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Mod 6 - Microbiology
| Question | Answer |
|---|---|
| Microbiology | The study of microorganisms (microbes): - Viruses - Bacteria - Parasites - Fungi - Others |
| Prokaryotes vs Eukaryotes | PROKARYOTES DO NOT HAVE: - membrane bound nucleus - membrane bound organelles - DNA that is organized into chromosomes. |
| Prokaryotes Classification | - All living cells are either prokaryotes or eukayotes - All bacteria are prokaryotic cells - Divided into (5) classes - Prokaryons in Kingdom Monera - Many classes - Earth's most abundant form - 0.5-2UM in size |
| Prokaryotic Cell Structures | - Cytoplasm - Ribosomes - Nucleoid (chromosome) - Inclusion Bodies - Some prokaryotes secrete a capsule & have plasmids. |
| Prokaryotic Cytoplasm | - Semi-fluid substance that fills inner cellular space - Primarily water with carbohydrates, lipids, and various enzymes. |
| Prokaryotic Ribosomes | - Consists of RNA and protein - Used in protein synthesis |
| Prokaryotic Nucleoid | - Chromosomes - No real nucleus |
| Prokaryote Inclusion Bodies | Stores molecules essential to cell function. |
| Capsule | A protective structure that serves as a defense mechanism in some prokaryotes consisting of: - Tightly bound wall with complex polysaccharide molecules that form a gel-like covering that surrounds the bacterial cell. |
| Plasmids | Some prokayrotes contain a self-replicating extrachromosomal DNA that carry 1 or more pieces of genetic information, not required to sustain life. |
| Prokaryote Cell Structure | Cell Wall: - Shape & stability - Contain peptidoglycan, large polymer resembling a "chain link fence" - Antibiotics target cell wall (i.e penicillin) "Eukaryotes do not have cell wall" |
| Prokaryote Cell Membrane (aka plasma membrane) | - Regulates transport of material in and out of the cell - Made of phospholipids - Long-chain fatty acids and proteins - Selectively permeable |
| Peptiglycan | Large polymer which makes up a prokaryote cell membrane with an immense, covalently-linked molecule linked in multi-layers resembling a "chain-link" fence |
| Flagellum (singular); Flagella (plural) | Filamentous organelles of locomotion found on half all known bacteria |
| Motile | Various degrees of movement |
| Pili (singular: pilus) | Tiny, tube-like projections from the cell's surface associated with adherence |
| Prokaryotic Bacterial Cells: (Shape & Arrangement) | - characterized by shape & size - before culture information is available, location and appearance characteristics were used |
| Cocci (singular: coccus) | Spherical bacterial cells |
| Bacilli (singular: bacillus) | Rod-shaped bacterial cell resembling a hot dog |
| Vibrios | Comma shaped bacterial cell |
| Coccobacillus | Bacterial cell shaped between cocci & bacilli |
| Spirillia | Bacterial cell which appears loosely-coiled or wavy |
| Spirochetes | Bacterial cell which appear tightly coiled, corkscrew-shaped rods. |
| Gram Stain | Method used to group bacteria into 2 different catagories: - Gram positive bacteria (purple) - Gram negative bacteria (pink) |
| Gram-Positive Bacteria | - Thick layer of peptidoglycan (thick cell wall) - Teichoic acid causes retention of crystal violet (blue) dye |
| Gram-Negative Bacteria | - Thin layer of peptidoglycan (thin cell wall) - High lipoprotein content which releases crystal violet dye when rinsed with alcohol - The safranin (pink) counterstain is retained |
| Gram Stain Method | 1-Sample smeared on slide & fixed with heat 2-Slide stained with crystal violet (purple)@ 1-2 mins. 3-Gram's iodine used to "fix" the crystal violet (help retain stain) 4-Acetone used to decolorize slide 5-Stain slide w/safranin (pink) |
| Diplococci | - Cocci in pairs - Ex.: Gonorrhea |
| Streptococci | - Cocci in chains - Ex.: Aureus, Boils |
| Staphylococci | - Cocci in grape like pairs - Ex.: Staphylo (irregular clusters) |
| Culture Media - Identifing Specific Bacteria | - Can be liquid or semi-solid - 3 Different Types: < Enriched Media < Selective Media < Differential Media |
| Tetrad | - Group of four - Micrococcus - Rarely pathogenic |
| Enriched Media | encourages the growth of most bacteria (Sheep's blood "Agar plate") |
| Selective Media | Encourages the growth of some bacteria which inhibiting others ("MacConkey" Agar) |
| Differential Media | Groups bacteria based on the fermentation of carbohydrates ("MacConkey" Agar) |
| MacConkey Agar | Used in both Selective and Differential Media |
| Aerobes | - Require atmospheric oxygen - Ex.: Staphylococcus, Streptococcus, E. coli |
| Anaerobes | - Require no oxygen - Ex.: Colstridium species, Gangrene - Used to put candle in the container until it burns out |
