperature specificity required in very few amounts.
![Practice question #7 chap. 2 p. 145
A. Explain the following observation: cells of E. coli fermenting glucose (anaerobic
conditions) grow faster when NO; is supplied to the culture, and then grow even faster
when the culture is highly aerated.
B. Shiga toxin (Stx) is a potent A-B toxin that inhibits protein synthesis and has a lethal dose
50 (LD50) of approximately 20 ng/kg of body weight in rabbits (meaning that 1 µg of Stx
would be lethal for half the people exposed to this dose). Nonetheless, cell lines derived
from different mammalian tissues range from highly susceptible (cytotoxic dose 50 [CD50]
of approximately 10 pg/ml) to completely resistant (CD50 > 1 µg/ml). What cellular or
molecular differences do you think account for susceptibility and resistance of these cell
lines?
Note:
LD50 is the dose at which 50% of the test subjects die. In this case, it was determined for
rabbits given intravenous injections of the toxin.
CD50 is the concentration at which 50% of the cells die. Measure mostly used for tissue
culture lab experiment.](/v2/_next/image?url=https%3A%2F%2Fcontent.bartleby.com%2Fqna-images%2Fquestion%2F13a12895-2170-4054-822b-28216fc24f7f%2F83c68756-505d-4f2c-8927-30e01b04ae7f%2Fkpozp7_processed.png&w=3840&q=75)
Trending now
This is a popular solution!
Step by step
Solved in 2 steps
