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Microbiology Midterm Exam 2025 Latest Questions &
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Define Micro- Less than 1mm and cannot see with the naked eye Need a microscope to see Microbes, microorganisms, germs, bugs What are the 5 groups of microorganisms studied? Bacteria--most famous Virus--2nd Fungus--3rd Protozoa--some but few Algae--not a human pathogen What generates 1/2 of the O2 that we breathe and would make life impossible without? Microbes What is the smallest simplest single-celled organism? Bacteria What is not a cell, can't live by itself and needs to invade a cell? Virus What are the two different classification of fungus? Molds and yeast--micro Mushrooms--Macro What is a mostly single-celled organism that is Animal like? Protozoa What are parasites? Different organisms that range from worms, insects and protozoa that need a host to survive What are the different applied microbiology fields of study
Immunology Epidemiology--control spread of disease Food Micro--relationship between bacteria, food and drink Agriculture Micro--relationship between bacteria and crop Industrial Micro--microbes to produce vitamins, AA, Enzymes, etc. Eukaryotic cells are... more complete Prokaryotic cells are... all micro organisms and lack a nucleus Characteristics of microorganisms Small size Unicellular simplicity High Growth rate Adaptability microscope instrument used for enlargement of small objects simple microscope single lens and a few working parts. not strong compound microscope 2 magnifying lenses, a visible light sours, a condenser which collects light to direct toward the object magnification capacity of an optical system to enlarge small objects ocular lens one we look through. 10X objective lens 4 different, 4X, 10X, 40X, 100X What is resoltion?
made of protein with 3 distinct parts: filament, hook, basal body (inside and has 4 rings and a rod that rotate) axial filament wrap around the cell and cause spiral like movements. has only two parts: a long thin microfibril inserted into a hook. attachment appendages fimbriae and pili fimbriae short appendages that allow bacteria to attach to bacteria pili long appendages are found in gram negative bacteria and are useful when mating cell envelope the bacterial surface (glycocalyx), the cell wall, cell membrane glycocalyx/bacterial surface this layer is a coating to protect the cell. two types slime layer type of glycocalyx that protects bacteria from loss of water and nutrients and loosely bound to the bacteria capsule thick, gummy consistency. It is tightly bound to the bacteria and is not easily washed off cell wall the layer beneath the glycocalyx and provides the cell with structure. It determines the shape of the bacterium from bursting or collapsing from changes in pressure. ESSENTIAL for bacterial survival peptidogylcan provides the protective quality of the cell wall. rigid. compose of long glycol chains. forms a meshwork. gram positive cell wall
purple. thick sheet with peptidoglycan and tightly bound polysaccharides. has a lot of peptidoglycan which binds to the purple die gram negative cell wall pink. small amounts of peptidoglycan and there is a large space between the peptidoglycan and the outer membrane Gram Staining
- crystal violet (both will turn purple. gram + will have more precipitin on cell wall bc more peptidoglycan)
- grams iodine (not a stain. binding agent)
- alcohol (washes color off gram -. too much is bound to gram + to wash off)
- safranin (red/pink, gram negative will take up this stain) Why doesn't the outer membrane associated with gram negative bacteria prevent the alcohol from washing off the crystal violet? The outer layer is made of lipids, not glycoproteins. Alcohol can dissolve the lipids and wash the stain off of the peptidoglycan underneath cell membrane thin, flexible, has phospholipids and proteins. functions to extract energy, process nutrients. important site of metabolic activities and structural molecule synthesis protoplasm internal contents of the cell: dense, gelatinous cell pool in protoplasm, composed of water, sugar, amino acids, salts. Contains: chromatin body, plasmids, ribosomes, mesosomes, granules (membrane bound {organic compounds} and non membrane bound {store inorganic compounds}) Bacterial nucleus not surrounded by membrane, does not have mitotic apparatus, observable in stained cells Bacterial cytoplasm contains ribosomes, granules, no organelles Bacterial ribosomes
population growth the basis of population growth is from binary fission generation time/doubling time time required for a complete fusion cycle from parent cell to 2 daughter cells generation doubling process when the population increases by a factor of two Pattern of bacterial growth
- Lag Phase: cells increasing in size (5hrs)
- Exponential growth phase: depends on proper growth conditions, curve increases, this phase continues as long as cells have adequate nutrients. dividing rapidly (5-16 hrs)
