Microbiology Exam 2

  1. List the 3 ways that bacteria get new DNA
    • transformation
    • transduction
    • conjugation
  2. Why do prokaryotes need these extra ways of getting DNA
    because it helps them gain genetic variability and since they are so simple and don't reproduce sexually, their variability is limited
  3. Gene transfer
    prokaryotic cells transfer DNA from Donors to recipients
  4. Recombination vs recombinant
    • recombination: combining DNA from different sources
    • recombinant: the resulting cell that has genes from different sources
  5. Human gene transfer vs bacterial gene transfer
    • humans: vertical gene transfer to offspring only
    • bacteria: lateral or horizontal gene transfer to another organism in the same generation
  6. Virulent
    • causes disease
    • virulence factor: makes it more dangerous ie a capsule
  7. Transformation
    • Genetic material is taken up from bacteriums surroundings (if theres DNA in the environment)
    • single stranded fragments are taken up by competent cells and inserted directly into the bacterial chromosome
    • first discovered in smooth vs rough colonies of streptococcus pneumoniae
  8. Discovery of Transformation
    • Frederick Griffifth looked at "smooth" and "rough" colonies of strep pneumo
    • smooth colonies contain a capsule and are virulent
    • rough colonies dont have a capsule and dont cause disease.
    • He injected killed smooth bacteria into mice and they did not die
    • also injected live rough bacteria into the mouse and it lived
    • but when live smooth bacteria injected to the mouse it died as expeced since this is virulent
    • However, an injected combination of killed harmful smooth and live harmless rough killed the mouse.. why? The rough took up the DNA released when the smooth was killed and gained virulency
  9. Can all bacteria undergo transformation
    • no, only competant bacteria
    • some have a "competence factor" that is released into the medium prior to transformation which allows them to open up to DNA fragments
    • biologists can buy competent bacteria to transform
  10. Transformation diagram
    Image Upload 1
  11. Transduction
    • bacteriophages introduce genetic material through transduction
    • 2 types of phages
  12. 2 types of phages
    • Virulent Phage
    • Temperate Phage
  13. Virulent Phage
    • Cause infection and eventual death (by lysis) of the bacterial cell
    • uses the lytic cycle
  14. Temperate Phage
    • infect bacterial cells but go into lysogenic phase where they insert their DNA into the bacterial chromosome (now called prophage) and do not lyse the cell open immediatedly
    • virus DNA exists in the bacterial chromosome
    • temperate phage can later be induced to go into a lytic phase, make copies of themselves then lyse the cell open to infect neighboring cells
    • during this process sometimes bacterial DNA is taken out during prophage excision and transferred to other bacterial cells during subsequent phage infections
  15. Lytic cycle
    • absorption: virus binds cell
    • entry: virus injects DNA into cell
    • replication: more virus are made in the cell, virus has overtaken cell machinery
    • assembly
    • release: viruses lyse the cell and go to infect other cells
  16. lysogenic cycle
    • longer sneakier cycle
    • Virus binds and injects DNA, which sneaks into bacterial chromosome, bacteria continues to replicate and therefore replicating this viral DNA as well, eventually they can undergo induction and enter the lytic cycle
  17. induction
    switch from lysogenic to lytic cycle
  18. prophage
    viral dna that is existing within the bacterial chromosome
  19. 2 types of transduciton
    • generalized transduction
    • specialized transduction
  20. generalized transduction
    • lytic cycle
    • we have a virulent phage, it injects the DNA, takes over the (donor) host cell machinery to make viral DNA and more protein coat
    • the host chromosome is fragmented into pieces during replication and when new viruses are packaged some have viral DNA and some have host DNA
    • the ones with host DNA (defective phages) will transfer bacterial DNA from one to another when it goes to infect a new cell
    • viruses escaping to infect new cells have EITHER host (pure host DNA) or viral DNA
  21. Defective phage
    virulent phage that was packaged with host DNA
  22. Specialized transduction
    • Undergoes lysogenic cycle
    • virus injects DNA into donor bacterial host cell. viral DNA becomes incorporated into the bacterial chromosome (a prophage)
    • replication occurs and eventually induction, and when the cell lyses,the viruses escaping to infect new hosts have BOTH viral and bacterial DNA
  23. Describe the gerneralized transduction flow chart
    • host bacterial cell has chromosome with genes A+ and B+.
    • Virus infects host cell and Host DNA is hydrolyzed into pieces
    • phage DNA and proteins are made in the host cell
    • occasionally, a bacterial DNA fragment (in this example, a fragment containing the A+ gene) is packaged into a phage capsid
    • that phage capsid infects another bacterial host cell (this one is A- B-) and inserts that A+ DNA, Crossing over occurs and Image Upload 2 now the new cell is A+ B-
  24. Describe the specialized transduction flow chart
    • The bacteriophage infects the host A+B+ cell and its dna becomes incorporated into the host chromosomal dna between genes A and B
    • the prophage DNA will usually exit the chromosomal to be packaged into the new virus capsids, but occasionally, prophage DNA exits incorrectly, taking adjoining bacterial DNA with it (in this case the A+ gene)
    • The phage particals carry the bacterial DNA along with phage DNA
    • When the phage infects a new A-B-cell, there is still phage DNA inserted, but that A+ gene is crossed over into the chromosome, transferring this geneImage Upload 3
  25. Conjugation
    • uptake of genetic material from neighboring bacterial cells
    • requires contact between donor and recipient cells
    • can transfer larger pieces of DNA, even whole chromosomes
  26. how is dna passed in conjugation from donor to recipient?