| Microaerophilis | - Require reduced oxygen & increased CO2 - Ex.: Campylobacter |
| Binary Fission | - Term used to describe cell division - Aka "Transverse Fission" - Do not have a cell cycle replicating their DNA - Continuosly dividing & |
| Lag Phase | - Gear up phase - Organisms not greatly increasing in #, but metabolically active < Growing, synthesizing enzymes, & producing lrg. amounts of ATP |
| Log Phase | - Once bacteria have adapted to nutrient-rich environment, growth is exponential (Logarithmic) - Generation time: genetically determined period of log. growth - Varies by species (min to hr) - Ex.: generation = 20 min < 1000 org/ml - initial < |
| Stationary Phase | - When the # of new cells produced is the same as the # of cells dying |
| Decline (Death) Phase | - # of cells dying is greater than the # of new cells arising from division |
| Symbiosis | - "Living together" in relation to bacteria - 3 Different types: < Mutualism < Parasitism < Commensalism |
| Mutualism | - Both the host & the microorganism benefit < E. coli, a bacterium that lives in the large intestines |
| Parasitism | - One organism benefits, the other is harmed < Tapeworm, Malaria |
| Commensalism | - One organism benefits, the other is neutral < skin bacteria, normal flora < majority of microbes |
| Normal Flora | - Organisms that live on or in the body but do not usually cause disease (commensals) < skin, conjunctiva, mouth, nose, throat, urinary tract, reproductive, & GI tracts. - Nutrients from oils & sweat facilitate colonization up to a dozen staph specie |
| Normal Flora in Infants | Infant have: - not acquired normal flora - less organic acid available to minimize growth - ideal environment to grow pathogens - Pathogens include: Grp B strep & Candida (yeast) |
| Resident Microflora | Organisms found on/in specific areas of the body |
| Transient Microflora | Organisms that "come and go" and exist in the same areas occupied by resident flora |
| Pathogenicity | Organism which benefits from its host and often lead to infection |
| Virulence | Term used to describe the intensity of bacterial & other microbial infections |
| Pathogenic Mechanisms of Bacteria | 3 Types: - Adherence - Colonization - Formation of a capsule |
| Adherence | Bacteria use pili to cling to surface of host cells, multiply & form colonies |
| Colonization | Once in place within host tissue, bacterial replication forms colonies and may overcome host defenses. < colonization in small #s of non-invasive organisms is normal in all animals |
| Formation of a Capsule | Capsule contributes to organism's virulence due to thick, polysaccharides structure - helps to resist host defense processes |
| Invasiveness | Ability of organisms to penetrate host tissue, usually by special enzyme |
| Enzymes contributing to Invasiveness | 3 Different Types: - Hyaluronidase - Coagulase - Streptokinase and Staphylokinase |
| Hyaluronidase | Attacks hyaluronic acid, the ground substance of connective tissue |
| Coagulase | Breaks down collagen, the framework of muscles |
| Streptokinase & Staphylokinase | Digest fibrin & prevent the clotting of blood < "flesh-eating bacteria" ex. of organism that produces streptokinase |
| Exotoxins | Secreted primarily by Gram-positive organisms < Gram (+) = botulism, gas gangrene, tetanus, staphylococcal food poisoning < Gram (-) = E. coli O157:H7 Shiga toxin |
| Endotoxins | - Release from Gram (-) bacteria when they die - Non-specific gastrointestinal symptoms such as diarrhea, cramping, & generalized malaise < Ex.: cholera, salmonella |
| Endospores | - Dormant form - Form when conditions are unfavorable for growth - Survive under harsh conditions < excessive heat or cold - Revert to active under favorable conditions - Clostridia species that cause tetanus, botulism, & gas gangrene form endosp |
| Exchange of Genetic Material | Bacteria can exchange genetic material 3 different ways: < Transformation < Transduction < Conjugation |
| Transformation | - DNA is acquired directly from the environment which was released from another cell through lysis etc. - Fragments are then "spliced" into the host cell's DNA |
| Transduction | - An asexual genetic process - Viruses (Bacteriophages or phages) transfer genes between mating bacteria |
| Conjugation | - Requires contact between 2 bacteria - utilizes a plasmid - transfers a greater amount of DNA than transformation or transduction - DNA is to be transferred from a donor cell to a recipient cell |
| F-Pilus | - Sex pilus - transfers DNA from one cell to another in conjugation |
