Microbiology Final Exam Part I
What are the 4 main families of organic chemicals? What elements each of these families are composed of and the name of the specific type of bonds that hold these molecules together?
Carbohydrates: C, H, O; glycosidic Lipids: C, H, O; ester Nucleic acids: C, H, O, N, S, P; hydrogen Proteins: C, H, O, N & some S; peptide
What are exoenzymes and endoenzymes and explain why bacterial exoenzymes and endoenzymes can be important in infectious diseases
-Exozymes: enzymes that work outside the cell (extracellular enzymes) -Endozymes: enzymes that work inside the cell (intracellular enzymes) -toxins are enzymes and can cause disease
What antibacterial drug group targets DNA replication and what specific enzyme does this group of drugs target
Fluoroquinolones: inhibits TOPOISOMERASE & DNA GYRASE so bacterial chromosome REMAINS SUPERCOILED which prevents DNA replication
List three ways you can grow a virus
in animals, embryonic eggs, and in human/animal cell culture
What antibacterial drug group targets bacterial plasma membranes and how does this group of drugs adversely effect bacteria?
polymixins: detergent-like effect which disrupts phospholipid bilayer= particularly effective against Gram negative bacteria
Bioenhancer
compound that allows a specific bacterial population to increase
With respect to protozoa and helminths, explain what an intermediate and definitive host is?
definitive host: The host that carries the ADULT or SEXUALLY MATURE FORM of a protozoa or helminth intermediate host: The host that carries the LARVAL or ASEXUAL STAGE of a protozoa or helminth
What is the major role(s) of the lymphatic system?
used to transport lymphocytes (i.e., B cells and T cells) and acts as a "filtering system" against impurities and invading pathogens
What specific types of leukocytes are associated with acquired/adaptive immunity?
lymphocytes- B cells and T cells
Explain the basic/general life cycle of protozoa and define the two life forms protozoa may exist as.
-ALL protozoa have a trophozoite form -under hostile conditions= encystment= cyst form -when better conditions return: excystment= trophozoite
List the five types of viral infections and provide an example (name of a virus or viral disease) for each
-Acute with low mortality (common cold) -Acute with high mortality (hemorrhagic fever) -Chronic (hepatitis) -latent (shingles) -oncogenic (HPV)
Explain/describe how an intracellular microbe can be destroyed by the immune system
-An infected cell will break down some of the pathogen's antigens, which are considered NON-SELF or FOREIGN antigens -NON-SELF or FOREIGN antigens will combine with a host protein termed the MHC complex and be presented on the surface of the infected cell as a MHC+antigen complex -receptors on the surface of a cytotoxic T cell will recognize and specifically bind to the MHC+antigen complex on the surface of an infected cell -the binding between the cytotoxic T cell and the infected cell will cause ACTIVATION of the cytotoxic T cell -next time ACTIVATED cytotoxic T cell encounters a cell infected with the same pathogen it will recognize and bind to the MHC+antigen complex on the infected cell's surface -once bound the ACTIVATED cytotoxic T cell will secrete TOXIC PROTEINS directly at the infected cell that will KILL the cell as well as the pathogens inside the cell
What are the similarities & differences between the following structures in prokaryotes and eukaryotes: flagella, cell wall, cytoplasmic membrane and ribosomes.
-Both bacterial & eukaryotic cells may possess flagella and the flagella have the same function (locomotion), but otherwise extremely different (bacterial flagella spins) (eukaryotic waves) -prokaryote cell walls contain peptidoglycan while eukaryote typically have no cell wall and definitely not peptidoglycan -both have a selectively permeable plasma membrane but prokaryotes do not contain sterols while eukaryotes do -prokaryote ribosomes are smaller 70S ribosomes that are free within the cytoplasm while eukaryotic ribosomes are larger 80S ribosomes that are either free within the cell or membrane-bound
What are the four major external structures a bacterium may possess and what is the function of each?
