Free Essay on Decline/Death Phase- Exponential Decrease in the Number of Bacteria Living Cells.

One reason is because of depleted nutrients that result in growth-limiting. The second reason is an inhibitory factor- organic acid is formed. The two reasons lead to the rate of growth and death being equal.

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• I) Line A. Facultative anaerobes thrive best in environments with sufficient oxygen provision.
• II) Line C. Facultative anaerobes will die if they are deprived of oxygen. They need oxygen to survive.
• III) Line B.

Listeria monocytogenes. The bacteria is a psychrotroph. When raw milk is refrigerated, the growth of this bacterium is facilitated. Bacillus cereus is a mesophile and cannot grow below the temperature in the room.

Section II

• a) When the lac operon is turned off, a repressor protein is responsible for binding the control region upstream and thus prevents the process of transcription. If lactose is present, it induces the operon. Then the transcription and translation processes take place.
• b) The control type is determined by the type of response when there is no regulation proteins. In the cases of positive control, the presence of an activator gene or active regulator-protein expresses the genes. C.R.P. interacts with Sxy to activate transcription in Escherichia coli. C.A.P., also known as catabolite activator protein, binds in the presence of glucose, and if cAMP is altered, then both classes’ concentration is affected.
• c) It is observed in microorganisms culture where phenotypic adaptations are made to the second substrate. Hence microorganisms can feed on various nutrients. It is usually caused by the presence of two sugars during culture growth media. The organism has two growth peaks.

When lactose and glucose are present, the genes of lactose metabolism get low levels of transcription.

They are used sequentially, such that R.N.A. polymerase transcribes efficiently when glucose is exhausted. At the transcription level, there is initiation, elongation, termination, and processing.

Section III

a) Milk is exposed to temperatures 63oC for 30 minutes. HTST kills pathogens while at the same time lowering the bacterial count. The process is also suitable for ultra high temperatures (UHT).

The kinds of treatment help in understanding the equivalent treatment. When it is observed that temperature increases, time needed to kill pathogens is less. Pasteurization is used in the killing of heat-sensitive pathogens in other foods as well. Bacteria count increases if they come out of their pores and thus make the food spoil.

Pasteurization technique is efficient in killing microbes that are heat sensitive. Not the same count of vegetative cells are present during the process.

a) i) It is a wide spectrum antibacterial agent quaternary ammonium. It is charged positively. Lysol could be used as a disinfectant. Sanitize non-living surfaces. Should not be sprayed on the skin.

ii) Triclosan is an antifungal as well as an antibacterial agent that is found in some products used by consumers. The action mechanism is that it inhibits the electron chain of transport. It inhibits respiration and induces leakages.

iii) Hexachlorophene is also called Tabac. Was once being used as a disinfectant. It is considered a safe compound if used for external purposes.

b) Olygodynamic action refers to the ability of limited amounts of heavy metals exerting a lethal effect on cells of a bacterium. Metal compounds mix in small amounts of water and kill microorganisms in a specific way. Thimerosal is a mercury-containing compound. There was no evidence that thimerosal in vaccines was dangerous. The decision to remove it was made as a precautionary measure to decrease overall exposure to mercury among young infants.

c) Bleach contains compound NaClO, and halogen element chlorine Cl. M.O.A. causes cellular biosynthetic alterations of metabolism-phospholipids are affected.

Hypochlorous acid disinfects the same way as chlorine

Chloramine is used in the treatment of waste in water treatments as a secondary disinfectant. Odor and taste of water are improved.

h) The behavior mode of ethanol is disinhibitory effects that are responsible for euphoria and intoxication caused by alcohol. There is the activation of neurotransmitters.

Isopropanol has no known mechanism of action. It has antibacterial properties.

i) The concentration of H+ and hydroxyl O.H. ions determine the efficacy of alkaline and acidic agents. Peracetic acid oxidizes the proteins as well as denaturing them, leading to the disorganization of the outer covering. Swelling takes place when there is a high concentration of H+ ions. Hydrogen peroxide degrades the bacteria. Oxidized molecules are sensitive to proteolysis compared to other molecules. Ozone acts on bacteria using an oxidation process. It attacks the protein capsid to let go, before inactivating.

Disinfectants are agents designed to destroy as well as inactivate microbes. Hydrogen peroxide is a good disinfectant than antiseptic. It destroys the important components of the germs.

j) E.T.O. is a flammable, colorless, and has a faintly sweet odor. Industrial production is by use of silver as a catalyst to oxidize ethylene.

M.O.A.- alkalization reactions with organic compounds and other proteins.

They are used as an intermediate in the production of other industrial chemicals.

Advantage- compatible with various materials as well as minimize the potential of gas leakage.

Disadvantage- comparatively slow action on microorganisms

k) Fermentation

l) When water is absent, desiccation occurs. This condition is where microorganisms cannot reproduce or grow but can retain their viability for a long time. They can resume their growth after water is made available to them. High concentration causes hypotonic solution, and thus the water is microbial.

Section IV

1. They depend on the host for a number of their nutrients. Prokaryotes are unique in their requirement for plasmas. The cholesterol is acquired from the environment.

2. Volutin contains phosphate that has polymerized and is a representation of the storage of inorganic phosphate as well as energy. Poly-β-hydroxybutyric acid and the related compounds are esters of polymeric contained after bacteria acquire lipid droplets.

3. Phospholipids entail a glycerol molecule, a phosphate group and two fatty acids all modified by alcohol. The chains of the fatty acids are nonpolar and uncharged, thus making them hydrophobic. Because of this, they face the inside and away from water molecules, and they meet in the innermost part of the cell membrane.

4. A peptide bond is formed between the carboxyl group of amino acid and the amino group of the amino acids that have been attached to the P-site tRNA. Each peptide bond-formation is categorized by peptidyl transferase- an enzyme with the basis of R.N.A. integrated as part of the 50S subunit of ribosomes.

5. Elements in an atomic ratio of 1 carbon- 2 hydrogens- 1 oxygen. The compounds are called carbohydrates. Carbohydrates are energy giving through glucose. Carbon atoms formulate very complex molecules of inorganic food.as the carbon is released as waste by the human body, the cells convert it into tiny, ATP molecules full of energy. Carbon in glucose is associated with hydrogen atoms, whereas in carbon dioxide, there are no hydrogen atoms.

6. Glycerol is acquired after the process of triacylglycerol hydrolysis is completed. It enters the glycolytic pathway in the form of dihydroxyacetone phosphate. The Krebs cycle is also called the citric acid cycle. The molecules undergo a transformation and can be building blocks of proteins.

7. D.N.A. is composed of sugar deoxyribose, whereas R.N.A. has sugar ribose. The main difference is that ribose has an extra –O.H. group while deoxyribose has –H attachment on the second carbon inside the ring. Also, D.N.A. is double-stranded while R.N.A. is a single-stranded molecule. Yes, since there are special hydrogen bonds that are formed. The bases provide a mechanism that copies genetic information in an existing nucleic acid.

8. The strands make up the double helix and act as complementary to the parental or old D.N.A. strand.

9. A phosphodiester bond.

Works Cited

Murray, Patrick R., Ken S. Rosenthal, and Michael A. Pfaller. Medical microbiology. Elsevier Health Sciences, 2015.