Chapter 8 Notes PDF

# Chapter 8 Notes * **Metabolism:** sum of chemical reactions in the body that are necessary to maintain homeostasis. * **Two types of metabolism:** * **Anabolism:** building up of macromolecules to build structural components and perform normal functions. * **Catabolism:** breaking down of...

# Chapter 8 Notes * **Metabolism:** sum of chemical reactions in the body that are necessary to maintain homeostasis. * **Two types of metabolism:** * **Anabolism:** building up of macromolecules to build structural components and perform normal functions. * **Catabolism:** breaking down of macromolecules to produce energy. * **Enzymes in Metabolism:** * Enzymes are biological catalysts. * Increase the rate of chemical reactions by lowering energy of activation. * Do not become part of the products. * Are not consumed or altered in the process. * **Cofactors:** supporting the work of enzymes. * **Coenzymes:** * Work in conjunction with an enzyme. * Organic molecules - many derived from vitamins. * **Denaturation:** * Weak bonds that maintain the native shape of the apoenzyme are broken. * This causes distortion of the enzyme's shape. * Prevents the substrate from attaching to the active site. * **Constitutive Enzymes:** present in a cell in constant amounts. The addition of more substrate doesn't increase the amount of these enzymes. * **Regulated Enzymes:** concentration in a cell increases or decreases in response to substrate levels. * **Controls on Enzyme Synthesis:** * Can be accomplished by induction or repression of enzyme. * **Energy is mostly stored as ATP.** * **Oxidation-reduction (redox):** electron donor paired with electron acceptor as energy is released and captured. # Chapter 8 Notes * **Metabolism:** Uses enzymes to catabolize organic molecules to precusor molecules that cells then use to anabolize larger, more complex molecules. * **Three Pathways of Primary Catabolism:** * Glycolysis * Kreb's Cycle * Respiratory chain - electron transport and oxidative phosphorylation. * **Aerobic respiration:** relies on oxygen. * **Anaerobic respiration:** uses $NO3^-$, $SO4^2$, $CO3^2$,and other oxidized compounds as final electron acceptors. * **Fermentation:** incomplete oxidation of glucose. * Oxygen isn't required. * **Glycolysis:** * All 3 metabolic strategies begin with glycolysis. * Glucose oxidized into 2 molecules of pyruvic acid. * 2 NADH and 2 ATP generated. * **The Electron Transport Chain:** * A chain of special redox carriers. * Embedded in the cytoplasmic membrane in bacteria. * **Catabolism of Noncarbohydrates:** * Complex polysaccharides broken into component sugars, which can enter glycolysis. * Lipids broken down by lipases: * Fatty acids undergo beta oxidation, whose products can enter the Kreb's cycle as acetyl CoA. * Proteins broken down into amino acids by proteases: * Amino groups are removed through deamination. * **Component parts of bacteria are being synthesized on a continuous basis.** * **Catabolism is also taking place as long as nutrients are present and the cell is nondormant.** * **Catabolic processes provide all of the energy for complex building reactions.** # Chapter 7 Notes * **Bioelements:** basic elements all living things need. * **Essential nutrient:** any substance that must be provided to an organism (cannot make it on its own). * **Macronutrients:** Required in relatively large quantities and play principal roles in cell structure and metabolism. * Compounds that contain carbon, hydrogen, and oxygen. * **Micronutrients:** Present in much smaller amounts and are involved in enzyme function and maintainence of protein structure. * Also known as trace elements. * **Inorganic nutrients:** atoms/molecules other than carbon and hydrogen. * **Organic nutrients:** contain carbon and hydrogen. * **Most chemical elements available to the cell as compounds and not as pure elements.** * **Potassium $(K)$:** essential to protein synthesis and membrane function. * **Sodium $(Na)$:** important for certain types of cell transport. * **Calcium $(Ca)$:** stabilizer of cell wall and endospores of bacteria. * **Magnesium $(Mg)$:** component of chlorophyll and a stabilizer of membranes and ribosomes. * **Iron $(Fe)$:** important component of the cytochrome proteins of cell respiration. * **Zinc $(Zn)$:** essential regulatory element for eukaryotic genetics. # Chapter 7 Notes * **Carbon Source** * **Heterotroph:** microbe that must obtain its carbon in an organic form. * **Autotroph:** microbe that uses inorganic $CO2$ as its carbon source. * **Energy (ATP) Source:** * **Phototroph:** microbe that photosynthesizes. * **Chemotroph:** microbe that gets its energy from chemical reactions. * **Passive transport:** does not require energy. * **Hypotonic solution:** net diffusion of water is into the cell; this swells the protoplast and pushes it tightly against the wall. Wall usually prevents cell from bursting. * **Hypertonic solution:** water diffuses out of the cell and shrinks the cell membrane away from the cell wall. # Temperatures for Microbial Growth: * **Minimum temperature:** the lowest temperature that permits a microbes continued growth and metabolism; below this temperature, its activities stop. * **Maximum temperature:** the highest temperature at which growth and metabolism can proceed before proteins are denatured. * **Optimum temperature:** best temperature that promotes the fastest rate of growth and metabolism. * **Psychrophiles:** cold loving - optimum temp. below 15°C. * **Psychotrophs:** optimum temp. between 15°C and 30°C. # Chapter 7 Notes * **Mesophiles:** moderate-temp loving - optimum temp between 20°C and 40°C. * **Thermophiles:** heat-loving - optimum temp above 45°C. * **Aerobes:** can use gaseous oxygen in their metabolism and possess the enzymes needed to process toxic oxygen products. * **Obligate aerobe:** An organism that cannot grow without oxygen. * **Microaerophiles:** are harmed by normal atmospheric concentrations of oxygen but require a small amount of it in metabolism. * **Facultatives anaerobes:** do not require oxygen for metabolism but use it when it is present. * **Anaerobes:** lack the metabolic enzyme systems for using oxygen in respiration. * **Obligate anaerobes:** also lack the enzymes for processing toxic oxygen and die in its presence. * **Aerotolerant anaerobes:** don't utilize oxygen but can survive and grow to a limited extent in its presence. * **Acidophiles:** grow in acidic environments. * **Alkaliphiles:** grow optimally at pH above 8.5. * **Halotolerant/osmotolerant:** withstand up to 20% (Staphylococcus). * **Halophiles/Osmophiles:** require high salt concentrations. * **Biofilms:** mixed communities of bacteria and other microbes that are attached to a surface and each other in complex organized communities. # Chapter 7 Notes * **Binary fission:** one cell becomes two. * **Generation time or doubling time:** time required for a complete fission cycle, from parent cell to two daughter cells. * **Generation:** increases the population by a factor of two. * **Growth curve:** a predictable pattern of a bacterial population growth in a closed system can be measured. * **The lag phase:** is a "flat" period of growth due to Newly inoculated cells that require a period of adjustment enlargement, and synthesis. * **Exponential growth (logarithmic or log) phase:** * Growth curve increases geometrically. * Will continue as long as cells have adequate nutrients and the environment is favorable. * **Stationary phase.** * **Death phase.** * **Direct cell count:** measured microscopically. * **Coulter counter:** electronically scans a fluid as it passes through a tiny pipette. * **Flow cytometer:** works similarly to a Coulter counter, but can measure cell size and differentiate between live and dead cells. # Chapter 11 Notes * **Contaminants:** are microbes present at a place and time that are undesirable or unwanted. * **Most decontamination methods employ either physical agents or chemical agents.** * **Microbes are divided into 3 groups:** * Highest resistance * Moderate resistance * Least resistance. * **Sterilization:** is the process that destroys or removes all viable microorganisms, including viruses. * **Stasis and static means to stand still.** * **Microbistasis:** is when microbes are temporarily prevented from multiplying but not killed. * **Bacteriostatic agents:** prevent the growth of bacteria. * **Disinfection:** is the use of a physical process or a chemical agent to destroy vegatative pathogens but not bacterial endospores. * **Antiseptics:** are applied directly to exposed skin. * **Sanitization:** refers to any cleansing technique that removes debris, soil, microorganisms, and toxins. * **The destructive effects of chemical and physical agents occur at the cellular and molecular level.** * **In most circumstances, microbial death is defined as the permanent loss of reproductive capacity, even under optimal growth conditions** * **Surfactants:** work as microbicidal agents because they lower the surface tension of cell membranes. * **Microbial life depends upon an orderly and continuous supply of proteins to function as enzymes and structural molecules.** * **Any chemical that blocks this process can affect function and survival.** # Chapter 11 Notes * **In general, denaturation occurs when the bonds that maintain the secondary and tertiary structure of the protein are broken.** * **Breaking these bonds will cause the protein to unfold or create random, irregular loops and coils.** * **Microorganisms have adapted to a tremendous diversity of habitats on earth, some having severe conditions of temperature, moisture, pressure, and light.** * **Most common among antimicrobial physical agents is heat.** * **Others include radiation and filtration.** * **Moist heat and dry heat differ in their modes of action as well as their efficiency** * **Higher temp. allows shorter exposure time, lower temp. requires longer exposure time.** * **A combination of these 2 variables constitutes the thermal death time: shortest length of time required to kill all test microbes at a specified temp.** * **Thermal death point:** defined as the lowest temp-required to kill all microbes in a sample in 10 mins. * **Pasteurization:** is a technique of applying heat to consumable liquids to kill potential agents of infection and spoilage, while at the same time retaining the liquid's flavor and food value. * **Cold merely retards the activities of most microbes.** * **Irridation:** the application of radiant energy for diagnosis, therapy, disinfection, or sterilization. * If the radiation ejects orbital electrons from an atom, it causes ions to form: this type of radiation is termed ionizing radiation. * **Nonionizing radiation**, best exemplified by UV, excites atoms by raising them to a higher energy state, but it doesn't ionize them. * **Drugs, vaccines, medical instruments, and other delicate materials can be irradiated without harming them.** * **Ultraviolet radiation is usually aimed more at disinfection.