BIOS 242 - Final Review 2023 with complete solution questions and answers

Three Domains Archea, Bacteria, Eukarya Hierarchy Domain, Kingdom, Phylum, Class, Order, Family, Genus, Species Zone of inhibition The clear region around the paper disc saturated with an antimicrobial agent on the agar surface. The clear region is an indication of the absence, or the effective inhibition, of microbial growth by the antimicrobial agent. Koch's Postulates 1. The suspected causative agent must be found in every case of the disease and be absent from healthy hosts. 2. The agent must be isolated and grown outside the host. 3. When the agent is introduced to a healthy, susceptible host, the host must get the disease. 4. The same agent must be found in the diseased experimental host. Scientists follow these basic principles when they try to identify the cause of an infectious disease. SEM Microscopy For this microscope, electrons don't pass through the specimen, but focus back and forth across the surface. Gives 3D images TEM Microscopy For this microscope, electrons passing through the specimen create image on a fluorescent screen. Bright Field Microscopy For this microscope, the background is illuminated. The light rays pass through the specimen into objective lens Dark Field Microscopy For this microscope, the light rays scattered by specimen enter the objective lens. The specimen appears light against a dark background Polarized Microscopy This microscope is built like regular optical microscope. Unlike regular microscopes which use normal light, this one uses polarized light to study specimens. Gram Stain components Primary stain (Crystal violet, methyl violet or Gentian violet) Mordant (Gram's Iodine) Decolourizer (ethyl alcohol, acetone or 1:1 ethanol-acetone mixture) Counterstain (Dilute carbol fuchsin, safranin or neutral red) Characteristics of Enzymes 1. Have a high molecular weight 2. Has an amphoteric nature - capable of ionizing either as an acid or as a base depending upon the acidity of the external solution. 3. They are colloid in nature due to which they present a large surface area for reactions to take place. 4. Enzymes are highly specific in nature; a particular enzyme can catalyze only a particular type of reaction 5. Enzymes are heat sensitive - are inactivated or destroyed at temperatures considerably below the boiling point of water. 6. Catalytic properties - enzymes are active in extremely small amounts 7. Like a true catalyst enzymes have been found to accelerate the chemical reaction in either direction (forwards or backwards) Fermentation products ATP, wastes, ethanol, acetic acid, and lactic acid Glycolysis Occurs in the cytoplasm of most cells. The splitting of a six-carbon glucose into two three-carbon sugar molecules (pyruvate). Divided into stages (energy-investment, lysis, energy) Role of oxygen The amount of oxygen present determines the amount of ATP that is going to be produced Biofilm constituents Develop an extracellular matrix composed of DNA, proteins, and tangled fibers of the cells' glycocalyes Characteristics/Morphology of Bacterial Colonies Form - basic shape of the colony (ex: circular) Elevation - cross sectional shape of the colony Margin - magnified shape of the edge of the colony Surface - how the surface of the colony appears (ex: smooth, rough) Opacity - Ex: transparent, opaque, translucent Chromogenesis (pigmentation) - color Interpretation of Microbial Growth Lag Phase - bacteria adapt themselves to growth conditions. It is the period where the individual bacteria are maturing and not yet able to divide. Log (exponential) Phase - is a period characterized by cell doubling. Stationary Phase - period where growth rate and death rate have the same values. Population is neither increasing or decreasing - it is steady. Death (decline) Phase - period where bacteria run out of nutrients and die. Death rate outdoes the growth rate Genetic Code Set of rules by which information encoded within genetic material (DNA or mRNA sequences) is translated into proteins (amino acid sequences) by living cells. Types of antimicrobials Antibiotics, antifungals, antivirals, antiparasitics Clostridium Spore-forming, Gram-positive, anaerobes. Known to produce a variety of toxins, some of which are fatal. C. tetani, C. botulinum, C. perfringens Reservoir An alternate or passive host or carrier that harbours pathogenic organisms, without injury to itself and serves as a source from which other individuals can be infected. Vector