- stationary phase: decline in growth rate, increase in death rate. less optimal conditions. numbers remain equal (16-33 hrs)
- death phase: rapid death depending on resistance of species, nutrients deplete (33-45 hrs) Ways to measure bacterial growth spectrophotometer, viable colony count spectrophotometer way to measure bacterial growth. a machine that measures approximate color and cloudiness of water so we can estimate the number of bacteria in it viable colony count more detailed. involves making a serial dilution of the solution and you get the exact number of bacteria Bacterial metabolism cellular chemical changes resulting from all chemical reactions and the physical working of the cell. anabolism, catabolism anabolism
synthesis of cells, molecules, or structures catabolism degrative reaction. breaking down large molecules into smaller molecules and producing energy enzyme facilitate reactions by lowering the energy of activation a) most cellular runs are catalyzed by enzymes b) enzymes are proteins that act specifically c)enzymes speed the rate of metabolic activity genetics study of the inheritance or heredity of living things genetic material long, encoded molecule of DNA with several orders of structure genome total of genetic materials in cell. varies from 4-5 genes to >100,000 genes chromosome cellular structure composed of a long neatly packaged piece of DNA gene organismic: unit of heredity responsible for a given trait cellular: site on chromosome that provides info for a certain cell function molecular: certain DNA segment that contains the necessary code to make a protein or RNA molecule DNA structure nucleic acid with 2 polynucleotide strands combined into a double helix. deoxyribose sugar phosphate attached to a nitrogenous base Nucleotide 3 parts:
- one of 5 possible nitrogenous bases. PURINES: Adenine, Guanine PYRIMIDINES: Cytosine, Uracil, Thiamine (C-->G, A-->T)
- RNA's sugar (ribose) is more readily destroyed than DNA's sugar (deoxyribose) so that the body can destroy it when its purpose is served.
- Adenine-->Uracil, Cytosine-->Guanine
- DNA is double stranded, RNA is single stranded Types of RNA messenger RNA, ribosomal RNA, transfer RNA transcription information is transcribed from DNA to mRNA. mRNA carries the info to ribosomes. rRNA is in the ribosome.
- DNA is unzipped by RNA polymerase
- nitrogenous bases arrange a complimentary strand to one of the DNA strands
- single stranded mRNA leaves the DNA and travels to the ribosome translation tRNA translates the info from nucleic acid language (AU, CG) to amino acid language. tRNA reads codes of info off the mRNA and also builds the chains of proteins out of amino acids
- rRNA brings amino acids to the part of the ribosomes where proteins are made
- AA's are stacked into a chain by tRNA based on mRNA
- protein is formed, folded, released Gene regulation in bacteria controlled by the operon! OPERON: cluster of genes can control catabolism and anabolism Lactose operon (catabolism) ~controls catabolism of lactose
- Regulator: has one gene. functions to make a protein that will repress the function of the operon
- Control Locus (Promotor: GCTAGC, Operator:where transcription is initiated)
- Structural Locus: 3 genes that code for enzymes needed to catabolize lactose FUNCTION: normally in the OFF mode and does not initiate the enzyme synthesis when lactose (the substrate) is not present. When lactose is present, the operon begins to function. The regulator makes repressor protein which represses the operon by blocking transcription by binding to the
operator gene. Lactose binds to the repressor protein and removes it from the operator gene! SO, the operon begins functioning and transcription begins of the 3 proteins/enzymes that break down lactose. Without lactose bound to the repressor protein, it is free and can bind again so no more enzymes will be made Repressible operon Controls anabolism! The repressible operon is the bacterial system for amino acid, purine, and pyrimidine synthesis. Normally in the ON mode and will be turned off when only this nutrient is no longer needed STRUCTURE: structure is the same as the lactose operon. the repressible operon is on and the repressor protein is inactive. operator gene controls transcription for 3 genes which instruct proteins to be made--constantly being made. (i.e. proteins are needed to make arginine) What happens when there isn't enough arginine? The arginine will then bind to the repressor protein making the repressor protein active. It will sit on the operator gene blocking transcription (no enzyme production and blocks arginine from being made). When arginine is used up, the one bound to the repressor protein will break free making the repressor protein inactive. Where does the repressor protein bind? operator gene How does the lactose operon turn on? presence of lactose How does the repressor operon turn off? presence of too much arginine What is a mutation?
