Unit 6 Discussion (Zoom)

Question 1

A lichen is an intimate relationship between fungi and a photosynthetic microbe in which the fungi deliver water and minerals to the photosynthetic partner, which delivers sugar to the fungi. What type of symbiosis is involved?

Answer 1

Mutualism;

Both benefit from this relationship

Question 2

What type of symbiosis do the following have?
a. Barnacles growing on whales
b. Tapeworms and humans

Answer 2

a. Barnacles growing on whales

Commensalism; barnacles use whale for food/transport while whale is not harmed or benefits from this relationship

b. Tapeworms and humans

Parasitism; tapeworms get food, humans lose nutrients

Question 3

What physical agent targets Oxidization?

Answer 3

Dry heat

Question 4

What 7 physical agents Denature/inactivate proteins (enzymes)–inhibit metabolism?

Answer 4

1. Autoclave
2. Pasteurization
3. UHT sterilization
4. Dry heat
5. Refrigeration/freezing
6. Desiccation
7. Osmotic pressure

Question 5

What 4 physical agents Destroy the CM?

Answer 5

1. Autoclave
2. Pasteurization
3. UHT sterilization
4. Dry heat

Question 6

What physical agent Damages Nucleic Acids?

Answer 6

Radiation

Question 7

What physical agent targets a Barrier?

Answer 7

Filtration

Question 8

What 8 chemical agents Denatures/inactivates proteins (enzymes)?

Answer 8

1. Phenolics
2. Alcohol
3. Halogens
4. Oxidizing agents
5. Heavy metals
6. Aldehydes
7. Gases
8. Enzymes

Question 9

What 3 chemical agents Destroy CM?

Answer 9

1. Phenolics
2. Alcohol
3. Surfactants/quats

Question 10

What 2 chemical agents Damage Nucleic acids?

Answer 10

1. Aldehydes
2. Gases

Question 11

A virologist needs to remove all bacteria from a solution containing viruses without removing the viruses. What size membrane filter should the scientist use?

Answer 11

Between 0.22 to 0.45 micrometers;

Because viruses are very small

Question 12

During the fall 2001 bioterrorist attack in which anthrax endospores were sent through the mail, one news commentator suggested that people should iron all their incoming mail with a regular household iron as a means of destroying endospores. Would you agree that this is a good way to disinfect mail? Explain your answer. Which disinfectant methods would be both more effective and more practical?

Answer 12

• Anthrax spores are highly resistant to extreme conditions, including heat, and can withstand temperatures far above what a typical household iron can achieve

For anthrax spores, effective and practical disinfectant methods are challenging to find for home use, as spores are highly resistant to typical household methods. However, some approaches are both more effective and practical:

1. UV-C Light: High-intensity UV-C light can help inactivate spores on surfaces, although it requires direct exposure and time to be effective.
2. Chlorine Dioxide: Chlorine dioxide gas or solutions are effective against spores, though gas application requires special equipment and is primarily used by professionals. However, chlorine dioxide wipes or solutions are available for home disinfection, although they must be handled carefully due to potential toxicity.
3. Bleach Solution: A solution of household bleach (sodium hypochlorite) at a high concentration (about 10% bleach in water) can inactivate anthrax spores, though it requires sufficient contact time (at least 30 minutes). While practical, it can damage paper and other materials.

Question 13

Some potentially pathogenic bacteria and fungi, including strains of Enterococcus, Staphylococcus, Candida, and Aspergillus, can survive for one to three months on a variety of materials found in hospitals, including scrub suits, lab coats, and plastic aprons and computer keyboards. What can hospital personnel do to reduce the spread of these pathogens?

