MCB 3020L Chapter Notes - Chapter 18: Antibiotics, Peptidoglycan, Streptomycin

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21 Mar 2017

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Antiseptics and disinfectants are both types of methods to reduce the numbers of bacteria, but generally do not result in total sterilization: both are also forms of chemical bacterial control. Disinfectants: chemicals applied to surfaces of inanimate objects. Antiseptics: chemicals applied to the surfaces of tissues. Diffferent chemicals have different effects on bacteria: some attack the peptidoglycan layers of the cell wall and the cell membrane, leading to the lysis of the cells. Bactericidal: chemical agents that are able to cause total cell death of the bacteria; kills the bacteria like straight up. Bacteriostatic agents: are able to temporarily inhibit the growth of certain bacteria, but are not able to kill the cells. Concentration is very important: too low bacteria may be effected, too high may be toxic to the user, cause damage to the surface treated, or prohibitively expensive.

Related Questions

31. What is the length of time required for a chemical agent (or condition) to kill 90% of a microbial population?

(A) death time (B) partial sterilization time

(C)killing period (D)decimal reduction time

(E) sanitation time

32. The process by which allliving cells, spores, and viruses are destroyed on an object is called

(A) sterilization. (B) disinfection.

(C)antisepsis. (D)sanitation.

(E) all of the above

33. Some endospores can survive an autoclave treatment. Based on the conditions of an autoclave, endospores are _____ and ____ compared to their vegetative cell counterparts.

(A) barophilic / psychrophilic (B) acidophilic / mesophilic

(C)halophilic / barotolerant (D)alkaliphilic / aerotolerant

(E) barotolerant / thermophilic

34. A woman with digestive problems attempts to restore normal gut microflora by ingesting yogurt containing live, active cultures. This is an example of using

(A) antibiotics. (B) probiotics.

(C)phage therapy. (D)bioremediation.

(E) disinfectants.

35. What is the relationship between osmolarity and water activity?

(A) There is a negative correlation; as osmolarity increases water activity also increases.

(B) There is a positive correlation; as osmolarity increases water activity decreases.

(C)There is no correlation between osmolarity and water activity.

(D)There is a negative correlation; as osmolarity increases water activity decreases.

(E) There is a positive correlation; as osmolarity increases water activity also increases.

36. Which of the following enzymes generates hydrogen peroxide when destroying a reactive oxygen species?

(A) superoxide dismutase (B) catalase

(C)peroxidase (D)ATP synthetase

(E) NADH dehydrogenase

37. A genetic program leading to the production of chaperones, proteases, and enzymes that change membrane lipid composition, in response to adverse environmental conditions, is known as the

(A) irradiation response. (B) high pressure response.

(C)halophilic response. (D)Arrhenius response.

(E) heat shock response.

38. Changes in environmental temperature may

(A) affect the fluidity of bacterial membranes.

(B) affect the motion of macromolecules within the bacterial cell.

(C)affect the stability of molecules within bacteria.

(D)all of the above.

(E) none of the above.

39. Within temperatures allowable for growth, higher temperatures usually lead to

(A) higher growth rates. (B) slower growth rates.

(C)no effect on growth rates. (D)unpredictable growth rates.

(E) variable effect, depending on the species.

40. Which of the following sentences is correct?

(A) Sanitation kills all cells, spores, and viruses on an object, sterilization removes pathogens from inanimate surfaces, and disinfection removes pathogens from the surface of living tissues.

(B) Disinfection kills all cells, spores, and viruses on an object, antisepsis removes pathogens from inanimate surfaces, and sterilization removes pathogens from the surface of living tissues.

(C)Sterilization kills all cells, spores, and viruses on an object, disinfection removes pathogens from inanimate surfaces, and antisepsis removes pathogens from the surface of living tissues.

(D)Disinfection kills all cells, spores, and viruses on an object, sterilization removes pathogens from inanimate surfaces, and antisepsis removes pathogens from the surface of living tissues.

(E) Sanitation kills all cells, spores, and viruses on an object, sterilization removes pathogens from inanimate surfaces, and antisepsis removes pathogens from the surface of living tissues.