-Flagella: long filamentous appendage(s) that provides locomotion -fimbriae: surface "bristle-like" appendages that are numerous and cover the entire bacterial surface and are shorter and thinner than flagella; allow for attachment (adherence) -pilli: surface appendages that are longer than fimbriae but fewer in number; associated with motility and sex/DNA transfer -glycocalyx: sticky coating composed of polysaccharides and/or proteins that surrounds the bacteria (capsule- attachment and protection against phagocytosis) or (slime layer-biofilm)
List the nine general types of chemical compounds that can be used for disinfection and indicated which of these compounds can be categorized as sterilizing agents
-Halogens (not sterilizing) -Phenols & Phenol Derivatives (not sterilizing) -Bisbiguanides (not sterilizing) -Alcohols (not sterilizing) -Heavy Metals (not sterilizing) -Surfactants (not sterilizing) -Aldehydes (sterilizing agent) -Peroxygens (sterilizing agent) -Ethylene Oxide Gas (sterilizing agent)
Explain why Anton van Leeuwenhoek is considered the father of microbiology and explain either how Louis Pasteur disproved abiogenesis or his germ theory of disease?
-Leeuwenhoek the first person to observe and document microbes -Pasteur's S-neck experiment proved that when beef broth was undisturbed with an S-neck flask there was no microbial growth
Define the following: neutrophiles, acidophiles and alkaliphiles. What category do most human pathogens fall into?
-Neutrophiles: For optimal growth of MOST bacteria pH 6.5-7.5 -acidophiles: can survive and grow under acidic conditions (pH <5.5) -alkaliphiles: can survive and grow under alkaline/basic conditions (pH 8-10)
What are the six organelles that eukaryotes can possess and what is the basic function of each?
-Nucleus: contains the cell's genetic information -Rough ER: protein synthesis -smooth ER: lipid synthesis -Golgi: transportation hub/central post office -mitochondria: site of cellular respiration -used for digestion of "food" taken up by the cell, destruction of microorganisms and removal of damaged organelles
Describe three ways that antibodies can protect us from a pathogen and infection
-Opsonization (by coating pathogen with antibodies more effectively ingested by phagocytic cells) -activation of complement (complement components can bind to antibodies attached to a bacterium and form a complex that will make pores in the bacterial membrane= bacterial cell lysis will occur) -neutralization (the binding of antibodies to antigens of the surface of a pathogen (bacterium, fungus, protozoa, helminth or virus) or a toxin, which PREVENTS the pathogen/toxin from BINDING to host cells)
What are the overall goals of wastewater treatment? What occurs during primary and secondary treatment of wastewater, how are microorganisms used in this process and what is required before wastewater can be released into the environment?
-Sewage treatment is the removal of harmful materials and organic matter from sewage and to remove pathogens -stage 1: Sewage is passed through a series of SCREENS to remove large debris, rocks and grit -stage 2: The wastewater is moved into SEDIMENTATION or SETTLING tanks. Solids still in the water will settle to the bottom of the tank and can then be removed. -In the presence of OXYGEN, AEROBIC microbes can breakdown the dissolved organic matter in the water in an aeration tanks or in trickling systems microorganisms form a biofilm on rocks to degrade organic material -Microorganisms and BOD must be significantly decreased before release into the environment
Explain how sludge from wastewater treatment is processed and the two key components that result from this process.
-Sludge can be "processed" in large tanks almost devoid of oxygen termed anaerobic sludge digesters -Under anaerobic conditions a different population of microbes in the sludge can grow and degrade the organic solids into soluble substances (Stabilized dry sludge, termed biosolids, can be used as fertilizer/soil conditioner) and methane gas (a biogas that can be used as a biofuel)
Define the terms sterilization, disinfection, antisepsis, degermation and sanitization
-Sterilization: the COMPLETE removal/destruction of ALL microbial life (including bacterial endospores) -disinfection: the destruction of MOST but NOT all microbial life on INANIMATE surfaces through the use of chemicals, termed DISINFECTANTS, or heat -antisepsis: the destruction of MOST but NOT all microbial life on LIVING skin or tissue through the use of chemicals termed ANTISEPTICS -degermation: gentle scrubbing and/or swabbing of living tissue (e.g. the skin) with chemicals (antiseptics) to REDUCE the number of microorganisms -sanitization: the cleaning of inanimate objects with chemical disinfectants or heat in order to REDUCE the number of microbes and achieve safe public health levels
What are the general characteristics of trematodes, cestodes and nematodes?