Answer 13

1. Regular Hand Hygiene: Wash hands thoroughly and frequently with soap and water or use alcohol-based hand sanitizers, before and after patient contact.
2. Frequent Disinfection of High-Touch Surfaces: Regularly disinfect surfaces such as keyboards, doorknobs, light switches, and medical equipment with appropriate hospital-grade disinfectants.
3. Routine Cleaning of Uniforms: Personnel should change and clean lab coats, scrubs, and plastic aprons frequently, ideally after each shift. These items should be laundered at high temperatures to effectively kill pathogens.
4. Use of Disposable or Single-Use Items: Where possible, use disposable equipment and coverings (e.g., plastic aprons, paper keyboard covers) to minimize pathogen transfer.
5. Proper Personal Protective Equipment (PPE): Wear gloves, masks, and gowns as required, especially when in contact with vulnerable patients or contaminated surfaces, and dispose of PPE properly after use.
6. Ultraviolet (UV) Disinfection: Consider using UV-C light devices to disinfect rooms and equipment regularly, especially in high-risk areas like operating rooms and ICUs.
7. Strict Infection Control Protocols: Follow strict protocols for cleaning and disinfecting rooms, especially after each patient, and for handling contaminated materials.
8. Education and Training: Regularly train staff on infection control measures, proper disinfection techniques, and hygiene practices to maintain high standards.

Question 14

Over 1000 people developed severe diarrhea, and at least four died, from a strain of Salmonella enterica in the fall of 2012. Epidemiologists determined that infection resulted from the consumption of contaminated smoked salmon. Based on this chapter, what methods to control microbial growth are available to fishermen, packers, and retail stores that might have prevented such an outbreak? What other precautions could consumers have taken?

Answer 14

1. Proper Refrigeration and Temperature Control:
   
   • Keep fish stored at cold temperatures (below 4°C or 39°F) throughout the supply chain to slow bacterial growth.
   • Use blast freezing or rapid freezing methods to quickly lower temperatures and reduce microbial contamination.
2. Salting and Brining:
   
   • Salting or brining fish before smoking helps reduce bacterial levels. The salt concentration creates an environment hostile to many pathogens, including Salmonella.
3. Smoking and Heating Processes:
   
   • Use hot-smoking processes (temperatures above 63°C or 145°F) to kill pathogens. Cold-smoking alone does not eliminate bacteria, so combining smoking with pasteurization (or using hot-smoking) is more effective.
4. Proper Handling and Sanitation:
   
   • Ensure all equipment, surfaces, and storage containers are sanitized regularly to avoid cross-contamination.
   • Educate workers on hygiene practices, including handwashing and proper handling.

Question 15

Over 1000 people developed severe diarrhea, and at least four died, from a strain of Salmonella enterica in the fall of 2012. Epidemiologists determined that infection resulted from the consumption of contaminated smoked salmon. Based on this chapter, what methods to control microbial growth are available to fishermen, packers, and retail stores that might have prevented such an outbreak? What other precautions could consumers have taken?

Answer 15

1. Purchase from Reputable Sources: Buy smoked salmon from trusted suppliers that adhere to food safety practices.
2. Check Storage Conditions: Ensure smoked salmon is properly refrigerated and stored at home to prevent bacterial growth.
3. Reheat Smoked Fish: If possible, heating smoked salmon to 74°C (165°F) before consumption can kill potential pathogens, though this may change the texture.
4. Practice Safe Food Handling: Wash hands, utensils, and surfaces after handling raw fish to prevent cross-contamination.

Question 16

Tsunamis and hurricanes severely contaminate water wells and disrupt water supply lines. What immediate steps should people take to lessen the spread of waterborne illnesses such as cholera?

Answer 16

1. Boil Water: Boil all drinking water for at least 1-3 minutes to kill bacteria, viruses, and parasites.
2. Practice Good Hygiene: Regularly wash hands with soap and safe water, especially before eating or preparing food and after using the bathroom, to prevent disease transmission.
3. Disinfect Surfaces and Cooking Utensils: Clean surfaces, dishes, and utensils with safe, disinfected water and bleach solution if they may have been exposed to contaminated water.

1. Filtration: Portable water filters with pore sizes of 0.1 to 0.4 microns can remove many bacteria and protozoa.
2. Ultraviolet (UV) Light: UV light devices are effective at inactivating bacteria and viruses in small quantities of water.

Chemical Agents
1. Chlorine-Based Disinfectants: Chlorine tablets, liquid bleach (sodium hypochlorite), and chlorine dioxide are widely used to disinfect water. Adding 8 drops of household bleach per gallon of water and allowing it to sit for 30 minutes can make it safe for drinking.

