Book Questions CH 9-12 (finished)

Book Questions

CH 9: List the essential nutrients of a bacterial cell.

carbon, hydrogen, oxygen, nitrogen, phosphorus, and sulfur (CHNOPS)

CH 9: Differentiate between macronutrients and micronutrients.

DIffer in the amounts needed by the body and their primary function

Macronutrients, like carbohydrates, proteins, and fats, are needed in larger quantities for energy and building blocks. Micronutrients, primarily vitamins and minerals, are needed in smaller amounts to support various bodily functions and processes. 

CH 9:  List and define four different terms that describe an organism's sources of carbon and energy.

1.Autotroph-(self-feeder) requires only inorganic nutrients and whose sole source of carbon is carbon dioxide.(convert C02 into into organic compounds) 2.Heterotrophs-organism that relies on upon organic compound for its carbon and energy
3.Chemotroph- organism that oxidizes compounds to feed on nutrients.
4.Phototroph(create energy from sunlight)

CH 9: Define saprobe and parasite, and explain why these terms can be an oversimplification.

Saprobes: Obtain substrates from dead plants and animals
Parasites: Live on the bodies of living animals or plants

CH 9: Compare and contrast the processes of diffusion and osmosis.

✅ Similarities:

• Both are passive transport (no energy needed).

• Molecules move from high to low concentration.

  ✅ Differences:

  Diffusion	Osmosis
  Movement of any molecules	Movement of water only
  Can happen without a membrane	Requires a semipermeable membrane
  Example: oxygen spreading in air	Example: water entering plant cells

CH 9: Identify the effects of isotonic, hypotonic, and hypertonic conditions on a cell.

✅ Isotonic solution:

• Same concentration inside and outside the cell.

• No change in cell size—water moves in and out equally.

✅ Hypotonic solution:

• Less solute outside the cell (more water outside).

• Cell swells as water moves in.

• May burst (lyse).

✅ Hypertonic solution:

• More solute outside the cell (less water outside).

• Cell shrinks as water moves out.

CH 9: Name two types of passive transport and three types of active transport.

Two types of passive transport:

1. Diffusion

2. Osmosis

Three types of active transport:

1. Sodium-potassium pump

2. Endocytosis

3. Exocytosis

CH 9: List and define five terms used to express the temperature-related growth capabilities of microbes.

psychrophile, psychrotroph, mesophile, thermophile, and hyperthermophile

CH 9: Summarize three ways in which microorganisms function in the presence of oxygen.

Aerobes: Can use gaseous oxygen in their metabolism and possess the enzymes needed to process toxic oxygen products.
- bacillus & mycobacterium tuberculosis; most fungi

Microaerophiles: harmed by normal atm concentrations of oxygen but require a small amount in metabolism
-Helicobacteri pylori

Anaerobes: Lack the metabolic enzyme systems for using oxygen in respiration.

CH 9:  Identify three other physical factors that microbes must contend with in the environment.

CO2, pH, Osmotic Pressure, Radiation, atm pressure, and other orgs

CH 9: List and describe the five major types of microbial association

• Mutualism

  • Both organisms benefit.

  • Example: Bacteria in your gut help digest food, and they get nutrients.

• Commensalism

  • One benefits, the other is not affected.

  • Example: Skin bacteria live on you without harming or helping you.

• Parasitism

  • One benefits (parasite), the other is harmed (host).

  • Example: Tapeworms absorbing nutrients from the host’s intestine.

• Synergism

  • Two or more organisms cooperate to produce a result they couldn’t achieve alone.

  • Example: Mixed infections where microbes together cause disease.

• Antagonism

  • One microbe inhibits or destroys another.

  • Example: Antibiotic-producing bacteria killing competitors.

CH 9: Discuss characteristics of biofilms that differentiate them from free-living bacteria and their infections.

Biofilms:

• Groups of bacteria stuck together in a sticky layer (matrix).

• Attach to surfaces (like teeth, catheters, rocks).

• More resistant to antibiotics and disinfectants.

• Share nutrients and protect each other.

• Cause chronic, hard-to-treat infections.

Free-living (planktonic) bacteria:

• Live alone or as single cells floating around.

• Easier to kill with antibiotics.