An agent, usually an insect or other animal, able to carry pathogens from one host to another. Intermediate Host A host that serves as a temporary but essential environment for parasite development Host An organism that harbors a parasite, or a mutual or commensal symbiont, typically providing nourishment and shelter Portals of Entry and Exit Skin, mucous membranes, placenta, parenteral route Ear, eye, nose, mouth, vagina/penis, urethra, anus Nosocomial infection Any infection acquired while in a hospital or healthcare setting Iatrogenic infection An illness that is caused by a medication or physician Endemic Disease is one that is always present in a population Epidemic Disease that many people acquire over a short period Pandemic World-wide epidemic disease First line of defense Physical and chemical barriers that are always ready and prepared to defend the body from infection. These include your skin, tears, mucus, cilia, stomach acid, urine flow, 'friendly' bacteria and white blood cells called neutrophils. Second line of defense A group of cells, tissues and organs that work together to protect the body. This is the immune system. Antigen composition Proteins that are found on the surface of the pathogen. - unique to that pathogen. When it enters the body, the immune system produces antibodies against it. Northern Plot Technique used for detecting RNA fragments. RNA fragments are treated with formaldehyde to ensure linear conformation. Southern Plot Technique for detecting specific DNA fragments in a complex mixture. DNA fragments are denatured with alkaline solution Western Plot Technique used to detect a particular protein in a mixture. The probe used is therefore not DNA or RNA, but antibodies. Immunoassays - ELISA A test that uses antibodies and color change to identify a substance. Antigens from the sample are attached to a surface. Then, a further specific antibody is applied over the surface so it can bind to the antigen. This antibody is linked to an enzyme, and, in the final step, a substance containing the enzyme's substrate is added. The subsequent reaction produces a detectable signal, most commonly a color change in the substrate. Immunodeficiency Condition that occurs when one or more parts of the immune system are deficient or missing EX: HIV (kills cells of immune system) Autoimmune When your body attacks itself. It sees a part of your body or a process as a disease and tries to combat it. EX: Chron's disease (scarring of GI tract), Grave's disease (overproduction of TH) VRSA Strains of Staphylococcus aureus that have become resistant to the glycopeptide antibiotic vancomycin. Vancomycin is often a treatment of choice in infections with MRSA MRSA Any strain of Staphylococcus aureus that has developed resistance to beta-lactam antibiotics, which include the penicillins (METHICILLIN, dicloxacillin, nafcillin, oxacillin, etc.) and the cephalosporins Control of Microbe growth 1. Alter membrane permeability 2. Damage proteins 3. Damage nucleotides 1. heat 2. low temp (inhibit) 3. high pressure 4. Desiccation (inhibit) 5. Osmotic presure 6. Radiation (nucleic acid, protein damage) 7. Filtration (cant remove viruses. Sometimes endospores) Durham Tube Used in microbiology to detect production of gas by microorganisms. They are simply smaller test tubes inserted upside down in another test tube. This small tube is initially filled with the solution in which the microorganism is to be grown. If gas is produced after inoculation and incubation, a visible gas bubble will be trapped inside the small tube. Special media Media that allows certain growth depending on the type it is. Ex: may allow growth of some microorganisms and not allow growth of others Staphylococcus Gram-postive cocci, nonmotile, faculative anaerobes, salt-tolerant; treat with methicillin or vancomycin Bacillus Gram-positive bacilli, occur singly, in pairs, or in chains, form endospores; contract via inhilation/ingestion of spores; treated with antimicrobial Clostridium Gram-positive, anaerobic, endospore-forming Listeria Gram-positive, non-spore-forming, coccobacillus; found in soil, water, mammals, birds, fish, and insects; enters via contaminated food and drink; treated with antimicrobial Neisseria Gram-negative cocci, nonmotile, aerobic bacteria, arranged as diplococci, oxidase positive Exotoxin Toxic substances secreted by bacteria and released outside of the cell. Endotoxin Bacterial toxins composed of lipids that are within a cell. Simple stain