-Trematodes (flukes):flat with suckers to allow the organism to adhere to surfaces; most are hermaphrodites; all infect mollusks as part of their life cycle; crustaceans are intermediate host and humans are definitive -Cestodes (tapeworms): flat with suckers and hooks on the scolex (i.e., head) to allow for adherence to surfaces; body is in segmented termed proglottids; all are hermaphrodites; all are intestinal parasites; cattle are intermediate host with humans as definitive host -Nematodes (roundworms): non-segmented and cylindrical worms with tapered ends; most are dioecious; complete digestive tract; includes pinworms (eggs are infectious stage) and heartworms (larvae are infectious stage); humans are definitive and intermediate host
What Is peptidoglycan, what is it composed of and describe its overall structure/arrangement
-a macromolecule network composed of repeating disaccharides attached by polypeptides to form a lattice around the cell -The amino acid "tail" that hangs off a NAM sugar is either directly linked via a PEPTIDE CROSS BRIDGE to the amino acid "tail" from another NAM sugar
What can a vaccine be composed of and what is the goal of vaccination?
-a whole microbe that has been killed/inactivated -a whole living microbe that has lost its virulence -a part of a microbe or a compound secreted by a microbe -The goal of a vaccine is to PROTECT against disease by stimulating the immune response without actually having to acquire the disease
Compare aerobic respiration, anaerobic respiration and fermentation in prokaryotes in terms of whether the oxygen is required, what the final electron acceptors are for each pathway and the number of ATP produced from 1 molecule of glucose
-aerobic respiration: O2 required; O2 is the final electron acceptor; makes 38 ATP/glucose -anaerobic respiration: O2 not required; An INORGANIC MOLECULE (other than oxygen) is the FINAL ELECTRON ACCEPTOR (nitrate/sulfate/etc.); makes 5-36 ATP/glucose -fermentation: O2 not needed; organic molecules like pyruvate are the final electron acceptor; makes 2 ATP/glucose
Define anabolism and catabolism and explain the relationship between anabolic and catabolic reactions and ATP.
-anabolic: building up from small molecules to make more complex compounds; usually involves DEHYDRATION reactions (release of water as bonds formed); requires energy so ENDERGONIC reactions (energy requiring) -catabolic: breaking down complex compounds into small molecules; usually involves HYDROLYTIC reactions (using water to break chemical bonds); releases energy so EXERGONIC reactions (energy releasing)
Describe the differences between the infectious cycle of an animal virus, a plant virus and a bacteriophage
-animal virus can release by budding or lysis -plant virus can only release by lysis because of cell wall -animal virus can enter by membrane fusion or cell mediated endocytosis -Plant viruses enter a plant cell at an open wound or via a plant parasite or insect that carries the virus -bacteriophage: lytic and lysogenic cycle -uncoating not required for bacteriophage
What is an antigen and what are antibodies?
-antigen: any cell (bacteria, fungi, mold, protozoa, helminth), particle (virus) or protein (e.g., toxin or adhesin) that can induce an immune response -antibodies are PROTEINS that structurally resemble the letter Y -the "arms" of the antibody are the most important parts of the molecule since these contain the antigen-binding sites
What are the two major structural differences between bacteria and Archaea?
-archaea have hami used for attachment -bacterial cell wall contains peptidoglycan while archaea cell wall does not
What does it mean if an antimicrobial drug has broad spectrum activity or narrow spectrum activity? What is prophylaxis?
-broad: effective against a WIDE number/variety of microorganisms -narrow: effective against a LIMITED number/variety of microorganisms -prophylaxis: Antimicrobial agents can be used to prevent the RISK of an infection
What are the three ways by which bacteria can transfer genetic information and briefly explain each?
-conjugation: the transfer of genetic material by direct contact; the donor bacterium transfers a COPY of the mobile plasmid to the recipient bacterium through a MATING BRIDGE that forms between the two bacteria; after a copy of the plasmid has moved into the recipient bacterium the mating bridge is broken and the sex pilus retracts -transformation: nonspecific acceptance of small fragments of DNA from the surrounding environment by a bacterial cell -transduction: bacteriophage serves as a carrier of DNA from a donor bacterium to a recipient bacterium (general: lytic cycle) (specific: lysogenic cycle)
What are the six major internal bacterial structures? Which of these structures are required and possessed by all bacteria and which structures are "optional" (i.e., not possessed by all bacteria)?