• Usually cause acute infections that are quicker to treat.

CH 9: Summarize the steps of binary fission, and name another method of reproduction used by other bacterial species.

1. Parent cells enlarges
2. Chromosomes are duplicated
3. Cell envelope pulls together in the center of the cell to form a spetum
4. Cell divides into two daughter cells

Another method of reproduction:

• Budding (some bacteria form a new cell as a small outgrowth).

CH 9: Define doubling time, and describe how it leads to exponential growth.

Doubling time:
The time it takes for a bacterial population to double in number.

Exponential growth:
Because each cell divides into two, the population keeps doubling again and again, creating rapid, exponential increase in numbers.

Example:
1 cell → 2 → 4 → 8 → 16...

CH 9:  Compare and contrast the four phases of growth in a bacterial growth curve

1. Lag Phase: newly inoculated cells require a period of adjustment, enlargment, and synthesis
2. Exponential Growth Phase (log phase): The growth curve increases dramtically as long as cells have adequate nutrients and the environment is favorable
3. Stationary Growth Phase: cell enters survival mode and stop growing or grow slowly
4. Death Phase: limiting factors intensify and cells begin to die at an exponential rate

CH 9: Identify one culture-based and one non-culture-based method used for analyzing bacterial growth.

-Culture-based: Length of Generation Time: measure of growth rate; environmental bacteria measured in months.

-Non-culture based - Turbidity: (fast way to count cells through measurement) nutrient solid becomes turbid, or cloudy, as microbes grow; the greater the turbidity, the larger the population -- turbidimeter.

CH 10: 1. Describe the relationship among metabolism, catabolism, and anabolism.

• Metabolism: all chemical reactions and workings of a cell

• Catabolism: breaks the bonds of larger molecules to release energy. conserves energy in the form of ATP

• Anabolism: uses ATP from catabolism for biosynthesis

CH 10: 2. Fully discuss the structure and function of enzymes.

Enzymes are mostly protein. They have unique shapes and function and speed up cellular energy but by speeding up the process they actually save more energy than reactions without enzymes. They also are sensitive to temp and pH.

CH 10: 3. Differentiate between an apoenzyme and a holoenzyme.

• Apoenzyme:

  • The protein part of an enzyme.

  • Inactive on its own.

  • Requires a cofactor to become active.

• Holoenzyme:

  • The complete, active enzyme.

  • Consists of the apoenzyme and its cofactor.

  • Capable of catalyzing a specific chemical reaction.

Helps to remember: In simpler terms, think of it like a key and a lock. The apoenzyme is the key (protein) but without the key's teeth (cofactor), it cannot unlock the door (catalyze a reaction). The holoenzyme is the complete key, ready to open the lock.

CH 10: 4. Differentiate between an endoenzyme and an exoenzyme, and between constitutive and regulated enzymes.

• Exoenzymes: are transported extracellularly and breakdown large food molecules or harmful chemicals. 

• Endoenzymes: are retained intracellularly and function there, they are the majority of the enzymes of metabolic pathways. 

• Constitutive enzymes: are always present in relatively constant amounts, regardless of the cellular environment. 

Regulated enzymes: production is repressed or induced in response to changes in concentration of substrates

CH 10: 5. Diagram the four major patterns of metabolic pathways.

• Linear - products of previous step and required for subsequent step

• Cyclic - starting molecule is regenerated to start process over again

• Branched convergent - initial monomer synthesized into polymer

• Branched divergent - initial polymers catabolized into component polymers

CH 10: 6. Describe how enzymes are controlled.

They are controlled by competitive and noncompetitive inhibition

• Competitive inhibition - competitive inhibitor of similar shape blocks the active site

• Noncompetitive inhibition - rxn blocked because binding of regulatory molecule in regulatory site changes conformation of active site

CH 10: 7. Name the chemical in which energy is stored in cells.

ATP (Adenosine Triphosphate)

CH 10: 8. Create a general diagram of a redox reaction.

-Oxidation: loss of electrons

-Reduction: gain of electrons

-Oxioreductases take electrons from substrates and give them to another

-Always occur in pairs, acceptors and donor

CH 10: 9. Identify electron carriers used by cells.