Shows the basic morphology of the bacterium or bacteria present Differential stain Done to determine if a bacterium is gram positive (purple) or gram negative (pink/red) Stages of Mitosis Interphase - DNA has replicated, but has not formed the condensed structure of chromosome. They remain as loosely coiled chromatin. Prophase - The DNA molecules progressively shorten and condense by coiling, to form chromosomes. The nuclear membrane and nucleolus are no longer visible. The spindle apparatus has migrate to opposite poles of the cell. Metaphase - The spindle fibres attach themselves to the centromeres of the chromosomes and align the the chromosomes at the equatorial plate. Anaphase - The spindle fibres shorten and the centromere splits, separated sister chromatids are pulled along behind the centromeres. Telophase - The chromosomes reach the poles of their respective spindles. Nuclear envelope reform before the chromosomes uncoil. The spindle fibres disintegrate. Stages of Bacterial binary fission 1. DNA is copied, 2. New cell membrane is added to apoint on the membrane between the two DNA copies, 3. The growing cell membrane pushes inward , and the cell is consticted in two, 4. New cell wall forms around the new membrane, 5. The bacterium is pinched into two independent cells. Natural Acquired Immunity Immunity where there is natural exposure to an infectious agent or other antigen by the body. The body responds by making its own antibodies. Artifical Acquired Immunity Immunity where any immunization with an antigen is given. The body will produce its own antibodies and develop circulating, long-lived B-memory cells Virulence factor Enable a host to replicate and disseminate within a host in part by subverting or eluding host defenses. Ex: capsules, endotoxins, pili/fimbrae Modes of pathogenicity Contact transmission (direct, inderect, droplet) Vehicle transmission (airborne, waterborne, foodborne) Vector transmission (biological or mechanical) Candida infection manifestations (Oral) White spots inside the mouth and on the tongue, Redness or discomfort in the mouth area, Sore throat and difficulty swallowing, Cracking at corners of the mouth where your lips meet (Genital) Extreme itching in the vaginal area, Soreness and redness in the vaginal area, White, clumpy vaginal discharge that looks like cottage cheese, Painful intercourse --- Red rash on penis, Itching or burning on the tip of the penis DNA virus Stable since it is double stranded. Less prone to damage because it does not replicate as fast. They are hard to treat, but may be easier to treat since the virus is steady. RNA virus Unstable since it is single stranded. There is a higher chance for damage because of the instability. Is classified into categories to help determine types of viruses (+ssRNA, -ssRNA, dsRNA, retrovirus); Can mutate faster because instability allows for chance of change Plant Virus A virus particle, also known as a virion, is an extremely small infectious agent. It is essentially a nucleic acid (DNA or RNA) enclosed in a protein coat called a capsid. Viral genetic material can be double-stranded DNA, double-stranded RNA, single-stranded DNA or single-stranded RNA. They produce symptoms such as ringspots, mosaic pattern development, leaf yellowing and distortion, as well as deformed growth. Animal Virus Animal viruses are intracellular obligate parasites, meaning that they rely on the host animal cell completely for reproduction. Fungus life-cycle A haploid phase alternates with a diploid phase. The haploid phase ends with nuclear fusion, and the diploid phase begins with the formation of the zygote (the diploid cell resulting from fusion of two haploid sex cells). Meiosis (reduction division) restores the haploid number of chromosomes and initiates the haploid phase Motility test The purpose of this test is to see if the microbe can "swim" by means of flagella Carbohydrate metabolism test Tests to determine if a microorganism can utilize carbohydrate break down for energy Helminths Macroscopic, multicellular, eukaryotic worms; Three groups - cestodes (tapeworm), trematodes (fluke), and nematodes (roundworm) Peptidoglycans AKA murein, is a polymer consisting of sugars and amino acids that forms a mesh-like layer outside the plasma membrane of bacteria (but not Archaea), forming the cell wall. Endospores A dormant, tough, non-reproductive structure. The primary function of most is to ensure the survival of a bacterium through periods of environmental stress.