-cytoplasm, nucleoid, bacterial chromosomes, plasmids, ribosomes, inclusions, endospore -plasmids, inclusions, and endospore are optional
Explain, in general terms, how an enzyme works and what factors can influence an enzyme's activity
-enzyme: proteins that increase the rate of a chemical reaction -binds to the active site to lower the activation energy -temperature, pH, and substrate concentration influence and enzyme's activity
What are three general properties of viruses?
-extremely small particles -All are obligate intracellular parasites (requires a living host cell to replicate in) -Very simple structure (nucleic acid enclosed in a protein shell)
Describe the cell wall of a Gram positive bacterium. Describe the cell wall of a Gram negative bacterium. Which type of bacteria (Gram positive or Gram negative) possess teichoic acid, lipopolysaccharide and porins?
-gram positive: THICK layer of peptidoglycan and plasma membrane ("inner" membrane); TEICHOIC ACID ONLY associated with Gram positive cell walls gives more rigidity to the cell wall and can promote binding to certain proteins -gram negative: "OUTER" plasma membrane (phospholipid bilayer); THIN layer of peptidoglycan ; PERIPLASMIC SPACE (contains a gel-like matrix); "INNER" plasma membrane (phospholipid bilayer);LIPOPOLYSACCHARIDE found ONLY in the OUTER MEMBRANE of Gram negative cell walls, helps provide cell wall rigidity; lipid portion if released is TOXIC to humans; PORINS found ONLY in the OUTER MEMBRANE of Gram negative cell walls, form channels which allow molecules to pass through
Explain what a closed growth system is. Diagram the four phases that occur when a bacterium is grown in a closed growth system and explain what is happening at each phase.
-growth in a system in which no nutrients are added AND NO waste products are removed -lag: "adjustment" time to get use to the new environment; bacteria are metabolically active but not growing at this time (straight horizontal line) -log: maximum rate of cell division, exponential growth & constant generation time (exponential = diagonal line); exponential growth will continue as long as an adequate supply of nutrients is available -stationary: GROWTH RATE EQUALS DEATH RATE (straight horizontal line); fewer nutrients available and build up of waste products -death: no nutrients remain and waste products at toxic levels; growth stops and exponential death begins (exponential = diagonal line)
List seven physical methods for controlling microbial growth and indicate how effective each method is in sterilization
-heat (can be used for sterilization) -low temp (cannot be used for sterilization) -dessication (cannot be used for sterilization) -high pressure (cannot be used for sterilization) -osmotic pressure (not reliable for sterilization) -radiation (can be used for sterilization) -filtration (can be used for sterilization)
What is an inactivated killed vaccine, a live attenuated vaccine and a subunit vaccine?
-inactivated killed virus: KILL or INACTIVATE the organism with heat or chemicals or radiation -live attenuated: Keep the microbe ALIVE but significantly REDUCE its VIRULENCE so that the microbe causes little to no disease -subunit: Purify a specific protein(s) from the microbe by biochemical methods (i.e., NOT the whole microbe but a part of it)
What are the three key molecules required for translation and what are the five basic steps that occur during translation?
-mRNA, tRNA, and ribosomes are required 1. initiation 2. elongation 3. termination 4. protein cleavage/ protein folding 5. chemical modifications
With respect to osmotic pressure, what type of environment will most bacteria encounter and what happens under this condition? What normally occurs when a bacterium is exposed to a hypertonic environment?
-most are isotonic -hypertonic: water moves out; plasmolysis -hypotonic: water moves in; lysis
What are the two types of natural immunity and explain how each can be acquired
-natural active: getting sick and getting better -natural passive: from mom before and after birth
Define and explain how each of the following handles the presence of oxygen: an obligate aerobe, a facultative anaerobe, an obligate anaerobe and an aerotolerant anaerobe. What is a microaerophilic microorganism and a capnophilic microorganism?
-obligate aerobe: has to have oxygen to survive -facultative anaerobe: can grow in the PRESENCE OR ABSENCE of O2 (but prefers O2 since more energy produced) -obligate anaerobe: can ONLY grow in the ABSENCE of O2 -aerotolerant anaerobe: can ONLY grow in the ABSENCE of O2 but will tolerate and not be killed by the presence of O2 -microaerophilic: can ONLY survive and grow under lower O2 concentrations (typically 1-10% O2) -canophilic: Some microbes require less O2 but MORE CO2
Define and explain the nutritional patterns of the following: a photoautotroph, a photoheterotroph, a chemoautotroph, a chemoheterotroph, a saprophyte and a parasite.