NADH and FADH

CH 10: 10. Name the three main catabolic pathways and the estimated ATP yield for each.

1. aerobic respiration: 36-38 ATP

2. fermentation: 2 ATP

3. anaerobic respiration: 2-36 ATP

CH 10: 11. Construct a paragraph summarizing glycolysis.

Glucose is enzymatically converted to pyruvic acid, synthesizes 2 ATP and 2 pyruvic acids. 

CH 10: 12. Describe the Krebs cycle and compare the process between bacteria and eukaryotes.

Transfers energy stored in acetyl COA to NAD+ and FAD by reducing them to NADH. (occurs twice). Cytoplasm of bacteria and mitochondrial matrix of eukaryotes

CH 10: 13. Discuss the significance of the electron transport system.

Pays a huge role in cellular respiration and photosynthesis. ATP produces 34 ATPs which is the largest contributor in aerobic

CH 10: 14. State two ways in which anaerobic respiration differs from aerobic respiration.

1. anaerobic does not require oxygen

2. Anaerobic does not produce as much ATP

CH10: 15. Summarize the steps of microbial fermentation, and list three useful products it can create.

Microbial fermentation begins with glycolysis, where glucose is broken down into pyruvate; then, in the absence of oxygen, pyruvate is converted into various end products like alcohol, acids, or gases, while regenerating NAD⁺ to keep glycolysis going.

CH 10: 16. Describe how noncarbohydrate compounds are catabolized.

Biosynthesis and the Crossing Pathways of Metabolism

CH 10: 17. Provide an overview of the anabolic stages of metabolism.

1. Glycolysis: Glucose is broken down into pyruvate, producing a small amount of ATP. 

2. Krebs: Pyruvate is broken down even more and releases carbon dioxide to make more energy carriers.

3. Respiratory chain: Energy carriers are used to make more ATP, and water is formed.

CH 10: 18. Define amphibolism.

Property of a system to integrate catabolic and anabolic pathways to improve cell efficiency.

CH 10: 19. Summarize the overall process of photosynthesis in a single sentence.

​​Photosynthesis is the process by which plants use sunlight, carbon dioxide, and water to produce glucose and oxygen.

CH 10: 20. Discuss the relationship between light-dependent and light-independent reactions.

Light-dependent reactions capture energy from sunlight to produce ATP and NADPH, which are then used by the light-independent reactions (Calvin cycle) to make glucose from carbon dioxide.

CH 10: 21. Explain the role of the Calvin cycle in the process of photosynthesis.

The Calvin cycle uses ATP and NADPH from the light-dependent reactions to convert carbon dioxide into glucose.

CH 11 Distinguish among the terms sterilization, disinfection, antisepsis, and decontamination.

Sterilization - the destruction of all microbial life

Disinfection - destroy most microbial life, reducing contamination on inanimate surfaces

Antisepsis - (aka degermation) same as disinfection except living surface is involved

Decontamination - (aka sanitization) the mechanical removal of most microbes from animate or inanimate surface

CH 11: Identify the types of microorganisms that are most resistant and least resistant to control measures.

Most resistant to least resistant - prions, bacterial endospores, mycobacterium, staphylococcus + pseudomonas, protozoan cyst, protozoan trophozoites, most gram negative bacteria, fungi + fungal spores, nonenveloped viruses, most gram positive bacteria, enveloped viruses

CH 11: Compare the action of microbicidal and microbistatic agents, providing an example of each

General terms for killing or inhibition of microbes are microbicidal and microbistatic. Chemicals used to control microorganisms in the body (antiseptics and drugs) are often chosen for their microbistatic effects because the ones that are microbicidal can be highly toxic to human cells. 

Detergents called surfactant work as microbicidal agents

CH 11: Name four categories of cellular targets for physical and chemical agents.

• the cell wall,

• the cell or cytoplasmic membrane,

• cellular synthetic processes (DNA, RNA),

• proteins.

CH 11 Name six methods of physical control of microorganisms.

Heat, radiation, filtration, ultrasonic waves and cold

CH 11: Compare and contrast moist and dry heat methods of control, and identify multiple examples of each.