2. Iodine Tablets: Iodine is another chemical agent effective in killing bacteria and viruses in water. Prolonged use is not recommended, especially for people with thyroid conditions, pregnant women, or children.
3. Ozone Treatment: Ozone is a powerful oxidizing agent that kills bacteria, viruses, and other pathogens in water.
4. Hydrogen Peroxide: In combination with other agents like UV light, hydrogen peroxide can help disinfect water and surfaces. It is generally used for surface disinfection rather than for direct water purification.

Question 17

Is desiccation the only antimicrobial effect operating when grapes are dried in the sun to make raisins? Explain.

Answer 17

No,

While desiccation (drying) removes water and inhibits microbial growth by creating an environment where bacteria, molds, and yeasts cannot thrive, other antimicrobial effects also play a role:

1. UV Radiation from Sunlight: Exposure to sunlight introduces UV radiation, which can damage microbial DNA, thereby reducing microbial load on the surface of the grapes. This effect adds to the antimicrobial action during sun drying.
2. Increased Sugar Concentration: As water is removed, the natural sugars in the grapes become more concentrated, creating a hypertonic environment. This high sugar concentration draws water out of microbial cells through osmosis, which can inhibit or kill many types of microbes.
3. Temperature: Sun drying often raises the surface temperature of the grapes, which can further inhibit microbial growth. While temperatures during drying may not be high enough to kill all microbes, they can contribute to reducing microbial activity.

Question 18

What 2 antimicrobial drugs Inhibit CW synthesis?

Answer 18

1. Antibacterial
2. Antifungal

Question 19

What 3 antimicrobial drugs Inhibit protein synthesis?

Answer 19

1. Antibacterial
2. Antiviral
3. Anti-protozoan

Question 20

What 2 antimicrobial drugs Disrupt lipids?

Answer 20

1. Antibacterial (CM)
2. Antiviral (Envelope)

Question 21

What 4 antimicrobial drugs Inhibit metabolic pathway?

Answer 21

1. Antibacterial
2. Antifungal
3. Anti-protozoan
4. Anti-worm

Question 22

What 5 antimicrobial drugs Inhibit nucleic acid synthesis? (all)

Answer 22

1. Antibacterial
2. Antiviral
3. Antifungal
4. Anti-protozoan
5. Anti-worm

Question 23

What antimicrobial drug affects Entry & uncoating?

Answer 23

Antiviral

Question 24

How does Penicillium escape the effects of the penicillin it secretes?

Answer 24

1. Lack of Target: Penicillium, as a fungus, has different cellular structures from bacteria. Penicillin targets bacterial cell wall synthesis, specifically the peptidoglycan layer.

Since Penicillium and other fungi do not have peptidoglycan in their cell walls, they are naturally resistant to the antibiotic they produce.

Question 25

Would you expect Gram-negative bacteria or Gram-positive bacteria to be more susceptible to antimicrobial chemicals that act against cell walls? Explain your answer, which you should base solely upon the nature of the cell’s walls (see Figure 3.15).

Answer 25

Gram-positive bacteria have a thicker peptidoglycan layer in their cell wall, which is the target of many antimicrobial agents like penicillin.

The thick peptidoglycan layer is exposed on the outside of the cell and is more easily disrupted by these chemicals.

Gram-negative bacteria, have a much thinner peptidoglycan layer and an additional outer membrane that acts as a protective barrier.

This outer membrane prevents many antimicrobial chemicals from reaching the peptidoglycan layer

Question 26

Why aren’t antibiotics effective against the common cold?

Answer 26

Antibiotics are not effective against the common cold because the common cold is caused by viruses, not bacteria. Antibiotics are designed to target bacterial infections, either by killing bacteria or inhibiting their growth, but they have no effect on viruses.

Question 27

AIDS is treated with a “cocktail” of several antiviral agents at once. Why is the cocktail more effective than a single agent? What is a physician trying to prevent by prescribing several drugs at once?

Answer 27

A “cocktail” of several antiviral agents is more effective than a single drug because it targets the HIV virus at multiple stages of its life cycle.

By using multiple drugs, physicians prevent the virus from mutating and becoming antibiotic resistant

Question 28

Antiparasitic drugs in the benzimidazole family inhibit the polymerization of tubulin. What effect might these drugs have on mitosis and flagella?