Microbiology Unit 2 Applied and Environmental Assignment Part 1: Identify Nutritional requirements from Chapter 6&14 (and review from chapters 1 & 2) 1. Determine which of the 4 macromolecules require the following elements: a. Carbon: carbohydrates___ lipids___ proteins___ nucleic acids___ b. Nitrogen: carbohydrates___ lipids___ proteins___ nucleic acids___ c. Sulfur: carbohydrates___ lipids___ proteins___ nucleic acids___ 2. The essential elements mentioned above are cycled through cells and the earth in biogeochemical cycles (the carbon, nitrogen, and sulfur cycles.)Select the correct answer or fill in the blanks to summarize these cycles: a. Carbon dioxide is taken in from the atmosphere by [autotrophs/heterotrophs] and converted to glucose through carbon ________________. When heterotrophs eat autotrophs they use catabolism to break down glucose to make ATP and waste carbon is released as ___________. b. There is plenty of nitrogen available in the atmosphere but it is not accessible to organisms because it is in the form of Nitrogen gas (N2). N2 is fixed by [bacteria/plants/animals] and converted to ammonia (NH3.) NH3 can be used by [bacteria/plants/animals] to build their cells. Next, by consuming food with amino acids,[bacteria/plants/animals] can get access to nitrogen for their own cellular needs. c. There is also a good quantity of sulfur in dirt, rocks, and the atmosphere. Sulfur cycles between H2S => S0 => SO4 => SH groups in Proteins => back to H2S.Using _________________ respiration, anoxygenic photosynthesis, and chemolithoautotrophy [bacteria/plants/animals]convert H2S and S0 to SO4 which is taken in by [bacteria/plants/animals] and used to build their cells. When [bacteria/plants/animals]eat plants they take in essential amino acids containing sulfur and recycle these to make their proteins. d. _________________ break down waste and dead organisms and recycle nutrients back into the cycles. *The C and N are summarized here: https://youtu.be/2D7hZpIYlCA and https://youtu.be/leHy-Y_8nRs 3. Match the main metabolic classifications to the description: Classifications: photoautotroph/ photoheterotroph/ chemoautotroph/ chemoheterotroph o A microbe that makes its own food by taking carbon from CO2 in the atmosphere and its energy from sunlight o A microbe that makes its own food by taking carbon from CO2 in the atmosphere and its energy from reduced inorganic chemicals o A microbe that eats other organisms to get organic carbon and energy o A microbe that eats other organisms to get organic carbon but gets energy from sunlight 4. Identify the phases of the bacterial growth curve and define what occurs in each phase Phase A = ______________ Definition: Phase B = ______________ Definition: Phase C = ______________ Definition: Phase D = ______________ Definition: Part 2: Unique ecosystems containing microbes 5. Watch the video that shows hydrothermal vents: https://youtu.be/RO3nO98gH_M a. Describe bacteria that live at the vents using terms from the unit 2 reading guide: ________________________________________________________________________ b. Write a 2-3 sentence reflection about hydrothermal vents and the contribution of microbes to this ecosystem: 6. Apply what you have learned to the TED-Ed video about Biofilms: https://youtu.be/pHLP5CZMnL4 a. Give the terms for cell structures mentioned in the video that we learned in Chapter 4 and 7: i. âsticky appendagesâ thatallows bacteria to attach and begin the biofilm: _______________ ii. Extracellular matrix/gooey matrix that holds cells together: ____________________________ iii. Exchange genetic information while packed together: ____________________________ iv. Communicate with each other by _________________________________________ sensing. v. Produce chemical to kill microbial competitors: ____________________________ factor.

Class 6: Viruses (and Cells, continued)

Making connections: viruses and microbes Match the cell biology concept (on page 1) with an important application of that concept (on page 2). Then answer the follow-up questions at the bottom of page 2.