- a permanent inheritable change in the genetic information of cell is a mutation
- an alteration in the nitrogen base sequence of DNA (wild type strain and mutant strain) Spontaneous mutation
aka bacterial sex 2 related species (donor/recipient) transfer a plasmid through a pilus
- transduction bacterial transfer mediated through a bacterial virus. a bacteriopahge is a virus that can infect a bacteria. It takes a gene from one bacteria and carries it to the other bacterial cell. the bacteria are NOT attached. Onve virus takes a piece of the bacterial dan and it bursts and the viruses infect other bacteria and incorporates itself into the new bacteria's DNA. (viruses have 2 stages: lytic (reproduce/rupture) and latent (virus invades and incorporates itself into the DNA))
- transformation the gene from a virus or dead bacteria can go into live bacteria making it more virulent. this is the basis of cloning. transfer of naked DNA that requires no special vehicle transposition jumping gene! Transposons can not replicate, they move from one bacteria to another. can travel from a chromosome to a plasmid or from a plasmid to a chromosome Temperature effects on microbes Minimum temperature: lowest temperature that permits a microbes continued growth/metabolism Maximum temperature: highest temperature at which growth and metabolism can proceed (--
stop, -->dead) Optimum temperature: small range pschrophile microbes grow best below 15C and 0C mesophile microbes that grow at 20-40C (HUMAN PATHOGEN) thermoduric microbes that can survive short exposure to high temperatures which are normally mesophiles (i.e. spore forming or thick walled) thermophile microbe that grows optimally above 45C GAS effects on microbial growth
Oxygen, carbon dioxide, nitrogen aerobic microorganism grow well in the presence of normal atmospheric oxygen and possess enzymes to process toxic oxygen product facultative anaerobes can survive without oxygen. possesses catalase and dismutase enzymes microaerophyle does not grow at normal atmospheric tensions, but requires some oxygen to metabolize anaerobe do not grow in normal atmospheric oxygen, lacks metabolic enzyme to use oxygen Microbial interactions interrelationships occur between microbes, may involve multicellular organisms, can be beneficial, neutral, harmful synergism cooperative relationship between organisms that is beneficial to both, but not obligatory commensalism one member is not harmed or benefited while it provides benefits to the other member parasitism harmful interrelationship (pathogenic bacteria in our body) antagonism parasitism when members of a community compete. disease condition where there is incorrect functioning due to the effect of heredity, infection, diet, environment. malfunction of a tissue/organ infection
natural substance. produced by a microorganism that is harmful to another microorganism synthetic drugs made in a lab using various compounds interaction of drug cell microorganisms absorptive, delivery, drug function, breading down of drug by host organ microbiocidal destructive to microbes microbiostatic inhibits the growth or multiplication of micro biota mechanism of action of antimicrobial agents
- cell wall synthesis inhibited (affects new cells w lil baby cell walls)
- cell membrane function is prevented
- protein synthesis inhibited
- nucleic acid synthesis inhibited (remains potent, no allergies, microbiocidal vs microbiostatic, inhibition of biochemical events for parasite, but not the host) Inhibition of cell wall synthesis animal cell: no cell wall bacterial cell: cell wall prevents against hypotonicenvironment and gives shape Characteristics of cell wall
- rigid
- has peptidoglycan a. gram negative bacteria: has less, so cell wall is less rigid b. gram positive bacteria: has more, so cell wall is more rigid B-lactan drugs (penicillin and cephalosporin) these drugs can block enzymes required to build peptidoglycan and prevent the synthesis of the cell wall in gram + bacteria. they don't work in gram - bacteria which are equipped with additional coating in the cell wall, in addition to peptidoglycan bacteriocidal
