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Download MICRO 3050 EXAM 4 CLEMSON QUESTIONS WITH CORRECT DETAILED ANSWERS A+ VERIFIED LATEST UPDAT and more Exams Advanced Education in PDF only on Docsity!
What is a virion? - correct answers-- Complete virus particle (nucleic acid + protein coat + etc) ~10 - 1000 nm in diameter What is a nucleocapsid? What does it mean for a virus to be "naked" - correct answers-- Nucleic acid + capsid (protein coat needed for travel) - Some have envelopes - Naked = no envelope What is viral symmetry referring to? List some types of symmetry - correct answers-- About the CAPSID not the envelope - Helical = in shape of a tube (ex. Tobacco mosaic virus) - Icosahedron = polyhedron, efficiently increases space - Complex = indefinite shape (ex. Vaccinia) - Binal = has both icosahedral and helical (ex. T4) What is the most common viral genome? - correct answers-- dsRNA (some ssRNA) For ssRNA, define positive sense vs negative sense - correct answers-- Positive Sense: Genome and mRNA are the SAME (not a complement) - Take that single piece and use it directly as the message - Can also use reverse transcriptase to make a (-) DNA intermediate - Negative Sense: Genome and mRNA are COMPLEMENTS, has to be negative to make a positive mRNA Describe viral envelopes and the functions of the attachments on them - correct answers-- Outer layer of flexible membrane, derived from host when it buds - Spikes or peplomers are VIRAL derived, come out when budding - Can attach to host cell, function as enzymes, help replicate nucleic acids, ID the virus, help to release/bud the virus List/describe the steps of viral invasion/replication - correct answers-- Attachment: right cell with right receptors - Entry: phages often inject nucleic acid, animal viruses often fuse w/ membrane or get enulfed - Uncoating: can happen during entry - Synthesis: replicate genome, make mRNA and proteins - Assembly: build the virion, pack genome onto capsid - Release: via lysis or budding Describe a viral growth curve. What is the latent period? - correct answers-- Latent period: make early enzymes, take over cell, replicate and synthesize nucleic acid - Outside of cell, nothing is happening Explain lysogeny using lambda as an example? Where does lambda always integrate? - correct answers Host cell is "permissive" and allows viral DNA to incorporate onto its genome (viral DNA becomes a prophage) - Uses integrase to integrate into host chromosome at the attachment site, replicates along with host genome - Lambda integrates between galactose and biotin operons What is a lysogen? What is lysogenic conversion? Give some examples - correct answers-- Lysogen = infected bacterial host that appears normal - Lysogenic conversion = when prophage causes phenotypic change within the host - Ex. LPS of salmonella changes to help invade immune system and prevent other viruses from infecting the same cell - Ex. Diphtheria toxin brought in by prophage and made it more pathogenic What is induction? In lambda, how is it triggered and how does it happen? - correct answers-- Induction = how reproduction is triggered in temperate phage, switches it to lytic cycle - Triggered by drop in levels of lambda repressor (what lambda makes when on the chromosome), and is caused by DNA damage - Excisionase cuts lambda out of chromosome Describe a virulent animal virus and how it affects the host - correct answers-- Virus infects cell, makes virions, lyses the cell - Cause acute infection Describe a latent animal virus and how it affects the host. Give some examples - correct answers-- Lie dormant, can be triggered into replication and lysis - Can either incorporate into chromosome as provirus or be in the cytoplasm - Ex. Herpes simplex virus (activated by stress, cause cold sore) - Ex. Varicella-zoster (chicken-pox as child, then shingles as adult) Describe a persistent animal virus and how it affects the host. Give some examples - correct answers-- Slow budding release of virus that doesn't kill the cell - Cause chronic infection - Cell is compromised but still somewhat functions - Ex. HIV (take over T4 helper cells) - Ex. Hepatitis B Explain the role of viruses in causing cancer (oncoviruses) and give an example - correct answers-- Only the latent viruses that incorporate onto chromosome to cause mutation - Could insert an oncogene and cause rapid division - Could mutate/inactivate a tumor-suppressor gene - Could incorporate onto a proto-oncogene and make it oncogenic - Ex. HPV > Cervical cancer - Called REVERTANTS - Same-site revertant = mutated base pair changes back to wild-type - Second-site revertant = another mutation elsewhere reverts it back