Cell Biology concepts
1. Bacteria that cannot construct new cell wall material become fragile and break down.
2. During influenza infection, the viral enzyme neuraminidase is required to release new viruses from the host cell in which they were made. Once released, the new viruses can infect many additional cells.
3. Thermus aquaticus is a bacterium found in hot springs and can live at temperatures up to ~80Â°C (175Â°F). It has adapted so that its enzymes are most functional at the elevated temperatures, compared with many organismsâ enzymes that function best ~37Â°C (98Â°F).
4. Until the isolation and investigation of retroviruses, scientists thought that RNA could be copied from DNA, but DNA could not be copied from RNA. Research on this class of viruses led to an update to this âCentral Dogmaâ of biology.
5. Some bacteria have adapted, so that the enzymes involved in making cell wall materials have a slightly different shape and can no longer be bound by certain drugs.
6. Rhizobia are bacteria that colonize the roots of certain plants (legumes, including beans and peas). The host plant benefits from the prokaryotesâ ability to âfixâ nitrogen, converting N2 from the atmosphere into a form that is usable by the plant.
7. Many species of bacteria contain the enzyme cellulase. More than 10 billion such bacteria and other symbiotic microbes may be found in a single milliliter of material from inside the digestive system of ruminant mammals.
8. Fungi, including those that cause athleteâs foot, use ergosterol to maintain healthy membranes. Animal cells do not make ergosterol, they use a similar lipid â cholesterol.
9. During retrovirus infection, a DNA copy is made of the virusâs RNA genome. A cut is made in the host cellâs DNA and the DNA copy of the viral genome is pasted into the host chromosome by a viral enzyme called integrase.
10. Prokaryotic cells contain smaller ribosomes (â70Sâ ribosomes) than eukaryotic cells (â80Sâ ribosomes). Both types of ribosomes synthesize proteins, but the macromolecules they use to do it are somewhat different.

2
Applications
_______ Oseltamivir, also called Tamiflu, binds and inhibits the viral protein neuraminidase.
_______ Clotrimazole is a drug that is used to treat certain infections. It interferes with synthesis of ergosterol, a lipid involved in phospholipid membranes.
_______ Penicillin is a drug that interferes with synthesis of peptidoglycans (these are biological molecules that are part protein and part carbohydrate) that are present in certain cell walls.
_______ HIV is often treated with several drugs that inhibit different parts of the viral replicative cycle. Raltegravir is an example of a drug that interferes with the integration of viral genes into the host cellâs chromosome.
_______ Cows, like other vertebrates, lack the ability to breakdown cellulose. Yet they are able to live on a diet of grass and other vegetation high in cellulose.
_______ Enzymes isolated from extremophiles have been very useful in laboratory research. For example, Taq polymerase facilitates PCR, a revolutionary technique for production of DNAs of particular sequences, which requires cycling reactions through high temperatures.
_______ Plants and animals require nitrogen to make biological macromolecules, however theyâre unable to convert atmospheric nitrogen (N2) into a biologically useful form.
_______ Azithromycin is a drug that binds to 70S ribosomes and blocks synthesis of any new proteins.
_______ Methicillin-Resistant Staphylococcus aureus (MRSA) can cause life-threatening infections of the skin and bloodstream. One of the reasons MRSA infections are so serious is that they are resistant to treatment by many antibiotics, including methicillin and penicillin.
_______ The enzyme reverse transcriptase, isolated from retroviruses, is an important tool in molecular biology research. Scientists interested in learning what genes are turned on in particular cells use it to make DNA copies of RNAs they are studying (The DNA copies are useful because they are more stable).

When you have completed the matching activity, answer these follow-up questions:
â¢ What types of infections can be treated with the following drugs?
o Penicillin
o Clotrimazole
o Azithromycin
o Tamiflu
o Raltegravir
â¢ Why are these drugs (above) safe for you to take? That is, why donât they kill your cells?
â¢ Cancer cells are your own human cells that have become deregulated so that they divide and pile up in an uncontrolled way. Many chemotherapy drugs treat cancer by interfering with cell division and other cell processes.
o Why are there so many more side effects for individuals undergoing chemotherapy than for individuals taking antibiotics?

MCB 3020L Chapter Notes - Chapter 18: Antibiotics, Peptidoglycan, Streptomycin

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