-photoautotroph: light & inorganic material -photoheterotroph: light & organic material from others -chemoautotroph: chemical bond breaking & inorganic material -chemoheterotroph: chemical bond breaking & organic material from others -saprophyte: nutrients from DEAD or decaying organic matter -parasite: nutrients from a LIVING (organic) host
What are the general characteristics of algae?
-photosynthetic organisms that contain chloroplasts & chlorophyll and can reproduce asexually and sexually -mostly inhabit aquatic environments -can vary from simple unicellular organisms to complex multicellular organisms -rarely cause direct disease in human; however, the toxins some algae secrete into the environment can be deadly
List 3 groups of antifungal drugs, indicate what each group of drug specifically targets and describe the mode of action for each group of drugs
-polyenes: Binds to ergosterol in cell membranes & creates PORES so cell contents leak out -azoles: INHIBITS metabolic pathway so correct form of ergosterol is NOT synthesized -Echinocandins: INTERFERS with the enzyme that attaches the β-glucans to the cell wall= β-glucans NOT linked to the fungal CELL WALL so cell more susceptible to LYSIS -All target ERGOSTEROLS β-GLUCANS
Define the following: psychrophiles, psychrotrophs, mesophiles, thermophiles and hyperthermophiles.
-psychrophiles: CANNOT grow above room temperature (>20°C) -psychrotrophs: CANNOT grow above 30°C but can grow at temperatures between 4°C (refrigerator temperature) and room temperature= FOOD SPOILAGE MICROBES -mesophiles: moderate/middle temperature-loving microbes 25-40 C) -thermophiles: optimal growth temperature between 50-70°C most CANNOT live at temperatures below 40°C -hyperthermophiles: HYPERTHERMOPHILES have an optimal growth temperature ≥ 80°C
Draw a graph to illustrate what happens to a person's antibody titer when they are infected with a microbe they have never encountered before or are vaccinated for the first time. What is this response called? On the same graph draw what happens to a person's antibody titer after they recover from the initial illness but encounter the disease-causing microbe again or are given a booster vaccine. What is this response called?
-small hump then larger one -very start: seeing the pathogen for the first time -primary recovery: first peak -dip: seeing the pathogen again/vaccine booster -large hump: secondary response -obtaining natural active immunity/ artificial active immunity (vaccine)
What are the 2 antibacterial drug groups that target folic acid metabolism, what enzymes do these drugs specifically target and describe each drug's mode of action
-sulfonamides: (Pteridine synthetase) competitive inhibition with PABA substrate -trimethoprim: (Dihydrofolate reductase) competitive inhibition with dihydrafolic acid
Explain why fever is considered a defense mechanism against infection
-temperature-sensitive pathogens will NOT grow -high body temperatures increases replication of immune cells, enhances phagocytosis, decreases amount of iron available to microbes and speeds up tissue repair
What are the general characteristics of protozoa? Specifically how do these organisms reproduce (asexually, sexually or both?), take in nutrients and move?
-very large group of unicellular microorganism (~20,000 species) -typically most are non-pathogenic and inhabit moist environments like soil & water; however, a few can infect humans and animals with potentially devastating results -can produce asexually (binary fission, budding, schizgony) -some can reproduce sexually (conjugation or gametosis) -acquisition of nutrients can occur by: absorption across the plasma membrane, phagocytosis (used by amoeba), specialized feeding structures (e.g., oral groove or cytostome) -locomotion can occur through: Flagella, Cilia, Extension of the cell membrane like pseudopodia or undulating membranes
What does a viral genome consist of? What is a viral capsid, viral spikes and a viral envelope? What are the three basic viral shapes?
-viral genome: all the genetic information of an organism -capsid: all viruses have a protein shell called a CAPSID; the capsid surrounds and protects the genetic material of the virus -viral spikes: made up of glycoproteins project from the capsid and are used to promote viral attachment to host cells -viral envelope: envelope composed of lipid bilayer with carbohydrates and proteins, including viral spikes; the envelope is actually from the membrane of the eukaryotic cell the virus infected and destroyed; envelope further serves to protect genetic material Shapes: helical, icosahedron, ENVELOPED HELICAL OR ICOSAHEDRON VIRUSES
What are the 2 microscopic types of fungus and how do these organisms differ in terms of their morphology and methods of reproduction?