• Moist heat works in lower temp and shorter time exposure but has the same effectiveness as dry heat. It changes (denature) protein inside the microbes and make proteins coagulate (turn solid/clump)

Ex: boiling water kills most bacteria, viruses and fungi but not all spores or treating milk which uses lower heat w/o ruining it

• Dry heat dehydrates cells, removing necessary water for metabolic reactions, and it denatures proteins. But, w/o water some proteins stay stable longer, which is why dry heat needs higher temp than moist heat to kill microbes effectively. dry heat completely burn microbes into ash  at a very high temperatures (like in fire or incinerator) 

For ex: flaming loop in the lab or burning medical waste

CH 11: Define thermal death time and thermal death point, and describe their role in proper sterilization.

• TDT- defined as the shortest length of time required to kill test microbes at a specified temperature.

• TDP - defined as the lowest temperature required to kill all microbes in a sample in 10 minutes.

Role in proper sterilization: Both TDT and TDP help determine the right combination of temperature and time needed to ensure products are free of harmful microbes like spoilage agents or pathogens, while also protecting product quality. For example, commercial canneries heat low-acid foods at 121°C for 30 minutes based on these measurements.

CH 11 Explain three different methods of moist heat control.

Boiling water - boils at 100C for 30 minutes kills most non endospores pathogens, including resistant one like tuberculosis bacteria and staphylococci. Disinfection of water, baby materials, food, utensils, bending and clothing from the sick room. Does not sterilize because some resistant cells and endospores survive and items can also be contaminated when removed. 

Pasteurization - (disinfection of beverages) heat is applied to liquids to kill potential agents of infection and spoilage while keeping flavor and food values. Methods: Flash: 71.6°C for 15 seconds and Batch: 63–66°C for 30 minutes. Used for milk, fruit juices, beer and wine. Does not sterilize; endospores and heat resistant microbes may survive. 

steam under pressure - use devices like autoclaves steam under 15 psi pressure reaches 121C, which is hot enough to sterilize. Used in the health & commercial industry for sterilizing instruments and materials. Steam must circulate freely around items. Average time is 20 minutes, adjusted for load sizes.

CH 11: Explain two methods of dry heat control.

Incineration - direct exposure to very intense heat (up to 1,870 C with a bunsen burner or up to 6,500 C in furnaces/incinerators) reduces microbes and materials to ashes and gas. In labs - sterilizing inoculating loops. In hospitals and research labs - destroying syringes, needles, culture materials, dressing, bandages, animal carcasses and pathology samples. Its fast and effective sterilizing technique but limited to metal and heat resistant glass and has safety & environmental risks

Hot-air oven - uses electric or gas heat that circulates w/in an enclosed compartment. Sterilization requires 150 C to 180 C for 2 to 4 hours to thoroughly heat an object and destroy endospores. Used for sterilizing items that can withstand long exposure to dry heat.

CH 11 Identify advantages and disadvantages of cold treatment and desiccation.

Cold tx Advantage - slow down growth of microbes in food and cultures during storage. Freezing temp can preserve bacteria, viruses and fungi for long period (used in labs)

Cold tx Disadvantage - cold does not reliably kill most microbes; many survive gradual cooling, refrigeration or freezing. Some pathogens (like Staphylococcus aureus, Clostridium, Streptococcus, and Salmonella) can survive months in the refrigerator. Psychrophiles can still grow slowly and produce toxins even at freezing temperatures.

Desiccation advantage - reduces amt of water available, w/h slows down or stops microbial growth. Useful for preserving food and some microorganism (through method like lyophilization) 

Desiccation disadvantage - many microbes including endospores can survive drying for a very long period. Some pathogens & viruses remain viable in dried secretions, dust, and air.

Not reliable as a disinfection/sterilization method because microbial survival is unpredictable

CH 11 Differentiate between the two types of radiation control methods, providing an application of each.

• Ionizing radiation ejects orbital electrons from atoms causing ions to form. This leads to catastrophic mutations in DNA and damage to proteins that would normally repair cells. It can also cause chemical changes in organelles and produce toxic substances. Ex: include gamma rays, x-rays, and high speed electrons. An application of ionizing radiation is sterilizing medical equipment or preserving food by killing microbes.