to wild-type Define 'screening' - correct answers-- Detecting mutants via observation - Looking for anything, specifically mutants How is 'selection' different from 'screening'? What are 'selectable mutations’? - correct answers-- Put something in a culture medium that will select for growth of the mutants - Selectable Mutation = Mutation that gives an ADVANTAGE to organisms (ex. Antimicrobial resistance) Describe the possible fates of donor DNA during horizontal gene transfer. Which fates end up with stable recombinants? Which ones don't? - correct answers-- Donor DNA could integrate into bacterial chromosome and replicate with it = stable recombinants - Donor DNA could be a plasmid and self replicate = stable recombinants - Donor DNA can't self replicate = No stable recombinants - Donor DNA is cut up by host restriction enzymes = No stable recombinants Describe homologous recombination in bacteria. - correct answers-- DNA strand is nicked via restriction endonucleases - SSB protein protect homologous area from being cut up - RecA (both cells have to be RecA+) binds to DNA and is like a train pulling it along - Enough sequence homology slows it down and then enzymes come in to make a crossover, then it's ligated How do we detect recombinants? - correct answers-- Grow on minimal media after adding recombinant DNA Describe the process of transformation (in general) and the concept of cell competence? - correct answers-- Competent cells uptake naked DNA which then incorporates into host genome - Competence = able to take up DNA Describe generalized transduction? What is a "Transducing particle"? - correct answers-- Only happens during the assembly stage of the lytic phase - Any random part of the host DNA is mistakenly packaged in the virus which is now defective - Virus becomes a Transducing particle Describe specialized transduction? What is lambda-dgal? - correct answers-- Only happens in temperate phages during induction - Prophage is incorrectly excised from the host genome and takes some of the hast genome with it when its packaged - Lambda-dgal = transducing particle (d = defective, g = galactose operon it took with it) Describe the process of bacterial conjugation. What region on the plasmid has the genes for conjugation? What is an 'episome'? - correct answers-- F+ donor sends over a copy of its plasmid to F- recipient (rolling circle method) Describe replicative transposition? - correct answers-- Copy and paste - Transposons replicate a copy of itself and puts itself in another location What is RecA and what is its significance? - correct answers-- Enzyme used for homolagous recombination - Involved in SOS response, stops production of lambda repressor to cause induction - Both the donor and recipient DNA have to be RecAt to have homologous recombination What is tnp? - correct answers-- Transposase, enzyme that recognizes inverted repeats creates staggered cuts to allow transposition Describe PCR and its uses. - correct answers-- Synthesizes large amounts of a DNA fragment to amplify it -ID a species, genotyping, detect mutations, sequencing a genome, cloning, diagnosis, forensics, paternity tests Describe the three steps of PCR? - correct answers-- Denaturing: Target DNA is denatured via heat (hot) - Annealing: Primers bind to target DNA (cold) - Extension: Copies of target DNA are used (Taq polymerase and dNTPs) (hot) Explain how to make a recombinant plasmid using the three steps in molecular cloning. - correct answers-- Isolate gene of interest and vector, cut them up with same restriction endonuclease (fragmentation) - Insert DNA fragment into vector and ligate them - Introduce cloned DNA into host organism via horizontal gene transfer Describe the following tools of the genetic engineer and know how they are used in gene cloning: restriction enzymes, plasmid vectors, and DNA ligase. - correct answers-- Restriction Enzymes: Cut both the vector and the DNA of interest so that the same overhangs are present on both of them - Plasmid Vectors: Is where the DNA is placed so that it can be cloned and observed - DNA Ligase: Seals the DNA and the vector together Describe bacterial plasmids, their significance in a bacterial host, their role in horizontal gene transfer, and their use as cloning vectors. - correct answers-- Small, circular extrachromosomal DNA with “30 non-housekeeping genes - Often transferred via conjugation - Replicate independently of cell, can be manipulated - Can be altered so that foreign DNA is placed into it Know the characteristics of plasmids that make them useful cloning vectors. - correct answers-- Easy to purify, small - Have independent origin of replication (ori) - Have multiple