** # Chapter 11 Notes * **Filtration** is an effective method to remove microbes from air and liquids. * **Intermediate-level germicides:** kill fungal (but not bacterial) spores, resistant pathogens, and viruses. * **Halogens:** a group of related chemicals with antimicrobial applications. * **Alcohol's mechanism of action depends in part upon its concentration.** * **Alcohol tends to inactivate enveloped viruses more readily than nonenveloped viruses because of the surfactant effect on the envelope.** * **The germicidal effects of hydrogen peroxide are due to the direct and indirect actions of oxygen. Oxygen forms hydroxyl free radicals.** * **Glutaraldehyde:** is rapid and broad-spectrum, and is officially labeled as a sterilant and high-level disinfectant. * **Ethylene oxide (ETO):** is a very strong alkylating agent. * Reacts vigorously with functional groups of DNA and proteins. * Blocks both DNA replication and enzymatic actions. * **Quaternary ammonium compounds:** * Activity is greatly reduced in the presence of organic matter. * Require alkaline conditions to function. * Rated only low to moderate-level disinfection. # Chapter 12 Notes * **The goal of antimicrobial chemotherapy is simple: administer to an infected person a drug that destroys the infectious agent without harming the host's cells** * **Difficult goal to achieve** * **Antibiotics:** are substances produced by the natural metabolic processes of certain microorganisms that can inhibit or destroy other microorganisms. * **Drugs should be selectively toxic, which means they can kill or inhibit the growth of microbes without Simultaneously damaging host tissues.** * **The cell walls of most bacteria contain a rigid girdle of peptidoglycan, which protects the cell against rupture from hypotonic environments.** * Must constantly synthesize new peptidoglycan. * **Polymyxins:** interact with membrane phospholipids and cause leakage of proteins and nucleic acids, particularly in gram-negative bacteria. * **Daptomycin:** shows selectivity for gram-positive cells. * **Antimicrobial drugs** interfere with nucleic acid synthesis by blocking synthesis of nucleoticles, inhibiting replication, or stopping transcription. * **Several antimicrobials inhibit DNA synthesis.** * **Most drugs that inhibit protein synthesis react with the ribosome-mRNA complex.** * **Penicillin G:** was the first antibiotic. * Narrow spectrum, can't be given by mouth. * **Polymyxins:** a mixture of antibiotic polypeptides from *Bacillus polymyxa* that are particularly effective against gram-negative bacteria. * Toxic to the kidney. * **Rifampin:** disrupts nucleic acids by blocking the action of RNA polymerase, preventing transcription. * **Tetracyclines:** a group of broad-spectrum antibiotics with a complex 4-ring structure. # Chapter 12 Notes * **Tetracycline's action:** is to bind to ribosomes and blocking protein synthesis. * **Sulfonamide:** antimicrobial drugs that interfere with the essential metabolic process of bacteria and some fungi : also known as sulfa drugs. * Block synthesis of folic acid by bacteria * **Ivermectin:** is a broad-spectrum antiparasitic used in the treatment of round worm infection and lice. * **Major modes of action include:** * Barring penetration of the virus into the host cell. * Blocking replication, transcription, and / or translation of viral genetic material. * Preventing the normal maturation of viral particles. * **One of the most important targets is the reverse transcriptase (RT) enzyme that HIV brings into the host cell.** * **Reverse Transcriptase:** the enzyme possessed by retroviruses that carries out the reversion of RNA to DNA - a form of reverse transcription. * **Interferon:** is a glycoprotein produced primarily by fibroblasts and leukocytes in response to various immune stimuli. * **Drug Resistance:** an adaptive response in which microorganisms begin to tolerate an amount of drug that had previously been inhibitory. * **Many bacteria possess multi-drug resistant (MDR) pumps that actively transport drugs and other chemicals out of cells.** * **MDR pumps are proteins encoded by plasmids or chromosomes.** * **MDRs lack selectivity** * **About 60% of infections involve biofilms, complex communities of microorganisms growing within an extracellular matrix.** # Chapter 12 Notes * **The major side effects of drugs falls into one of 3 categories: direct damage to tissues through toxicity, allergic reactions, and disruption of the body's microbiota.** * **Damage can be short term and reversible or permanent.** * **Superinfection:** an infection occurring during antimicrobial therapy that's caused by an overgrowth of drug-resistant microorganisms. * **The Kirby- Bauer technique:** is an agar diffusion test that provides useful data on antimicrobial susceptibility. * Less effective for bacteria that are anaerobic, highly fastidious, or slow-growing. * **More sensitive and quantitative results can also be obtained with tube dilution tests.** * **The smallest concentration of drug in the series that visibly inhibits growth is called the minimum inhibitory concentration (MIC).** * Useful in determining the smallest effective dosage of a drug and in providing a comparative index against other antimicrobials. * **When antimicrobial treatment fails, usually due to: ** * The inability of the drug to diffuse into that body compartment. * A few resistant cells in the culture that didn't appear in the sensitivity test. * An infection caused by more than one pathogen (mixed), some of which are resistant to the drug. * **If therapy does fail, a different drug, combined therapy, or a different method of administration must be considered.**