• Nonionizing radiation, such as ultraviolet (UV) light, excites atoms by raising them to higher energy states w/o ionizing them. This excitation of nonionizing radiation os disinfecting surfaces, air, and water by using UV light to control microbial growth.

CH 11 Outline the process of filtration, and describe its two advantages in microbial control.

Filtration removes microbes from air & liquids by passing fluid through a filter with pores  small enough to block microorganisms while allowing the liquid to pass through. Filters made from materials like cellulose acetate, polycarbonate, Teflon, or nylon, with pore sizes ranging from coarse to ultrafine. Microbes larger than the pore diameter are trapped on the filter surface, and some filters can even remove viruses and large proteins.

Two Advantages of Filtration in Microbial Control:

1. It allows sterilization of heat-sensitive liquids such as serum, vaccines, drugs, IV fluids, and media without damaging them.

2. It efficiently removes airborne contaminants using HEPA filters in hospital rooms, sterile rooms, and masks, helping control infections like COVID.

CH 11 Identify some common uses of osmotic pressure as a control method

• Preserving meats by curing them with high salts concentrations

• Preserving jellies and similar foods by adding high sugar concentrations. In both cases, the high solute environment creates hypertonic conditions that cause plasmolysis in bacteria, preventing them from multiplying.

CH 11 Name the desirable characteristics of chemical control agents.

halogens, heavy metals, alcohols, phenolic compounds, oxidizers, aldehydes, detergents, and gases

CH 11 Discuss several different halogen agents and their uses in microbial control.

• Halogens: chlorine - kills bacteria, endospores, fungi + viruses; 

  • liquid/gas chlorine: for drinking water, sewage and wastewater

  • Hypochlorites: for cleaning wounds, disinfecting bedding and instruments and sanitizing food equipment, pools and spas

  • Chloramines: used in drinking water, and for treating wounds and skin

• Halogens: iodine - 2% iodine, 2.4% iodide: used on skin as antiseptic

• 5% iodine, 10% iodide: disinfects plastic, rubber tools and blades

• Iodophors (2-10% iodine): used for skin prep before surgery, surgical scrubs, treating burns and disinfecting.

CH 11  List advantages and disadvantages to the use of phenolic compounds as control agents.

Advantage 

• Broad spectrum antimicrobial effects (kills many types of microbes) 

• Can be used as disinfectant and antiseptics 

• Some, like triclosan, were widely used in health care settings

Disadvantage

• Phenol is toxic and irritating to the skin and tissues

• Some phenolics (like triclosan) can lead to microbial resistance with overuses 

• Not all phenolics compounds are safe for regular consumer use

CH 11 . Explain the mode of action of alcohols and their limitations as effective antimicrobials.

• Alcohol dissolves membrane lipids, disrupts membrane integrity and denature proteins (only in 50-95% alcohol water solutions). Water helps protein coagulate, so 70% alcohol is more effective than 100%. At 100% alcohol dehydrates cells but does not effectively kill microbes.

• Limitations : alcohol evaporates quickly, reducing contact time needed for microbial action. Not effective at killing endospores. Isopropyl alcohol can be toxic if inhaled in large amts. Works best on skin and small object, not on large surfaces or heavily soiled areas

CH 11 Pinpoint the most appropriate applications of oxidizing agents.

• Disinfection of skin, wounds and surfaces (bcuz its bactericidal, virucidal and fungicidal) 

• Sterilization of medical and dental instruments (at higher concentrations, because it can be sporicidal) 

• Used in antiseptics for skin cleansing and wound care

CH 11 Define The term surfactant, and explain this antimicrobial's mode of action.

• A surface-active agent that forms a water-soluble interface. Examples: detergents, wetting agents, dispersing agents, and surface tension depressants.

• In microbial control surfactants like quaternary ammonium compounds (quats) work by binding their positive charged end to the negative charged surface proteins, while unchanged hydrocarbon chai disrupts cytoplasmic membrane. This causes the membrane to lose its selective permeability leading to cell death.

CH 11 Identify examples of some heavy metal control agents and their most common applications

• Silver nitrate (AgNO₃): prevent eye infection in newborn, tx mouth ulcers and root canals

• Silver sulfadiazine ointment: used in burn wound to prevent infection

• Colloidal silver preparations: used as mild germicides for mouth, nose, eyes and vagina

• Mercury compounds: Historically used, now limited due to toxicity.