kill bacteria. penicillin is effective against new baby bacterial cells but no effect on older/dormant bacterial cells. When it inhibits cell wall synthesis in young cells, the following happens: damaged membrane, metabolic insufficiency, lysis and cell death polymysin effective against gram - bacteria. Antibacterial. polyenes, imidazoles antifungal microbiocidals are _____ to humans OMG SO TOXIC Inhibition of protein synthesis can be selectively toxic to bacterial ribosomes, not in human ribosomes (they are too big). No protein=no enzyme=bacterial death drugs that block protein synthesis
- aminoglycosides
- tetracycline
- chloramphenical
- erythromycin Inhibition of nucleic acid block specific enzymes which bacteria need in order to replicate their DNA and RNA Inhibition of transcription or nucleic acid synthesis models of competitive inhibition. (examples include the sulfa drug, sulfonamide and rifampin). E.g. Sulfa is very similar to the natural metabolic compound, PABA (para aminobenzoic acid) which is needed by bacteria to make folic acid to make nucleic acid. Sulfa blocks papa from binding to the enzyme Microorganisms can acquire resistance to antibiotics
- microbes have the ability to destroy the antibiotic
- microbes have the ability to make changes in the permeability of their cell wall and membrane
- resistance to the drug may develop from production of penicillinase to resist penicillin OR
acyclovoir (herpes), AZT (Aids), Interferon (naturally produced by fibroblasts and leukocytes in an infected cell. We can use cells to create interferons in the lab, trying to speed up the process that the body uses to fight the virus) side effects of antimicrobial drugs tissue damage, allergic reaction, disruption in the balance (i.e. yeast infection) transient microorganisms that are rapidly lost infectious microorganisms that invade tissue and lead to infection contaminant presence of infectious agent in the tissue without yet INVADING it. morbidity damaged tissues and organs may lead to dysfunction mortality damage may be enough to cause death flora of the mouth most diverse and abundant of the body since it provides hundreds of niches for them to colonize and grow. The environment is good for bacterial growth. for example: a)aerobic streptococci: cheek, tongue, floor of mouth, tooth b)streptococcus mutans/sanguis: major contributors to dental cavities--ew Infection process 1)microbes enter the body
- cross the host barrier--the immune system
- multiply in the target tissue and produce toxins and enzymes causing infection
- released to exterior--get out of the body and start in another individual The portal of entry and initiation of infection skin/membranous boundaries are route for entry. Each microorganism has one or two specific portals entry specific.
Site of inoculation: infectious dose is the minimum amount of organisms required to initiate infection pathogenicity the capacity of a microorganism to cause infection or disease. Pathogenic microbes are capable of causing infections and disease in healthy people! Normal flora microbes are opportunistic that infect people with compromised immune systems Invasion of tissue damage, infection continued!
- adhesion occurs: bacteria- pilli, fimbria, capsule, slime layer virus- specialized receptor protozoa- organelle of locomotion parasitic worms- suckers, hooks
- virulence: exoenzymes dissolve host defense barrier and promote the spread of microbes to deeper tissues (exoenzymes i.e. mucinase, keratinase, collagenase, hyaluronidase, coagulase, bacterial kinase) stages of infection and disease
- incubation: infected. no symptoms
- prodromal: microbes multiply, signs and symptoms occur
- period of invasion: microbes growing and maximal signs and symptoms
- convalescent period: body recovers as bacteria number decrease
- termianl stage: we die! If convalescent period doesn't happen Pattern of infection 1: localized infection, bacteria limited to one place 2: generalize/systemic infection: bateri gets into fluid and spreads 3: focal infection: infection spreads from one area to another 4: mixed: infection by more than one type of microbe 5: acute infection: severe, infection period short 6: chronic infection: severity is low, timing is long 7: subacute: midway between acute and chronic Warning signals of disease signs, symptoms, syndromes, blood signs (leukocytosis- inc in WBC, leukopenia- dec in WBC, septicemia-microbe multiplication in blood, bacteremia, viremia