    • passed through "F pilus" or "sex pilus" or "conjugation pilus"
    • pilli are specific to prokaryotes, they form a bridge
  27. F plasmids
    • aka: fertility plasmids
    • conjugative plasmids that contain genes for generation of a pillus, so when transferred it can make a cell that cant conjugate able to
    • accessory DNA 
    • F+ is the donor (male)
    • F- is the recipient (female)
    • allow the transfer of genes
  28. What can plasmids do
    • direct synthesis of conjugation pilli
    • provide resistance to certain antibiotics
    • induce the formation of tumors in plants
  29. describe conjugation from F+ to F-
    • The donor cell contains the F plasmid along with the chromosomal DNA
    • the donor forms a conjugation bridge with pili and a single strand of the plasmid goes across
    • replication then happens so that both plasmids are double stranded
    • F- is now F+
  30. What will the outcome be if you put F+ and F- cells on a plate
    eventually they will all become F+
  31. High frequency recombinations
    • called Hfr cells
    • come from F+ strains where the plasmid is incorporated into the bacterial chromosome rather than seperate
    • can initiate some chromosomal DNA to be transferred along with the F Plasmid
  32. Hfr cell
    • A cell where the f plasmid has integrated into the bacterial chromosome
    • during conjugation a single strand of the plasmid and some chromosomal DNA moves to the F- cell, crossing over will occur and that piece will be integrated into the F- cell dna creating a new Hfr Cell
  33. F' Plasmids
    • sometimes an F plasmid that is incorporated into the chromosome can detach and once again become an F plasmid
    • However, if it takes a long piece of chromosomal DNA with it, it is now called the F' plasmid because it differs genetically from the original F plasmid.
    • the cell may not be able to function at all if the plasmid takes out an essential gene
    • F- can get extra copies of genes if conjugation happens this way
  34. F' conjugation flow chart
    • plasmid is integrated into chromosomal DNA
    • becomes an F' plasmid when it comes out of chromosomal DNA and brings genes A and B with it. 
    • conjugation occurs and a single strand of the f' plasmid containing these genes goes to the F- cell and they both replicate
    • F- cell now has duplicate copies of genes A and B
  35. Transposons
    • resistance genes often found on a resistance plasmid
    • can move around from plasmid to plasmid and sometimes incorporate into the bacterial chromosome
    • move in groups 
    • contain transposable elements and another unrelated gene that is moved from place to place
  36. Transposition
    the ability to move from one location to another with regards to transposons
  37. Transposable elements
    • genes that can move around by transposition
    • made up of: 1. genes that code for transposase 2. genes that are surrounded by inverted base repeats
  38. Transposase
    enzyme that aids in transposition
  39. Diagram of a transposon
    Image Upload 4
  40. Genetic Engineering
    • the purposeful manipulation of genetic material to alter the characteristics of an organism in a desired way
    • transfer of genes between different species is possible in the lab
    • altering genetic material to get certain characteristics
  41. Genetic Fusion
    • transposition of DNA from one location on a chromosome to another
    • if the control genes for one operon are moved in front of another operon, both sets of genes will be controlled together

    • ie: Regulator gene---promoter--operator-5-4-3-2-1---regulator gene---promoter-operator-z-y
    • second regulator gene promoter and operator transposed out and what remains, the first regulator gene controls production of it all
    • regulator---promoter--operator-5-4-3-2-1-z-y
  42. Protoplast
    an organism where the cell wall has been removed
  43. Protoplast Fusion
    • two protoplasts can fuse and mix their genetic material, recombining two strains before the cell wall reforms
    • useful in making genetically modified organisms (gmo)
  44. Gene amplification
    • making lots of copies of a gene and therefore lots of product
    • plasmids or bacteriophages produce rapidly within a bacterial cell
    • used to make antibiotics, enzymes, amino acids
  45. Recombinant DNA technology
    • DNA contains info from two different species
    • if the DNA integrates into the sperm or egg cell DNA, all offspring will contain the gene as well. These offspring are termed "transgenic" or "recombinant"
  46. Requirements to make a transgenic bacteria
    • 1. invitro manipulation of DNA
    • 2. recombination of another species DNA in a  bacterial phage or plasmid (vector)
    • 3. cloning, or increased production of many genetically identical offspring of phage or plasmids (so we can harvest the protein)

    bacteria or animals can be transgeneic
  47. restriction endonuclease
    • named because they restrict bacteriophage division by chopping up phage DNA
    • molecular scissors that let us cut a gene out of DNA and insert it elsewhere
  48. Process of creating a transgenic organism
    • 1. DNA from one organism is cut into small segments using a restriction endonuclease
    • 2. The same restriction endonuclease is used to cut the recipient vector
    • 3. The DNA is incorporated into the vector using ligase
    • 4. The finished vector is used to transform bacterial cells by heat shock or electroporation
  49. Electroporation
    a high voltage discharge is used to make bacteria temporarily permeable to take up DNA
  50. Draw the chart of recombination DNA technology
    Image Upload 5
  51. 4 medical applications of recombinant DNA
    • Make substances important to humans: interferon (interrupts virus infection), insulin (treats diabetes), blood products (for hemophiliacs- clotting factors), enzymes, antigens for vaccines
    • Diagnosis of genetic defects in fetuses
    • Gene Therapy: very successful, tailored to the individual. inserting functional genes into appropriate cells to cure a genetic disease
    • Forensic Science
  52. 5 Industrial applications of Recombinant DNA
    • 1. Fermentation of wine, beer
    • 2. Degradation of normally useless plant material (cellulose)
    • 3. Fuel manufacturing
    • 4. Clean up of environmental pollutants (ie oil spills)
    • 5. Extraction of metals from ore
  53. 4 Agricultural Applications of Recombinant DNA
    • Control insects that destroy crops and mosquitoes
    • high yeild seeds
    • resistance to weed herbicides
    • nitrogen fixation
  54. Hybridomas
    • Used in medical application
    • fusion of two cell types
    • first was the fusion of a myeloma cell (bone marrow cancer cell) with a B cell that makes antibodies- allows rapid pure antibody production which you can inject to treat disease
  55. Is recombinant DNA safe? Why
    • YES!