| Plasmid | Extra-chromosomal DNA in the cytoplasm of some bacteria but not required by the bacterium |
| Resistance Transfer Factors | Bacteria which develop a drug resistance through plasmids |
| Genetic Recombination | By 3 different processes, transfers DNA leading to new strains of bacterium including antibiotic resistant strains |
| Antimicrobial Agents | Substances used to specifically treat infectious microbial diseases |
| Antibiotics | Antimicrobial agent containing substances derived from other organisms |
| Spectrum of Activity | Antimicrobial classifications: < Broad Spectrum < Narrow Spectrum |
| Broad Spectrum | Antimicrobials which are effective against a wide range of microorganisms including both gram (+) & gram (-) bacteria |
| Narrow Spectrum | Antibiotics are effective against a limited # of microorganism or single taxonomic group |
| Bacteriocidal Drug | Kills the organism |
| Bacteriostatic Drug | Inhibit the organism growth & allows immune defenses to act against the invader |
| Resistance Factors (Causes of) | Occurs through: - overuse of antibiotics - plasmids - genetic transfer mechanisms - development of neutralizing enzymes - alteration of pathways used by antibiotics - altering cell membrane permeability |
| Agar Disc Diffusion (Kirby Bauer Method) | - Uses paper discs impregnated with specific concentration of the antimicrobial to be tested - Result reported as either: < Sensitive: stays away from seed; inhibiting < Intermediate < Resistant: grows up to seed |
| Upper Respiratory Tract Infections | Pharyngitis - infections of upper tract: < pharynx < ears < eyes < sinuses < upper bronchioles - e.g. Strep throat caused by Streptococcus pyogenes |
| Lower Respirator Tract Infections | - Pneumonias - Casulated organisms that cause pneumonias include: < haemophilus influenza < Klebsiella pheumoniae < Streptococcus pneumoniae |
| Gastrointestinal Bacterial Infections | - Gastrointestinal - Contaminated food or water < Salmonella (raw eggs) < Shigella < Staphylococcus aureus < E. coli O157:H7 (raw hamburger, contaminated fecal material) |
| Nervous System Infections | - Meningitis < haemophilus influenzae (children) < Neisseria meningitidis < Vaccines available for both |
| Toxin-Induced Infections | - Botulism (Colstridium botulinum) - Tetanus (Colstridium tetani) - Toxic Shock Syndrome (Staphylococcus aureus) |
| Intracellular Bacteria | 2 Different Classes: - Chlamydia - Rickettsias - To a lesser extent: Mycoplasmas |
| Chlamydia Trachomatis | - intracellular organisms - require eukaryotic cell to replicate - causes variety of human infections including: < Trachoma (eye infection) < Sexually-transmitted disease causeing pelvic inflammatory dise. < Conjunctivitis in newborns |
| Richettsias | - Obligate intracellular parasite - Transmitted by a vector (ex. ticks & lice) - Rocky Mountain Spotted Fever (RMSF) - To human transmitted through the bite of the vector - Rocky Mountian spotted fever, Lyme Disease |
| Mycoplasma Pneumoniae | Primary atypical pneumonia "walking pneumonia" |
| Mycoplasmas | - Tiniest free-living organisms - Do not have a cell wall - Mycoplasma pneumoniae (walking pneumonia) < causes primary atypical pneumonia |
| Viruses | - Obligate Intracellular Parasite - Replicates w/n host cell - virus provides RNA or DNA to replicate - Host cell provides energy & resource - Contain RNA or DNA (not both) < RNA viruses contain code for reverse transcriptase, enzyme which makes D |
| Viral Structure | - Nucleic Acid (RNA or DNA) - Capsid: protective coat enveloping nucleic acid - Envelope < present in some viruses < May have glycoprotein spikes * determine specificity * hide virus from immune system |
| Nucleic Acid | Either a single or double strand of DNA or RNA, differing among viral groups |
| Capsids | - Enclosed within a protective coat - Determines the shape of the virus - Composed of individual protein subunits (capsomeres) - Can be helical, polyhedral (multi-sided) or bullet-shaped |
| Capsomeres | Individual protein subunits found in a capsid |
| Nucleocapsid | Combined capsid/nucleic acid arrangement |
| Viral Envelope | - External to the capsid - Acquired from combo of proteins, lipids & carbohydrates found in host cell |
| Spikes | A projection, usually glycoprotein molecules, that attach to specific sites on host cell wall |
| Viral Replication | Five Steps: - Adsorbtion - Penetration - Synthesis - Maturation - Release |
| Adsorption (Viral Replication - Step 1) | Attachment of virus to host cell < specificity to certain cells |
| Penetration (Viral Replication - Step 2) | Virus enters host cell (endocytosis or fusion) and "uncoats" (takes off envelope and capsid) |