-yeast are unicellular and are typically round/oval and reproduce by budding (asexual) -molds are multicellular hyphae (long filaments that are joined together) and reproduce by hyphae above the surface of the medium that carry reproductive spores
List three types of vaccines that are the result of genetic engineering and briefly explain/describe how each of these works
1. recombinant subunit vaccines (administration of protein from gene) 2. DNA vaccines (administration of plasmid from gene) 3. virus-like particles (capsid of the virus)
What are the three major mechanisms by which antiviral drugs can inhibit/stop an infection?
1. Blocking virus entry into the cell 2. Blocking transcription & translation of viral molecules 3. Preventing assembly of infectious viral particles
List the seven phases/stages that occur during phagocytosis
1. Chemotaxis 2. Adherence 3. Ingestion 4. Formation of a Phagosome 5. Formation of a Phagolysosome 6. Digestion 7. Discharge
What are the 5 basic steps in the manufacturing of a bacterial-based product and list three non-food/beverage products that microorganisms have been used to produce
1. Introduction of raw materials (e.g. the media components and the bacteria) 2. Growth of the bacterial culture in the bioreactor/fermentation tank 3. Downstream processing (e.g. all the further biochemical procedures required to purify the product from waste compounds) 4. Mixing (formulation) and filling of final product 5. Labeling and packaging of the final product -vaccines, antibiotics, vitamins, steriods
What three important properties should an ideal antimicrobial drug possess and why?
1. Selective toxicity (toxic to the microbe but nontoxic to the host) 2. Bactericidal RATHER THAN bacteriostatic 3. Does NOT lead to development of antimicrobial resistance
Explain the steps required for transcription to occur. Specifically, which strand of DNA is transcribed (template or coding strand), where transcription starts and ends, what enzyme is required for transcription and what the final product of transcription is?
1. The transcription machinery, which includes the enzyme RNA POLYMERASE binds to the promoter region on the DNA strand 2. RNA POLYMERASE unwinds the DNA helix and separates the DNA strands 3. RNA POLYMERASE moves down the template strand in a 5' to 3' direction incorporating nucleotides complimentary to the DNA strand 4. RNA POLYMERASE continues to move down the template strand in a 5' to 3' direction incorporating nucleotides complimentary to the DNA strand; RNA POLYMERASE continues down the template until it encounters the terminator sequence, which causes the polymerase to release from the template -the template strand is transcribed -begins at the promoter region and ends at terminator sequence -final produce of transcription is mRNA
List 5 antibacterial drug groups that target the bacterial protein synthesis and for each indicate what ribosomal subunit the drug specifically targets and describe the drug's mode of action
1. aminoglycosides: binds to the 30S ribosomal subunit and causes its shape to change which IMPAIRS the ribosome's PROOFREADING ABILITY so codon/anticodon MISMATCHES occur= codon/anticodon MISMATCHES means wrong tRNA used and therefore WRONG AMINO ACID incorporated in protein leading to missense or nonsense MUTATIONS 2. tetracyclines: binds to the 30S ribosomal subunit, which blocks tRNAs from entering and binding within the A SITE of the ribosome= tRNA CANNOT ENTER and BIND within the A site of the ribosome= growing polypeptide chain CANNOT undergo elongation= translation of protein STOPS 3. Chloramphenicol: binds to the 50S ribosomal subunit, which PREVENTS peptide bond FORMATION between the amino acids associated with the tRNAs in the A and P sites of the ribosome= inability to form peptide bonds between amino acids associated with tRNAs in A and P sites BLOCKS ELONGATION of polypeptide chain= translation stops 4. macrolides: binds to the 50S ribosomal subunit, which PREVENTS translocation of the tRNAs between the P, A and E sites of the ribosome= inability to undergo translocation BLOCKS ELONGATION of the polypeptide chain= translation stops 5. Oxazolidinones: binds to the 50S ribosomal subunit, which PREVENTS the ribosomal subunits from JOINING= no joining of ribosomal subunits = NO functional 70S RIBOSOME produced= NO translation can occur
List the five primary targets that antibacterial agents can act on
1. cell wall 2. ribosomes 3. nucleic acid synthesis 4. metabolic pathways 5. plasma membrane
What are the five specific mechanisms that can lead to antimicrobial resistance?