    • 1. no lab workers have become ill because of known recombinant organisms
    • 2. The lab strain of E.coli used in lab does not infect humans
    • 3. Mammalian genes incorporated into E.coli make the bacteria less adaptable
    • 4. Using a normal level of lab safety is considered sufficient to control mutant e.coli
  56. Taxonomy
    • the science of classification
    • taxonomists look at evolutionary relationships to see how related 2 things are
  57. Reason for standardized names
    • criteria for identifying organisms
    • arrange related organisms into groups
    • provide information about evolution
  58. Whats the idea of taxonomy
    • Members of higher level groups share fewer characteristics
    • members of lower level groups are more alike
  59. Linnaeus
    • the father of taxonomy
    • created binomial nomenclature (it used to be 5 names)
  60. Binomial nomenclature
    • every organism has 2 names- genus and species
    • species is NEVER CAPITALIZED
    • both are written in italics OR underlined
  61. Strains
    • within a species, there can be different strains of bacteria
    • contain a genetic difference or mutation that distinguishes them from other members of the species
    • ex: resistance to abx, presence of an antigen, need for particular nutrient
    • E.coli K12- studied for plasmids
    • E.coli 0157:h7- hemmorrhagic inflammation of colon
  62. Classification levels
    • Kingdom
    • Phylum (and sometimes subphylum)
    • Class
    • Order
    • Family
    • Genus
    • Spaghetti 
    • KingPhillipCameOverForGoodSphaghetti
  63. Dichotomous Key
    • used to identify organisms in the world
    • asks yes or no and if then questions
    • ie: is it gram positive? if yes go to #2 if no go to #3. 
    • will only get you so far, gives an initial identification, good for nature hikes identifying plants and such
  64. How are animal species defined
    • they are a species if they are capable of DNA transfer during mating to fertile offspring
    • ie- lyger is not a species because a lion and a tiger make it but it is not fertile
  65. Why doesnt the way animal species are defined work for bacteria
    because bacteria reproduce by binary fission and the only DNA transfer is during recombination
  66. How are bacteria seperated into species
    • according to:
    • 1. biochemical reactions (biproducts from metabolism)
    • 2. chemical composition
    • 3. cellular structures
    • 4. genetic characteristics
    • 5. immunological features that identify an organism to our immune system (how they affect us)
  67. What are the 3 domains
    Bacteria, Archaea, Eukarya
  68. What are the 5 kingdoms
    • plantae
    • animalia
    • fungi
    • protista
    • monera
  69. Kingdom Monera
    contains all prokaryotes
  70. Types of prokaryotes
    • Eubacteria
    • Cyanobacteria
    • Archaebacteria
  71. Eubacteria
    • true bacteria
    • includes pathogens
  72. cyanobacteria
    photosynthetic autotrophs (self feed)
  73. Archaebacteria
    • ancient bacteria that live in the harshest of environments (high temp, pressure, salt, etc)
    • cell wall and RNA polymerase are different from eubacteria (different composition)
  74. Examples in kingdom monera
    • mycoplasma
    • cyanobacteria
    • spirochetes
    • gram negtive bacteria
    • rickettsias
    • archaeobacteria
    • gram positive bacteria
  75. Kingdom Protista categories
    • euglena
    • diatom
    • dinoflagellate
    • ciliate (paramecium)
    • sarcodine (amoeba)
    • mastigophoran (trypanosoma- african sleeping sickness)
    • apicomplexan (plasmodium- ie malaria)
  76. Kingdom Fungi categories
    • sac fungi- morchella
    • club fungi- amanita muscaria
    • algae like fungi- pilobolus
    • molds- penicillium (produce pennicillin)
  77. Kingdom Plantae
    • A couple of drugs come from them ie quinine from the cinchona tree
    • otherwise not very related to micro
  78. Kingdom animalia
    • insects
    • arthropods
    • vertebrates
    • nematodes
    • platyhel minths (worms)
  79. 3 types of archae bacteria
    • Methanogens
    • Extreme Halophiles
    • Extreme Thermoacidophiles
  80. Methanogens
    • anaerobic
    • make methane
    • landfills have pipes that are venting methane out that the bacteria are producing