• Silver-infused surfaces and textiles: incorporated in items like catheters, stethoscopes, plastic and fabrics to control microbial growth

CH 11 Discuss the advantages and disadvantages of aldehyde agents in microbial control

Advantages: Glutaraldehyde is rapid, broad-spectrum, and can sterilize by destroying endospores. Retains potency in the presence of organic matter, non corrosive, less irritating than formaldehyde. Ortho-phthalaldehyde (OPA) is stable, non irritating, fast-acting, and effective against many microbes.

Disadvantages: Glutaraldehyde is unstable with increased pH and temperature. Formaldehyde is toxic, irritating, slow-acting, and classified as a carcinogen. OPA does not reliably destroy endospores and can stain proteins.

CH 11  Identify applications for ethylene oxide sterilization

Ethylene oxide used to sterilize heat sensitive medical equipment and materials, including plastics and delicate instruments. It applied in specially controlled ETA sterilizers (chemiclaves for items that cant withstand heat/liquid chemical sterilization.

CH 12 1. State the main goal of antimicrobial treatment

Administer a drug to an infected person that destroys the infective agent without harming the host’s cells

CH 12: 2. Identify sources of the most commonly used antimicrobial drugs.

• Streptomyces and Bacillus in bacteria.

• Penicillium and Cephalosporium from molds

CH 12: Summarize two methods for testing antimicrobial susceptibility.

- Kirby Bauer Disk Diffusion test: if the bacterium is sensitive to a drug, a zone of inhibition develops around the disk. The larger the zone, the greater the bacterium's sensitivity to the drug is.

- E-test diffusion test (epsilometer test) which is a gradient diffusion method that determines antibiotic sensitivity and estimates the minimal inhibitory concentration.

CH 12: Define therapeutic index, and identify whether a high or a low index is preferable in a drug.

• The ratio of the dose of the drug that is toxic to humans to its minimum effective (therapeutic) dose. 

• The closer these two figures are to each other (the smaller the ratio), the greater potential for toxic drug reactions

        - TI of 1.1 is a riskier choice than a TI of 10

        - When drugs have similar MICs, the drug with the highest TI has the widest margin of safety

CH 12 Explain the concept of selective toxicity.

an effective antimicrobial agent that must be more toxic to a pathogen than a pathogens host; drugs with excellent selective toxicity block the synthesis of the bacterial cell wall (penicillins); human cells lack the chemical peptidoglycan and are unaffected by the drug

CH 12. Describe the five major targets of current antimicrobial agents, and list major drugs associated with each.

1. inhibition of cell wall synthesis

2. Inhibition of protein synthesis

3. Inhibition of nucleic acid. replication

4. Injury to plasma membrane

5. Inhibition of essential metabolite synthesis

CH 12 Identify which categories of drugs are most selectively toxic, and explain why.

Antibacterial drugs (Penicillins, Cephalosporins, Tetracylines, etc)  are the most selectively toxic. WHY? They target parts of bacteria (like cell walls or bacterial ribosomes) that human cells don’t have, so they harm the bacteria but not us.

CH 12 Distinguish between drug toxicity and allergic reactions to drugs.

Allergic- heightened immunosensitivity, drugs acts as an antigen

Toxicity- foreign chemicals harm human tissue

CH 12 Define the term superinfection, and summarize how it develops in a patient.

A superinfection is a new infection that happens while you're already being treated with antibiotics.
How it happens: Antibiotics kill good bacteria too, so bad ones (like resistant ones or fungi) take over.

CH 12 Distinguish between broad-spectrum and narrow-spectrum antimicrobials, and explain the significance of the distinction.

• Broad-spectrum = Kills many types of microbes (both Gram+ and Gram–).

• Narrow-spectrum = Targets specific microbes.

Why it matters:
Broad-spectrum is good when you don’t know the exact cause, but it can kill good bacteria too. Narrow-spectrum is better when you know the cause—it’s safer for your good microbes.

CH 12 Trace the development of ß-lactam antimicrobials, and identify which microbes they are effective against.