1. inactivation of drug by enzymes 2. blocking drug entry 3. increased drug elimination 4. altering drug targets 5. metabolic pathway ByPASS/SWITCHING
List 5 antibacterial drug groups that target the bacterial cell wall and for each indicate what the drug targets and describe the drug's mode of action
1. penicillin: Penicillins block TRANSpeptidase activity so NO peptide cross-linked bridges= weak cell wall= lysis 2. cephalosporin: Cephalosporins block TRANSpeptidase activity so NO peptide cross-linked bridges= weak cell wall= lysis 3. vancomycin: BLOCKS attachment of the 4 amino acid tetrapeptide side chain to NAM sugars= weak cell wall= lysis 4. bacitracin: interferes with the transport of peptidoglycan components across the inner plasma membrane in both Gram negative and Gram positive bacteria= no peptidoglycan in cell wall= weak cell wall= lysis 5. Isoniazid: BLOCKS the synthesis of mycolic acid= NO mycolic acid layer in the cell wall= weak cell wall= lysis
List the two general means by which resistance to antimicrobial drugs can arise
1. spontaneous gene mutation: spontaneous events that occur RANDOMLY and at a LOW FREQUENCY 2. Acquisition of a new gene or genes from another bacterial species: transfer of resistance factors on PLASMIDS; acquisition can occur via CONJUGATION, TRANSFORMATION or TRANSDUCTION
What are the steps involved in the infectious cycle of an animal virus? What are the two ways a virus can enter an animal cell and what are the two ways a virus can be released from an animal cell?
Animal virus: attachment, entry/penetration, uncoating, biosynthesis, assembly, release Entry: receptor mediated endocytosis and membrane fusion Release: cell lysis or budding
Define the terms broad host range, restricted host range and tissue tropism
Broad: virus can infect many different species because of a common receptor shared by many different species Restricted: virus can only infect 1 specific species because receptor is unique to 1 species Tissue tropism: a virus that infects 1 specific tissue or cell type because receptor is unique to 1 type of tissue/cell
What are the 2 key chemical processes in the carbon cycle associated with microorganisms and what are the 4 key steps in the nitrogen cycle associated with microorganisms?
Carbon cycle: Microbes like FUNGI and BACTERIA in the soil or MARINE MICROBES eat organic material & Microbes like ALGAE and BACTERIA (e.g., Cyanobacteria) absorb CO2 Nitrogen cycle: Nitrogen Fixation: N2 --> NH3 Nitrification: NH4 --> NO3 Denitrification: NO3 (nitrite) --> N2 Ammonification: proteins of decayed organisms -->NH3
List five factors that can influence the rate at which a bactericidal chemical compound such as a disinfectant can kill a bacterium and the three key bacterial components/structures that a bactericidal chemical compound can target
Factors: time, agent concentration, # of microbes, type of bacteria present, environmental factors (blood, fecal matter, biofilm) Targets: membranes, nucleic acids, proteins
How many lines of defense do we have against invading pathogens? Which lines of defense are associated with innate immunity and which are associated with acquired/adaptive immunity?
Innate (first and second line defense); adaptive (third line of defense)
What specific characteristics do mitochondria and chloroplasts possess that supports the theory of endosymbiosis?
Mitochondria and chloroplasts used to be their own bacteria that were ingested by cells and became organelles because they could no longer survive on their own
Name the 7 different groups of microorganisms. Which of the three domains of life does each group fit into? Which are prokaryotes and which are eukaryotes? What is a virus?
Prokaryotes: bacteria, archaea Eukaryotes: algae, fungi, protozoa, helminths Viruses are NEITHER eukaryotic or prokaryotic cells instead they are considered as ACELLULAR (not consisting of cells) and are therefore termed, PARTICLES
Explain the steps required for DNA replication in bacteria. Specifically, where does replication start on the bacterial chromosome and what are the enzymes necessary for DNA replication of the leading and lagging strands?