  81. Extreme halophiles
    • obligate aerobes
    • live in high salt conditions
  82. Extreme thermoacidophiles
    • found in hotsprings, hydrothermal vents under the ocean
    • contain extremozymes
  83. Extremozymes
    • enzymes that allow high temp toleration, non denaturing
    • Scientist took extremozymes from these bacteria to do PCR to amplify DNA
  84. Classification of viruses
    • acellular infectious agents
    • contain nucleic acids (rna or dna) and protein coats
    • not alive, therefore do not belong to any kingdom
  85. Why is evolution of prokaryotes difficult to study?
    • they evolve quickly because of short generation time
    • similar morphology
    • hardly any fossil record because theyre so tiny
  86. numerical taxonomy
    • organisms are observed for as many characteristics as possible
    • values of 1 are given if present 0 if not present
    • computers analyze numerical data to detect patterns
    • greater than 90% match means 2 organisms are in the same species
    • harder than it seems to do
  87. Genetic Homology
    • Studies the similarities of DNA between organisms
    • sequencing is improving knowledge of organisms, but is costly and time consuming
  88. Types of Genetic homology tests
    • Base composition
    • DNA/RNA sequencing
    • DNA hybridization
    • Protein profiles
  89. Base composition
    • A T C G bases: look at G and C content. 
    • Varies from 23%-75% in different bacterial species
    • same GC content does NOT mean they are related, but different G-C content means they are NOT RELATED
  90. DNA/RNA sequencing
    probe for unique DNA sequences
  91. DNA hybridization
    • taking DNA from 2 organisms and sticking it together to see if the strands stick together. 
    • identical DNA sequences will anneal to eachother
    • the more they stick the more similar they are
    • if unrelated, very little annealing occurs
  92. Protein profiles
    • PAGE
    • measures size of proteins
  93. Other ways of determining similarities
    • properites of ribosomes
    • immunological reactions
    • phage typing
  94. Properties of ribosomes
    • ribosomes evolve slowly bc we need the proteins to be made correctly so if the ribosomes change we risk changing the protein which could kill the cell
    • compare 16s ribosomal rna between organisms
  95. immunological reactions
    • use antibodies to stick to particular surface proteins
    • if bacteria have similar antigens theyre related
    • western blot
  96. phage typing
    • determins which bacterial viaruses attack particular organisms
    • viruses have to be able to stick to the cell before they can infect. they only bind to certain types of cells
  97. How does a virus replicate
    • obligate intracellular parasites
    • must get into a host cell and use its machinery
  98. What is a virus
    • Contains RNA or DNA but NOT both
    • invades a host cell, takes over the machinery to replicate
    • doesnt last long outside the cell
  99. virion
    one virus particle
  100. parts of a virion
    • nucleic acid core
    • protein capsid
    • some virions have envelopes
  101. nucleic acid core
    RNA or DNA in the virus
  102. Protein Capsid
    • a protein coat that protects the viral genome (genetic info)
    • determines shape of the virus
    • has subunits
  103. Capsomeres
    • subunits of the capsid (look like nuts and bolts)
    • make up the capsid
  104. Envelope
    • some viruses have outer envelopes
    • made of bilipid layers that are "stolen" from the host cell as the virion particles burst open the cell
    • covers them and makes them look invisible to new hosts since they are made of the same material
    • allow viruses to get in cells and hide from our immune systems
    • help new virions to infect other host cells
  105. Label the virus
    Image Upload 6
  106. Naked vs enveloped viruses
    • non enveloped, or naked viruses are more virulent
    • the envelope makes the virus more susceptable to temperature and pH changes
  107. what is the envelope made of
    • lipids, proteins and carbohydrates
    • the same as our lipid bilayers
    • contain spikes
  108. spikes on the envelope
    • glycoproteins that project from the surface
    • allow virions to bind to a host cell by binding receptors on the cell
  109. how do envelopes help virions infect new host cells
    by fusing with the host cell membrane
  110. Virion Shapes and examples
    • helical: spiral of protein around core; ie tobacco mosaic virus
    • polyhedral: many sides, looks geometric; ie adenovirus
    • complex: some capsomeres are helical and others are polyhedral; ie tailed bacteriophage
    • bullet: looks like a bullet; ie rabies
    • thread: thread like; ie ebola
  111. give an example of a type of polyhedral virus
    icosahedral has 20 sides
  112. Rabies Virus
    • bullet shaped
    • has lipoprotein envelope
    • knoblike spikes (glycoprotein S)
    • genome unsegmented
    • Linear negative sense RNA
  113. what do viruses infect
    depends on the host range and viral specificity
  114. Host range and example of it
    • types of hosts a virus can infect
    • most viruses can only infect one type of animal, plant, fungus, protist or bacterium
    • ie- the polio virus only causes disease in humans
    • some can jump species but many are species specific
  115. Viral specificity
    • the type of cell a virus can infect
    • dependent on the specific enzymes and proteins made by the host cell to aid in viral replication
    • also depends on the ability of the virions to escape the host cell and infect other cells
  116. how is viral specificity determined
    • by the ability of a virion to attach to the host cell
    • depends on the proteins made by the host cell and how well the virus can escape that type of cell to infect more
  117. What determines if a virus can attach to a specific host cell
    attachment depends on the receptor sites on the host cell and attachement sites on the capsid or envelope of a virus
  118. examples of virus specificity