| Synthesis (Viral Replication - Step 3) | Utilizes host nucleus to make new genetic material |
| Maturation (Viral Replication - Step 4) | Virus is packaged into new complete virons |
| Release (Viral Replication - Step 5) | Departure of new virons from host cell < host cell may rupture OR < host cell remains intact & releases the virus |
| Uncoating | Process of a virus loosing the envelope & capsid |
| Viral Pathogenicity | Two Main Catagories: - Acute Infections - Latent/Persistent Infections |
| Acute Infections | - Disease cycle is relatively short - Host cell ruptures; virus spreads to neighboring cells < Common cold (rhinovirus), influenza, some hepatitis viruses |
| Latent/Persistent Infections | - Virus becomes relatively inactive by reemerges - Provirus remains in host cells - Replicates new virions when triggered by some external event (stress, fever, etc) < Herpes Virus, Epstein-Barr Virus, Human Immunodeficiency Virus (HIV); T-Helper Ce |
| Immune System Viruses | Epstein-Barr Virus (infectious mononucleosis) & Human Immunodeficiency Virus (HIV) |
| Oncogenic Viruses | - Possess oncongenes (cancer causing genes) that cause uncontrolled & abnormal division of host cells by altering cell cycle "checkpoints" < Hepatitis B, Hepatitis C < Human Papilloma Virus (cause of cerical cancer) |
| Oncogenes | Uncontrolled and abnormal division of host cells |
| Interferon | Antiviral therapy which inhibits viral activity |
| Prions | - Infectious proteins w/o genetic material - Come in contact w/normal proteins and transform them into infectious - Affects cells of the brain - Creutzfeldt-Jakob disease ("mad cow") |
| Infectious Particle | Infectious protein which affects the cells of the brain |
| Transmissible Spongiform Encephalopathies | - "Spongiform" = cytopathic effect on brain tissue - "Infection" = produces microscopic holes in brain resembling a sponge |
| Prion Characteristics | - Generally resistant to inactivation by heating to 90* - Resistant to radiation treatments - Not susceptible to enzymes that inactivate RNA & DNA - Susceptible to protein denaturing agents |
| Fungi | - Important for decomposition & recycling - Divided into 2 different groups: < Yeasts = unicellular < Molds = multicellular - Ex.: Candida Albicans (yeast infection) & Tinea Corporis (ringworm, mold) |
| Spores | Small deposits from the enviroment |
| Molds | - Multicellular fungi - One or more spores grows into filamentous, thread-like mass called "mycelium" - Ex.: Athlete's foot, jock itch & ringworm |
| Yeasts | - Unicellular fungi - important in beer, bread, and alcohol production - most common yeast infection: Candida albicans (infections: mouth & pharynx = thrush); vaginitis |
| Protozoa | - Parasites except Helminths (worms) - found in the Kingdom Protista - single-celled organism 2 Different Stages: - Motile trophozoite > infective stage - Cyst stage > dormant state |
| Parasitic Organisms (Protozoa & Helminths) | - Live at expense of host - Transmitted to humans by vectors > Biological = mosquito transmitting malaria > Mechanical = transmission of parasite eggs to food by flies & other insects |
| Helminths | - Known as "worms" - multicellular - found in Kingdom Animalia - 4 Different Groups: > Flukes > Tapeworms > Roundworms > Tissue Parasites |
| Trophozoite Stage | Stage of the protozoa which is the motile, invasive form of the organism |
| Cyst Stage | Stage of the protozoa which allows the organism to survive in a dormant state in the external enviroment |
| Common Pathogenic Protozoans | - Giardia Lamblia: > ingesting cysts from animal contaminated water > intense gastrointestinal (GI) distress & diarrhea - Cryptosporidium: > self-limiting GI symptoms > if infected, can become carrier > recently associated w/recreati |
| Anopheles | Mosquito which serves as the definitive host in Malaria |
| Helminths (Parasitic Worms) | - Hosts are definitive or intermediate > Definitive: harbor parasite when it reproduces > Intermediate: harbor parasite during a developmental stage in the parasite's life cycle > Accidental: not part of the normal cycle; "dead end" hosts |
| Tapeworms | - Segmented worms that contain a head (scolex) and many segments call "proglottids" - Hermaphrodites - Infective stage is larvae found in cattle & swine - Most prevalent in > Beef & Pork (taenia) > Fish (Dibothrocephalus) - Several cm to meter |
| Roundworms (intestinal) | - Live in lumen of intestinal tract - Infection occurs by ingestion of egg or penetration of the skin by larvae > Pinworms (Enterobius) > Ascarids (Giant intestinal worms) > Hookworms |
Created by:
snuzyque
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