ß-lactam antibiotics include penicillins and cephalosporins.

They work against: Mostly Gram-positive bacteria, and some have been modified to work on Gram-negative too.

They stop bacteria from building their cell walls.

CH 12 Describe the action of ß-lactamases, and explain their importance in drug resistance.

ß-lactamases are enzymes made by some bacteria.

They break down ß-lactam antibiotics, making the drugs useless.

Why is it important? It’s a major cause of antibiotic resistance.

CH 12 List examples of other ß-lactam antibiotics.

• Penicillins 

• Cephalosporins 

• Carbapenems 

• Monobactams

CH 12 Describe common cell wall antibiotics that are not in the ß-lactam class of drugs.

• Vancomycin – Inhibits peptidoglycan synthesis (used for Gram-positive bacteria).

• Bacitracin – Blocks transport of peptidoglycan precursors.

• Isoniazid – Targets mycolic acid synthesis in Mycobacterium tuberculosis.

Ethambutol – Also used against Mycobacterium, affecting cell wall integrity.

CH 12 Identify the targets of several antibiotics that inhibit protein synthesis.

• Tetracyclines – Bind 30S subunit; block tRNA binding.

• Aminoglycosides (e.g., streptomycin) – Bind 30S; cause misreading of mRNA.

• Macrolides (e.g., erythromycin) – Bind 50S; block translocation.

• Chloramphenicol – Inhibits peptide bond formation at 50S.

Oxazolidinones – Block formation of the initiation complex at 50S.

CH 12 Identify the cellular target of quinolones, and provide two examples of these drugs.

Target: DNA gyrase and topoisomerase IV (enzymes needed for DNA replication).

Examples:

• Ciprofloxacin

• Levofloxacin

CH 12 Name two drugs that target the cellular membrane.

• Polymyxins (e.g., polymyxin B) – Disrupt Gram-negative bacterial membranes.

Daptomycin – Targets Gram-positive cell membranes, causing ion leakage.

CH 12 Describe the unique problems in treating biofilm infections.

• Biofilms protect microbes with a sticky matrix.

• Bacteria in biofilms grow slower and resist antibiotics.

• They often exchange resistance genes.

• The immune system has difficulty reaching microbes inside biofilms.

CH 12 Name the four main categories of antifungal agents, and provide one example of each.

• Polyenes –  Amphotericin B

• Azoles –  Fluconazole

• Echinocandins – Caspofungin

Allylamines – Terbinafine

CH 12 List two antiprotozoal drugs and three antihelminthic drugs used today.

Antiprotozoals:

• Metronidazole – Used for Giardia, Entamoeba, Trichomonas.

• Chloroquine – Used for Plasmodium (malaria).

Antihelminthics:

• Mebendazole – Inhibits worm microtubules.

• Ivermectin – Paralyzes worms.

• Praziquantel – Disrupts membranes of flatworms and flukes.

CH 12 Describe three major modes of action of antiviral drugs.

1. Inhibit viral entry – Enfuvirtide for HIV.

2. Inhibit nucleic acid synthesis – Acyclovir for herpes viruses.

3. Inhibit viral assembly/release – Oseltamivir (Tamiflu) for influenza.

CH 12 Discuss two possible ways that microbes acquire antimicrobial resistance.

1. Spontaneous mutation – Random DNA changes during replication.

2. Horizontal gene transfer – Bacteria acquire resistance genes via:

   • Conjugation (plasmids)

   • Transformation

   • Transduction (bacteriophages)

CH 12 List five cellular or structural mechanisms that microbes use to resist antimicrobials.

1. Drug inactivation – ß-lactamases destroy penicillins.

2. Altered target – changes in ribosome structure.

3. Efflux pumps – Pump drug out of cell.

4. Decreased permeability – Altered porins block drug entry.

Bypass pathways – Microbe uses alternative enzymes or pathways.

CH 12 Discuss at least three novel antimicrobial strategies that are under investigation.

• Phage therapy – Using viruses to target specific bacteria.

• CRISPR-based antimicrobials – Editing bacterial DNA to kill or disarm pathogens.

Quorum sensing inhibitors – Block communication among bacteria, preventing virulence.