    • papilloma virus can only infect skin cells (causes warts)
    • in contrast, cytomegalovirus (CMV) can infect cells of the salivary glands, GI tract, liver, lungs, etc and can cause varied symptoms throughout the body depending on which cells are infected
  119. how to think of host cells and virus
    • the virus is a key and the host cell is a lock, it is very specific
    • although some (ie CMV) can infect many differernt types of cells
  120. how can viruses be classified
    • by the number and arrangement of proteins in the capsid
    • can also be categoriezed by whether its an RNA or DNA virus
  121. How did viruses evolve (multiple theories)
    • because they need host cells to replicate, some believe they probably came on the scene after primitive cells evolved
    • some think viruses and cells evolved together
    • some think they were once real cells
    • some think they evolved from bacterial plasmids
    • some think they were the precursers of cells
  122. Taxonomy of viruses (older)
    • originally based on the type of host a virus could infect (usually categorized this way) ie plant virus, animal virus
    • then on which area of the organism was infected (pneumonic, neurotropic)
  123. taxonomy of viruses (more recent)
    • more recently, viruses have been classified by their genetic structure
    • RNA viruses vs DNA viruses
  124. RNA Viruses
    most are single stranded and have either a positive or negative sense strand
  125. Sense strand
    part of RNA viruses that has to do with how virus gets proteins
  126. + Sense strand and example
    • acts as mRNA
    • RNA can be used immediately to make proteins by host ribosomes
    • HIV is an ex. + sense strand converted to DNA by reverse transcriptase then to RNA by the host cell polymerase
  127. - Sense strand
    • a complimentary RNA strand must first be made in order to be used by the host ribosomes
    • - sense RNA viruses must also carry their own enzyme for making the complimentary strand (RNA polymerase)
    • - sense strand; complimentary mRNA made from this that can be translated into protein by the host cell
  128. Common RNA viruses
    • Picornaviridae
    • Retroviridae
  129. Virulent vs Temperate
    these names only apply to bacterialphages, although there are viruses that infect other organisms that can hide in the cell
  130. Picronaviridae and types with examples
    • icosahedral viruses with + sense strand, no envelope
    • enteroviruses: polio virus
    • rhinoviruses: nose cold, common cold
    • hepatociruses: "liver" hepatitis A
  131. Retroviridae
    • retroviruses
    • ie: HIV
    • 2 copies of + sense RNA 
    • contain reverse transcriptase
    • the viral DNA can get into the host cell nucleus and integrate or hide there
  132. reverse transcriptase
    enzyme that converts RNA to DNA for a retrovirus inside the host cell
  133. HIV transcription
    + sense strand transcribed into DNA by reverse transcriptase which sneaks into the host DNA and stays there for years and will be transcribed to mRNA and protein in the cell
  134. why do summer colds feel different than winter ones
    different viruses infect at different times
  135. Common DNA viruses
    • Adenoviridae
    • Herpesviridae
    • Papovaviridae
  136. Adenoviridae
    • "gland"- affect glands
    • extremely resistant to heat, pH or chemicals
    • cause respiratory symptoms and severe diarrhea in humans
  137. Herpesviridae and disease examples
    • "creeping" family
    • they can hide and be latent then come out later
    • different family members cause many diseases
    • oral herpes, genital herpes, chicken pox, shingles, lymphoma, hodgkins disease, b cell lymphomas
    • Kaposi's sarcoma
  138. Papovavirdae
    one member of the family is papilloma virus (HPV) which is responsible for most instances of cervical cancer
  139. virus vaccine
    contains parts of the virus or an attenuated virus
  140. Viral replication steps
    • 1. Adsorption: attachement to host cell (sticks to it)
    • 2. Penetration: entry into the host cell (DNA is inserted and now it can take over the host machinery)
    • 3. Synthesis: generation of viral nucleic acid and capsid proteins using host cell machinery
    • 4. Maturation: assemply of new virions from these pieces (capsids, proteins, etc)
    • 5. Release: escape of new virions from cells to infect others, often destroys host cell by lysis
  141. Steps of bacteriophage replication
    • 1. Adsorption
    • 2. Penetration
    • 3. Biosynthesis
    • 4. Maturation
    • 5. Release
  142. Adsorption (bacteriophage)
    phage is adsorbed onto bacterial cell wall
  143. Penetration (for bacteriophage)
    • phage penetrates bacterial cell wall and cell membrane
    • phage DNA is injected
    • bacterial DNA is disrupted/fragmented
  144. Biosynthesis (for bacteriophage)
    • the phage DNA directs the cells metabolism to produce viral componenets- proteins and copies of phage DNA
    • empty phage heads and pieces of phage DNA are synthesized
  145. Maturation (for bacteriophage)
    • collars, sheaths, and base plates have been attached to the heads.
    • tail fibers are added last
  146. release (for bacteriophage)
    bacterial cell wall lyses, releasing mature phages.
  147. Plaque assay
    • a way to determine the numbers of bacteriophage
    • serial dilutions are made from a suspension of phage
    • each dilution is added to a bacterial lawn on a nutrient plate
    • when phage gets into bacteria it will replicate and then lyse it and infect surrounding cells. bacterial cell lysis will form a clearing of bacterial cells whereever the original phage infected
    • counting the plaques will tell you how many phage you started with when x by the DF
    • # reprisented in PFU
  148. PFU
    plaque forming units
  149. What triggers induction when a phage switches from lysogenic to lytic
    • environmental or chemical triggers
    • ie- UV  radiation
  150. Lytic cycle summariezed again
    • virus attaches to a specific host cell and injects DNA or RNA into the cell.