copy number - Have selectable markers (lacZ, ampicillin resistance, etc) - Microbes: gram positive, withstand low water activity, tolerate higher salt concentrations, utilize skin oils for nutrients, mildly acid tolerant - Propionibacteria, Staphylococci Describe the characteristics of the mouth and the microbes there. List some examples. - correct answers-- Saliva has antimicrobial enzymes (lysozyme, lactoperoxidase) - Microbes: colonize teeth and gums, form a BIOFILM (dental plaque), facultative/obligate anaerobes - Streptococci Describe the characteristics of the stomach and the microbes there. List some examples. - correct answers-- Stomach is acidic, ph = 2, often kills most microbes - Helicobacter pylori: Resident, can degrade mucus layer, raise the pH, and cause ulcers Describe the characteristics of the small intestine and the microbes there. List some examples. - correct answers-- pH increases (4-5), volume of bacteria increases - Enterococci, lactobacilli Describe the characteristics of the large intestine and the microbes there. List some examples. - correct answers-- pH = 7, ideal for bacteria - LARGEST microbial population, obligate anaerobes, make essential vitamins (B12, K) and gas, reproduce/replace rapidly - Make up % of fecal matter weight - Bacteroides, Clostridium Describe the characteristics of the respiratory tract and the microbes there. What are some mechanisms of removal there? List some examples. - correct answers-- UPPER respiratory tract (sinuses > larynx) - Lower respiratory tract (trachea > lungs) have NO residential microbes, too small to get in - Removed via mucus made by goblet cells, ciliated epithelial cells pushing them back up, phagocytes, lysozyme in mucus - Staphylococci, streptococci Describe the characteristics of the urogenital tract and the microbes there. List some examples. - correct answers-- Kidney, ureter, bladder = NO microbes - End of urethra = a few microbes, site of UTI when E. coli from feces is introduced - Vagina = Complex microbiota due to hormones - Lactobacillus acidophilus predominates, keeps vagina acidic - Male genital tract is similar to the skin Distinguish between infection and disease. - correct answers-- Infection: Microbe established in/on body and colonizing, growing, not necessarily harmed by it - Disease: Damage to tissues because of microbes Explain how normal microbiota can cause infection and sometimes disease - correct answers-- Some are opportunistic pathogens and cause disease under certain circumstances - If they're placed where they aren't supposed to be, they can cause disease (ex. UTI) - Rapid changes in pH through gastrointestinal tract - Acidic conditions in skin/vagina - Urinary flushing systems - Tight junctions of epithelial cells - WBCs in blood/lymph What causes peptic ulcer disease? - correct answers-Helicobacter pylori What causes chlamydia? - correct answers-Chlamydia trachomatis What causes Ebola hemorrhagic fever? - correct answers-Ebolavirus what causes dengue fever? - correct answers-flavivirus what causes hantavirus? - correct answers-hanatvirus What causes anthrax? - correct answers-Bacillus anthracis what are the characteristics of heliobacter pylori? - correct answers-A very motile, spiral or curved rod shaped Gram-negative bacterium with multiple flagella what are the characteristics of chlamydia trachomatis? - correct answers-an obligate intracellular, Gram- negative bacterium what are the characteristics of ebolavirus? - correct answers-negative stranded enveloped RNA virus what are the characteristics of flavivirus? - correct answers-enveloped positive-sense, non-segmented RNA what are the characteristics of hantavirus? - correct answers-is an enveloped virus with negative and ambisense ssRNA segments (small, medium, and large) how is peptic ulcer disease transmitted? - correct answers-vomit and feces How is chlamydia transmitted? - correct answers-sexually How is ebola hemorrhagic fever transmitted? - correct answers-direct contact with body fluids How is Dengue Fever transmitted? - correct answers-mosquitos How is Hantavirus transmitted? - correct answers-exposure to radent feces (deer mice) How is anthrax transmitted? - correct answers-Inhalation of the spore (pulmonary edema) Contact with the spore Ingestion of contaminated food Use standard isolation precautions while pt is sick what are the symptoms of peptic ulcer disease? - correct answers-epigastric pain, nausea, heartburn what are the symptoms of chlamydia? - correct answers-Urethritis, penile and vaginal discharges, abdominal, rectal, or testicular pain; painful intercourse; irregular menses. - Can cause arthritis and UTI in men and sterility in Woman. 
