Microbiology Assignment: Felber, Exam 2 - Enzymes, Metabolism, Growth

This microbiology assignment delves into several core concepts. It begins by explaining electron transport phosphorylation, detailing the process of energy generation via redox reactions. The assignment then contrasts competitive and non-competitive enzyme inhibition, highlighting how inhibitors affect enzyme function. Central metabolism is described, linking processes like glycolysis and the Krebs cycle to oxygen use patterns. The metabolic changes in a given situation are discussed, incorporating relevant vocabulary related to central metabolism and antioxidant activity. Physical and chemical methods for controlling microbial growth, along with the stages of microbial growth in culture, are outlined. The assignment also explores the physical factors inhibiting enzyme activity. Finally, the extra credit question addresses the burial site in Grant's Tomb.

Running head: BIOTECHNOLOGY 1
Biotechnology
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Institution of Affiliation
Date of Submission

BIOTECHNOLOGY 2
1. Describe how electron transport phosphorylation works.
Electron transport phosphorylation refers to the process in which electrons are passed from one
transport chain to another in a series that involves redox reactions. Energy is released from these
redox reactions which is captured as a proton gradient then utilized to make ATP.
The electron transport in bacteria occurs in aerobic conditions where NADH is the electron
donor and the Ubiquinone is the connecting link between NADH dehydrogenase (Plessis et al.,
2015).
2. Compare and contrast the types of enzyme inhibition we went over in class.
Feedback inhibition of an activity refers to inhibition of an enzyme when the substance
accumulates to a certain level. The different types of feedback inhibition include competitive and
non-competitive inhibition. In contrast competitive and non-competitive inhibitors interferes the
functioning of the active site of an enzyme thus lowering the number of enzyme-substrate
complexes that can form.
a. Competitive inhibition occurs when a molecule similar in shape to the substrate
molecules binds to the active site of the enzyme. They therefore compete with the
substrate for the active site. When they bind to the active site in the enzyme, they block
the substrate from binding. A good example is penicillin which blocks binding of
bacterial enzymes to the active site thus preventing synthesis of bacterial cell wall
(Huang et al., 2017).
b. Noncompetitive inhibition- Unlike competitive inhibition, noncompetitive inhibition
occurs when an inhibitor binds to the enzyme at a location referred to as the allosteric site
other than the active site. Upon attachment to the allosteric site, the inhibitor alters the

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shape of the enzyme thereby changing the shape of its active site thus preventing the
substrate from binding. Since the inhibitor and the substrate are not in competition for the
active site, increasing the concentration of substrate does not lower the effect of the
inhibitor unlike in the case of competitive inhibition which it would reduce the effect.
3. Describe central metabolism and how it relates to the oxygen use patterns we studied. Do
not submit answers in outline form. Use complete sentences and descriptions.
The central metabolism involves metabolic process such as glycolysis, Krebs cycle, the electron
transport system and oxidative phosphorylation.
a. Glycolysis – This refers to the process which glucose is broken down into two molecules
of ATP, two molecules of pyruvate, 2 molecules of water and 2 molecules of NADH. The
process takes place in cytoplasm and can take place with or without oxygen.
b. Krebs cycle-Refers to metabolic reaction that produces 1 GTP/ATP, 2 molecules of
carbon dioxide and reduced forms of FADH2 and NADH. It takes place in the matrix of
the mitochondria in the presence of oxygen.
c. Electron transport system- This refers to the process in which electrons are passed from
one transport chain to another in a series that involves redox reactions. Energy is released
from these redox reactions which is captured as a proton gradient then utilized to make
ATP. Oxygen is reduced to form water.
d. Oxidative phosphorylation- This involves the process in which ATP is formed due to the
transfer of electrons from NADH or FADH2 to oxygen by a series of electron carriers.
The process takes place in the mitochondria and is the primary source of ATP in aerobic
organisms.