    • the cell then takes that genetic material and makes so many copies that eventually cause lysis and death
  151. Stages of the lysogeny bacteriophage cycle
    • 1 &2- Adsorption and Penetration: phage is adsorbed to receptor site on bacterial cell wall, penetrates it and inserts its DNA; phage DNA inserts itsef as a prophage into bact. chromosome and is replicated along with the bacterial DNA; binary fission occurs and both daughter cells have phage DNA
    • 3. Biosynthesis: the phage DNA directs the cells metabolism to produce viral components; empty phage heads and pieces of phage DNA 
    • 4. Maturation: heads are packed with DNA; collars, sheaths, base plates attach to heads and then tail fibers added
    • 5. Release: bacterial cell lyses relasing completed infective phages
  152. Describe the replication of animal viruses
    • 1. Adsorption and fusion with the cell membrane (easier if the virus has an envelope)
    • 2. Penetration- enters the cell and uncoating (Protein coat lost and its just the DNA/RNA)
    • 3. DNA/RNA enters host cell nuclear membrane and the viral genes are transcribed by host cell machinery
    • 4. Viral DNA is replicated and translation makes viral coat proteins (capsid)
    • 5. Maturation- New virus particles are assembled
    • 6. Release- some viruses bud out from the host cell and become covered by envelope protein stolen from the host cell; others acquire envelope as they emerge from the nucleus or while theyre in the cytoplasm
  153. Study Virus Replication diagrams
  154. How do viruses recognize the cells they infect?
    • No envelope: a canyon (dip between capsomeres) on the virus will match up with host plasma membrane proteins like a key for binding; it must match in order to stick
    • With envelope: viral glycoprotein (spikes) on the membrane will bind the membrane protein receptors on the host cell
  155. What is a way to study viruses
    cell culture- growing cells in a flask
  156. types of cell culture
    • primary cell culture
    • dipoid fibroblast strains
    • continuous cell line
  157. primary cell culture
    • cells come directly from an animal
    • can last only a short time in culture because of limited cell division
  158. Why do normal cells have limited number of divisions
    • eventually, cells age out
    • telomeres on the chromosome have repeating sequences that protect the ends of the chromosome
    • with every division, small pieces of the telomere are lopped off until its gone, then what's left to be chopped is chromosomal DNA so the cell can't divide anymore
  159. DIploid fibroblast strains
    • cells that make connective tissue
    • derived from fetal tissue so they divide longer in culture
    • used for making vaccines
  160. Continuous cell line
    • cells will reproduce for an extended time
    • HeLa cells
    • Immortal cell line because they will divide indefinitly in culture
    • continuous cell lines are not normal cell lines, usually cancer
  161. HeLa
    Henrietta Lacks' cervical cancer cells were taken without her knowldege and John Hopkins sent to George Guy who did many studeis
  162. Why could Henriettas cells divide indefinitely
    she had an enzyme that regenerated her telomeres
  163. Teratogen
    • something that causes defects during embryonic development
    • if you're pregnant avoid these and take precautions
    • some viruses can be teratogens if they are transmitted across the placenta
  164. Examples of teratogens
    • CMV: causes neurological defects
    • Herpes Simplex 1 and 2: Acquired during birth process if infant touches an outbreak, can damage eyes and nervous system
    • Rubella: can cause deafnes, heart defects, mental retardation
  165. how can doctors avoid newborns from getting herpes
    if there is a flare up near delivery they'll do a c section so baby doesnt touch it
  166. Viriods
    • smaller than a virus, cannot replicate itself
    • consists of single circular RNA
    • no capsid or envelope
    • do not require helper virus
    • doesn't produce proteins
    • RNA can be copied only in host cell nucleus
    • only known to affect plants
  167. Prions
    • acellular misshapen proteins
    • not viruses or caused by viruses, just misshapen incorrectly folded proteins
    • proteinaceous infectious particle
  168. PrP
    • prion proteins
    • tend to stick together inside cells which is fatal to the cell
  169. Why are prions dominant
    • because they induce normal protiens to fold incorrectly as well
    • they can cause the membrane proteins of cells near them to misfold and get in and cause a chain reaction
  170. Prion examples
    • Creutzfeldt Jakob Disease: fatal neurodegenerative disorder (occurred during surgery with equipment contamination)
    • Kuru: natives of New Guinea, due to cannibalism?
    • Scrapie: mad cow for sheep
    • Mad Cow disease: bovine spongiform encephalopathy
  171. Why are prions hard to treat (5 reasons)
    • resistant to high temps that would kill a virus
    • cannot be treated with radiation that would damage the nucleic acids of a virus
    • not destroyed by nucleases (enzymes that break up RNA and DNA)