Answer 28

Mitosis: Antiparasitic drugs in the benzimidazole family would disrupt mitosis by preventing the proper formation of microtubules, which are essential for chromosome separation during cell division.

Flagella: These drugs would also impair flagella movement by inhibiting the polymerization of tubulin, disrupting the structure and function of the flagella.

Question 29

Your cousin reads in a blog that the U.S. Food and Drug Administration (FDA) has approved an antimicrobial called tigecycline. The blog says that the drug is an analog of tetracycline. She asks you what that means and how the drug works. What should you tell your cousin?

Answer 29

Tigecycline is an antimicrobial drug that is chemically similar to tetracycline, meaning it is a tetracycline analog, designed to work in a similar way but with modifications that allow it to be effective against a broader range of bacteria.

It works by binding to the bacterial ribosome, inhibiting protein synthesis and preventing bacteria from growing and reproducing.

Tigecycline is particularly useful for treating infections caused by drug-resistant bacteria, as its modifications allow it to overcome some bacterial resistance mechanisms that affect tetracycline.

Question 30

Will P. died of E. coli infection after an intestinal puncture. Explain why this microbe, which normally lives in the colon, could kill this patient.

Answer 30

E. coli, while normally harmless in the colon, can become deadly when it enters other parts of the body, such as the bloodstream, due to an intestinal puncture.

Once outside the colon, E. coli can cause severe infections, including sepsis and organ failure, by releasing toxins like Shiga toxin, which can lead to widespread tissue damage.

Question 31

Enterococcus faecium is frequently resistant to vancomycin. Why might this be of concern in a hospital setting in terms of developing resistant strains of other genera of bacteria

Answer 31

The resistance of Enterococcus faecium to vancomycin is concerning in a hospital setting because it can act as a reservoir of resistance genes, potentially transferring these genes to other, more harmful bacteria.

This gene transfer could result in the development of multidrug-resistant strains in other genera, making infections harder to treat and increasing the risk of widespread resistance in hospital-acquired infections.

Question 32

Your pregnant neighbor has a sore throat and tells you that she is taking some tetracycline she had left over from a previous infection. Give two reasons why her decision is a poor one.

Answer 32

Tetracycline binds to calcium which the baby needs for development of bones and teeth

Could cause antibiotic resistance

Question 33

Explain why there may be a difference or similarity in target sites. In other words, why would it be more difficult to find an antiviral drug, an anti-fungal drug and/or even a drug against a protozoan than an antibacterial drug?

Answer 33

• Viruses lack many of their own structures and machinery, relying on host cells for replication, making it hard to target the virus without also damaging the host cells.
• Fungi and protozoa are eukaryotic organisms like humans, so targeting unique structures or processes without harming human cells is challenging.

In contrast, bacteria are prokaryotic and have unique features, such as cell walls and specific ribosomal structures, which allow for more selective targeting with antibiotics.

Question 34

Remember how SARS-CoV2 replicates. If you worked for a biotech company developing an antiviral to slow or stop Covid-10 infections, then what target site(s) would you make your drugs to attack with little or no side effects to the patient?

Answer 34

1. Viral enzymes:
   
   • Protease: prevent virus from processing its polyproteins (viral replication)
   • RNA-dependent RNA polymerase (RdRp): Inhibiting would block replication of viral RNA genome (no copies)
2. Spike protein or receptor-binding domain (RBD): spike protein ineraction with ACE2 receptor (prevent virus from entering & infecting host cells)

These targets are specific to the virus and not found in human cells, so drugs aimed at these sites would likely have minimal side effects for the patient.

Question 35

What DNA does bacteria pick up?

Answer 35

Naked DNA

Question 36

pGLO plasmid:

What is the gene for antibiotic resistance?

Answer 36

bla

Question 37

pGLO plasmid:

What is the glow in the dark jelly fish gene?

Answer 37

GFPgene

Question 38

pGLO plasmid:

What is used to control the expression of the GFP gene?

Answer 38

Arabinose operon (araC)

Question 39

What two things can the pGLO experiment test for?

Answer 39

(Antibiotic resistance and transformation)

Questions:
Was the transformation successful?
Is there gene expression of the GFP gene?