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4. Describe the metabolic changes that likely occur in the following situation. Include all
relevant vocabulary related to central metabolism and antioxidant activity.
One of the metabolic changes that occur is the metabolic energy which is derived from the
process of oxidation and reduction reactions in the central metabolism. When energy is used in
the process, the chemical energy is made available for the production of ATP as 1 atom which
gives up electrons by becoming oxidized and the other atom accepts the electrons (reduced).
5. Describe physical and chemical methods used to control microbial growth. Do
The various physical and chemical methods utilized to control microbial growth include pH,
temperature, oxygen concentration, moisture, hydrostatic pressure and osmotic pressure.
a. Ph-Temperature- Increasing the temperature increases the increases the enzyme activity
but when it becomes too high it denatures their protein thus stopping their growth.
Lowering the temperature decreases their enzyme activity thus reduced growth (Maggio,
2018).
b. Oxygen concentration- Obligate aerobes depend on aerobic respiration and utilize oxygen
as a terminal electron acceptor. Optimum oxygen concentration facilitates their growth
whereas low or no oxygen inhibits their growth.
c. Moisture- Microbial growth is affected by the amount of moisture. Increase in moisture
content facilitates their growth whereas reducing the moisture content inhibits their
growth.
d. Hydrostatic pressure- High hydrostatic pressure inhibits microbial growth whereas lower
hydrostatic pressure promotes their growth.

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e. Osmotic pressure- Osmotic pressure is a crucial factor in microbial growth. Having the
correct osmotic pressure in a culture is crucial as it affects the microbial growth in
various ways.
6. Outline and describe the stages of microbial growth in culture.
The different stages of microbial growth in a culture include;
a. Lag stage- This is the initial phase which is characterized by cellular activity with no
growth. The bacterial cells in a nutrient rich medium synthesize proteins and other
molecules that are crucial for replication. The cells at this stage increases in size and does
not undergo cell division.
b. Long stage- Also referred to as exponential phase where the cells start dividing by binary
fission and doubling in numbers. In this phase, the metabolic activity is very high as
DNA, RNA and other substances which are important for growth are generated for cell
division (Maier & Pepper, 2015).
c. Stationary stage-In this phase the population growth of the cells starts to decline as the
available nutrients becomes depleted and waste products starts to build up thus resulting
to no overall population growth.
d. Death stage- The last phase of microbial growth where the cells starts to die as nutrients
become less available and the waste products piles up. In this phase, the number of living
cells decreases exponentially and the population growth experiences a sharp decline.

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7. Describe the physical factors that inhibit enzyme activity. Do not submit answers in
outline form. Use complete sentences and descriptions.
The physical factors that inhibit enzyme activity include ph, temperature, concentration of an
enzyme and concentration of substrates.
a. Ph- A pH which is higher or lower than the optimal pH of the enzyme inhibits the
enzyme activity. Most of the enzymes work at neutral pH 7.4.
b. Temperature- The enzymes have proteins that are extremely sensitive to slight thermal
changes and each enzyme has its optimal temperature. A temperature higher or lower
than the optimal temperature of an enzyme inhibits the action of an enzyme.
c. Concentration of an enzyme- An increase in enzyme concentration speeds up the activity
whereas a reduction in enzyme concentration inhibits the activity of the enzyme (Feng et
al., 2015).
d. Concentration of substrates- Substrate refers to molecules in which the enzyme binds. An
increase in substrate concentration increases the activity of enzyme whereas a reduction
in substrate concentration inhibits the activity of the enzyme. .
8. EXTRA CREDIT- Who is buried in Grant's Tomb? Grant’s Tomb is located on the Upper
west side of Manhattan whose design is based on Mausoleum at Halicarnassus. In my
understanding I think there is nobody who is buried at Grant’s Tomb.

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References
Feng, D., Liu, T. F., Su, J., Bosch, M., Wei, Z., Wan, W., ... & Lian, X. (2015). Stable metal-
organic frameworks containing single-molecule traps for enzyme encapsulation. Nature
communications, 6(1), 1-8.
Huang, G., Chen, S., Dai, C., Sun, L., Sun, W., Tang, Y., ... & Ma, H. (2017). Effects of
ultrasound on microbial growth and enzyme activity. Ultrasonics sonochemistry, 37, 144-
149.
Maggio, E. T. (2018). Enzyme Immunoassay: 0. Crc Press.
Maier, R. M., & Pepper, I. L. (2015). Bacterial growth. In Environmental microbiology (pp. 37-
56). Academic Press.
Plessis, S. S., Agarwal, A., Mohanty, G., & Van der Linde, M. (2015). Oxidative
phosphorylation versus glycolysis: what fuel do spermatozoa use?. Asian journal of
andrology, 17(2), 230.