    • have direct pairing of amino acids
    • can cross species
  172. How are prions treated
    • they are resistant to normal sterilization/heat
    • need a very strong chemical that denatures proteins to remove
  173. How does prion disease spread (in mad cow disease?)
    • cows were given feed containing "protein supplements" which came from brain matter of sheep
    • some of these sheep had scrapie
    • prions were passed up the food chain from sheep to cows to humans
    • prions are NOT species specific
  174. Cancer
    • unregulated invasive growth of abnormal cells
    • chromosome # can be abnormal too
    • cells that do not stop growing as they are supposed to can build up locally inot a neoplasm
  175. neoplasm
    • tumor
    • can be benign (cysts) or malignant (invade surrounding normal tissue)
  176. Metastacize
    when malignant (cells that spread to surrounding normal tissue) spread to other tissues/organs of the body
  177. Viruses and cancer
    first virus linked to cancer is RSV (rous sarcoma virus) which caused cancer in chickens
  178. Human Cancers caused by viruses
    • 15% of human cancers are caused by known viruses
    • Epstein-Barr Virus (EBV): Burkitt's lymphoms
    • HPV: cervical cancer
    • Hep B: 80% of liver cancer
    • HSV-8: Kaposi's sarcoma
  179. How many times will normal cells divide in culture
    • 70
    • senescence- deterioration with age
  180. how can viruses "transform" cells
    • can make them divide indefinietly
    • make them not affected by contact inhibition (stopping growing once they touch)
    • do not remain stuck to eachother or culture dish
    • make them need less nutrients and growth factors in media
    • make them exhibit abnormal chromosome numbers
  181. polyploidy
    • aka aneuploidy
    • abnormal chromosome numbers
  182. Viral integration
    when a virus integrates or sneaks its DNA into the host genome, mutations are made in the host DNA
  183. What mutations can be made in host DNA from viral integration
    • the mutations can be in
    • 1. tumor suppressors: usually DNA repair enzymes (BRCA1); when its time to stop cell division, tumor suppressors start normally
    • 2. oncogenes: usually proliferative genes
  184. normal vs mutated proliferative genes
    • normal: proto-oncogene
    • mutated by viral insertions/deletions: oncogene
  185. Disinfectants
    • applied to non living objects
    • decreases the number of microorganisms, but does not sterilize
    • some slow growth while others kill
  186. Antiseptics
    • applied to living tissue 
    • ie neosporin
  187. Sterilization
    • killing or removal of all microorganisms in a material or on an object
    • done by using an autoclave
  188. Sterile
    NO living organisms or endospores are present
  189. Disinfection
    reducing the number of pathogenic organisms
  190. Bacteriostatic
    prevents microorganisms from growing or slows their growth
  191. Bactericide
    kills bacteria
  192. Fungicide
    kills fungus
  193. Germicide
    kills many microbes but usually not spores
  194. Sporocide
    kills endospores and fungal spores
  195. Viricide
    incapacitates viruses
  196. Three principles of sterilization
    • 1. A definite proportion of organisms will die in a given time interval
    • 2. The fewer organisms present, the shorter the time needed to achieve sterility
    • 3. Microorganisms differ in their susceptibility to antimicrobial agents (some sterilization techniques kill quickly, others slower due to resistance, etc- this is true for dissinfectants too)
  197. Chemical Antimicrobial Agents
    • effectiveness is increased by high temperatures
    • effectiveness can be affected by concentration of chemical, pH and time left on microorganisms
    • ethyl and isopropyl alcohols work best at 70% solutions because water is necessary to denauture bacterial proteins (and 100% can burn our lungs if inhaled)
  198. How are chemical agents tested
    • Phenol Test
    • Filter Paper Test
    • Use-Dilution Test
  199. Phenol test
    • phenol- a carboxylic acid
    • a measure of the bactericidal activity of a chemical compound in relation to phenol
    • phenol has a coefficient of 1.0
    • The dissinfectant to be tested is tested along side phenol on a standard microbe (ie salmonella)
    • Dissinfectants more effective than phenol have a coefficient greater than 1, less effective dissinfectants have a coefficient less than one, and equally effective have a coefficient of 1
    • there are different phenol coefficients for each organism
  200. Filter paper test
    • tiny filter paper disks soaked in chemical agent are put on agar plates with a bacterial lawn
    • clear regions around the disks mean they killed local bacterial cells
  201. Use-dilution test
    • A metal tube is coated in bacteria and then dipped into different dilutions of chemical agents
    • finally, the tube is put into growth media to see if bacteria from any of the tested dilutions grow
  202. What are the 6 things we look for in a good dissinfectant
    • 1.Fast acting  (you don't want something that has to sit a while)
    • 2. Effective against all types of infectious agents without destroying human tissue or acting as a poison (so it will get viruses/bacteria etc)
    • 3. Penetrate material easily without damaging it or us
    • 4. Easy to prepare and stable in a number of environmental conditions (dont want it to degrade after a month)