Question 40

What does growth tell you on the pGLO experiment

LB + Amp + pGlo

Answer 40

The bacteria is not antibiotic resistant;

If there is no growth than it is

Question 41

What tells you that gene expression of GFP occurred?

Answer 41

LB + Amp + Ara + pGlo plate growth that grows

Question 42

Place these organisms in order from the most resistant to most susceptible:

1. Enveloped virus
2. Protozoan cysts
3. Most gram negative bacteria
4. Most gram positive bacteria
5. Prions
6. Fungi
7. Mycobacterium
8. Protozoan (trophozoites)
9. Bacterial endospores
10. Naked virus

Answer 42

Most resistant

1. Prions
2. Bacterial endospores
3. Mycobacteria
4. Protozoan cysts
5. Naked virus
6. Protozoan (trophozoites)
7. Most gram negative bacteria
8. Fungi
9. Most gram positive bacteria
10. Enveloped virus

Most susceptible

Question 43

Name the 4 types of symbioses

Answer 43

1. Commensalism +/0
2. Parasitism +/-
3. Mutualism +/+
4. Amensalism 0/-

Question 44

Describe the 4 types of symbioses

Answer 44

1. Commensalism +/0
   one benefits; other nothing happens
2. Parasitism +/-
   one benefits, other is harmed
3. Mutualism +/+
   both benefit
4. Amensalism 0/-
   one nothing happens, other is harmed

Question 45

Identify the type of symbiosis in the given example:

E. coli in our intestine makes vitamin K

Answer 45

Mutualism +/+
both benefit

Question 46

Identify the type of symbiosis in the given example:

S. epidermidis found on your skin

Answer 46

Commensalism +/0
one benefits; other nothing happens

Question 47

Identify the type of symbiosis in the given example:

Nitrogen-fixing bacteria in the root nodule of pea plants

Answer 47

Mutualism +/+
both benefit

Question 48

Identify the type of symbiosis in the given example:

B. anthracis endospores inhaled by humans

Answer 48

Parasitism +/-
one benefits, other is harmed

Question 49

Identify the type of symbiosis in the given example:

Nemo (clownfish) living in a sea anemone

Answer 49

Commensalism +/0
one benefits; other nothing happens

Question 50

Identify the type of symbiosis in the given example:

Penicillium (makes penicillin) and soil bacteria

Answer 50

Amensalism 0/-
one nothing happens, other is harmed

Question 51

Identify the type of symbiosis in the given example:

Human drinking Giardia in river water

Answer 51

Parasitism +/-
one benefits, other is harmed

Question 52

Determine level of control:

Industrial detergent & hot water used in the restaurant’s dishwasher to clean plates and utensils

Answer 52

Sanitization

Question 53

Determine level of control:

A phlebotomist uses an alcohol swab on the patient’s arm prior to drawing blood

Answer 53

Antisepsis, degerming

Question 54

Determine level of control:

A hiker filters river water through a filter (pore size = 1mm)

Answer 54

Disinfection

Question 55

Determine level of control:

Rinsing your mouth with Listerine mouthwash

Answer 55

Antisepsis

Question 56

Determine level of control:

Storing your toothbrush in a UV-case

Answer 56

Disinfection or sterilization depending upon the wavelength and distance

Question 57

Antisepsis vs. Degerming

Answer 57

Antisepsis: disinfecting flesh with some type of alcohol

Degerming: disinfecting or cleaning skin

Question 58

Examples of disinfectants

Answer 58

1. 10% chlorine bleach
2. Ethylene oxide gas

Question 59

You’re preparing to insert a catheter (from a sterile pouch) in a patient. What is a method of control used?

Answer 59

Iodine

Question 60

Why is it important to know the difference between eukaryotes and prokaryotes?

Answer 60

• They have different structures to target
• So we can target things that make us sick without harming us
• So we can invent antibiotics that target certain things in prokaryotes but doesn’t harm eukaryotes like humans

Question 61

List the 5 potential modes of action of an antibiotic

Answer 61

Inhibition of
1 .Cell wall synthesis
2. Protein synthesis
3. Nucleic acid synthesis
4. Metabolic pathways

5. Interference with cell membrane integrity