Replication: 1. RELAX the supercoiled circular DNA chromosome (TOPOISOMERASE & DNA GYRASE) 2. Unwind and separate the two DNA strands by breaking the hydrogen bonds between the base pairs (helicase) (begins at the origin of replication=replication fork) 3. Short SINGLE-STRANDED BINDING PROTEINS (SSBP) bind to the unwound/separated DNA strands so they do not immediately rejoin 4. Generate short RNA PRIMERS on each strand of DNA (RNA primase) 5. Binding of DNA POLYMERASE III to each strand of DNA 6. DNA POLYMERASE III begins to proceed down the strand of parental DNA synthesizing a new strand of DNA by adding complementary nucleotides 7. RNA primase attaches to the lagging strand and makes a short RNA primer that has a free 3' end 8. DNA POLYMERASE III will use the free 3'-OH end of the RNA primer to begin to synthesize DNA from the lagging strand but Every time the DNA POLYMERASE III runs into an old RNA primer it stops and re-starts at a new RNA primer (DISCONTINUOUS SYNTHESIS) 9. Digest the RNA primers on each Okazaki fragment and replace it with DNA using DNA POLYMERASE I 10. DNA LIGASE is used to repair the gaps and join the fragments of the lagging strand
What is a toxoid and what can it be used as?
Toxoid = a toxin that has been inactivated by chemical treatment or by introducing mutations by genetic engineering -can be used to make an antitoxin
What is an anti-toxin? When would an anti-toxin be used/administered to a person?
antibodies that are produced in another host/animal, purified and then administered to a patient who ALREADY has the disease (artificial passive immunity)
List 5 reasons why infectious diseases are still a rising peril
association with cancer, anti-vaccine movement, bioterrism, antibiotic resistance, global travel
Explain the difference between a bactericidal compound and a bacteriostatic compound?
bacteriostatic a chemical that prevents bacterial growth but does not kill the organism while bactericidal is a chemical that destroys/kills bacteria but not necessarily endospores
How do most bacteria reproduce?
binary fission
What cells are involved in cellular immunity and what type of pathogens are cell-mediated responses directed against?
cell-mediated immunity= T cells; intracellular pathogens
What are the three types of chemical bonds and in simple terms how is each formed?
covalent (strongest)- sharing electrons Ionic- gain or loss of electrons Hydrogen (weakest)- hydrogen is attracted to a nitrogen or oxygen atom
Explain how the first eukaryotic cell arose from a primitive prokaryotic cell and what is the name of this theory?
endosymbiotic theory- 1. infoldings of the plasma membrane generates nucleus and other organelles 2. consumption of an aerobic bacterium that survives within the larger cell --> evolves to become mitochondrion 3. meal #2, consumption of a photosynthetic bacterium that survives within the larger cell --> evolves to become chloroplast
Who is more resistant to drying and who is more resistant to antibiotics, a Gram positive bacterium or a Gram negative bacterium and why?
gram negative are more resistant because they have 2 plasma membranes to protect the cell
What are the five signs of inflammation?
heat, redness, swelling, pain, loss of function
What cells are involved in humoral immunity and what type of pathogens is the humoral response directed against?
humoral immunity= B cells; EXTRACELLULAR pathogens
What two types of immunity can host defenses be divided into and describe the specificity of each
innate (non-specific) and adaptive (specific)
What are the common properties/features of inorganic and organic compounds?
inorganic-small & simple in structure; predominantly held together by ionic bonds; typically lack carbon (exception CO2); examples include: water, salts, acids and bases organic- complex in size & structure; predominantly held together by covalent bonds; ALWAYS contain carbon and hydrogen; consist of the four macromolecules of life
Name three types of leukocytes that can be classified as phagocytes and act as the second line of defense against microbial pathogens
monocytes, neutrophils, dendritic cells
What are growth factors?
organic compounds that must be provided to a microbe as a nutrient
List any 5 front/first line defenses human possess against microbial pathogens
skin, mucous membranes, tears, nasal hairs, sebum
Bioaugmentation
the addition of genetically modified microorganisms to the site of contamination to aide the clean-up process
Bioremediation
the use of microbes to remove pollutants from a contaminated site
What is so different about the cell wall of Mycobacterium species?
their cell wall is made of mycolic acid which makes the bacteria more resistant to disinfectants and drying