    • 5. Inexpensive and easy to use
    • 6. Smell pretty
  203. How do chemical reagents work?
    • 1. They denature proteins (3D tertiary structure is destroyed)- can be bacteriostatic or bactericidal
    • 2. They can affect membranes- break down the lipids
    • 3. They can affect nucleic acids (DNA/RNA and how they replicate) or energy production (if microbes can't metabolize they'll die)
  204. Detergents
    • contain alkali and sodium
    • kills streptococcus, micrococcus, Neisseria and the flu virus
    • can be cationic + or anionic-
  205. cationic vs anionic detergents
    • anionic are less effective against bacteria because of the - charge of the bacterial cell wall
    • some cationic detergents are quaternary ammonium compounds which contain four organic groups surrounding a nitrogen atom
  206. How do detergents work
    • They trap particles so they can be washed away
    • soaps have hydrophobic heads and hydrophillic tails
    • soap surrounds particle (dirt, microbe, etc)by creating micelles
    • micelles: the hydrophobic parts surround the particle and the hydrophillic tails face outward, this way when you wash with water it will wash the whole micelle including the particle away
  207. What are other things that inhibit microbial growth (9)
    • acids and bases
    • heavy metals
    • halogens
    • alcohols
    • phenols
    • oxidizing agents
    • alkylating agents
    • dyes
    • miscellaneous
  208. Acids and bases inhibiting microbial growth
    • lactic acid and propionic acids are used as food preservatives- add to food to slow bacterial growth
    • vinegar- low pH, can be used to clean
  209. Heavy metals inhibiting microbial growth
    • silver, mercury, selenium
    • not ideal because these are also harmful to us
  210. halogens inhibiting microbial growth
    • chlorine, iodine, bromine
    • salts
  211. Alcohols inhibiting microbial growth
    • denature proteins, dissolve lipids, cell membranes
    • do not sterilize
  212. Oxidizing agents inhibiting microbial growth
    hydrogen peroxide- disrupts disulfide bonds in proteins, changing the conformation and therefore stopping function
  213. Alkylating Agents inhibiting microbial growth
    • disrupt proteins and nucleic acids (but also can disrupt ours)
    • can cause cancer
    • formaldehyde, etc
  214. Dyes inhibiting microbial growth
    • Acridine orange stops cell replication
    • Methylene blue stops bacterial growth
    • Crystal violet blocks cell wall synthesis and inhibits gram + growth
  215. Miscellaneous inhibiting microbial growth
    • plant oils
    • nitrites
    • tea tree oil, natural things can be effective
    • antibiotics come from living organisms (ie fungus)
  216. Physical ways to control microbial growth
    • Heat (most important one)
    • Refrigeration
    • Freezing
    • Drying
    • Radiation
    • Filtration
    • Osmotic pressure
  217. Thermal death point
    the temperature that kills all bacteria in a 24 hour old broth culture at neutral pH in 10minutes
  218. Thermal Death time
    time required to kill all bacteria in a culture at a particular temperature
  219. Decimal Reduction Time
    • time required to kill 90% of organisms at a particular temperature
    • ex: D150C= 30 min
  220. Ways that heat kills microbes
    • Dry heat
    • Moist heat
    • Pasteurization
  221. Dry Heat
    • big ovens
    • slow to penetrate, used for metal instruments, glassware, oils and powders (powders would get wet with moist heat)
    • used if you cant use moist heat due to ie rusting
    • some things can't be dry heated or they will catch fire
    • 171C for 1 hr, 160C for 2hrs, or 121C for 16hrs
  222. Moist Heat
    • autoclave- heats under pressure
    • Maintains temperature and pressure for a period of time
    • Validation includes tapes and documentation
    • 121C and 15lb/in^2
  223. Pasteurization
    • Does not sterilize, but will reduce microbes
    • 71.6C for 15 seconds (flash method)
    • 62.9C for 30 minutes (holding method)
    • ultra pasteurized gets rid of even more bugs, this is why heavy cream expires later than milk
  224. how does an autoclave work
    • uses steam, temp, and pressure 
    • needs to be calibrated and tested often
  225. Describe how an autoclave is tested to see if it is killing microbes
    • buy ampules with a glass container inside that holds media, and on the bottom (not in the media) is a spore strip
    • put this through an autoclave run, the pressure will break the inner glass tube and the media will come out and cover the spore strip
    • after the run, incubate the tube, if the medium remains clear, it works, if it is cloudy, growth occurred meaning the autoclave did not do its job and sterilize
  226. Refrigeration
    4-5C, slows microbial growth
  227. Freezing
    • -20C preserves food for longer periods of time
    • Microbes can be frozen at -80C or in liquid nitrogen at -180C
  228. Drying
    • Absence of water inhibits microbial enzymes
    • Endospore-forming bacteria will survive drying
  229. Freeze-drying
    • lyophilization: dried after being frozen
    • used for long term preservation of microbes
  230. Radiation types
    • Ultraviolet light
    • Ionizing Radiation
    • Microwave radiation
    • Strong visable light
  231. Ultraviolet Radiation
    • 40-390nm but 200nm is most effective against microbes as it damages proteins
    • UV light is absorbed by nucleic acids which damages them but they can use repair enzymes
    • useful for destroying viruses
    • does not penetrate well, but useful for decontaminating air
  232. Ionizing radiation
    • Xrays (0.1-40nm) and gamma rays create ions in substances by dislodging electrons
    • useful for killing bacteria and viruses in foods
  233. Microwave radiation
    • 1mm-1m
    • only useful for sterilizing substances that contain water
  234. Strong visable light
    • 400-700nm can oxidize certain bacterial enzymes
    • certain dyes can increase the effect of strong light on microbes
  235. Filtration
    • passing material through a strainer to rid it of microbes
    • good for small quanitities, but can be expensive
    • membrane filters have varying pore sizes that let organisms of different sizes pass throught
    • used when heat sterilization would harm the substance
    • 0.025um-25um
    • 0.2micron filters are commonly used to sterilize cultures from bacteria
    • HEPA filters have an average pore size of 0.3um and are used to filter air
  236. Osmotic pressure
    • high concentrations of sugar and salt can cause plasmolysis (loss of water)
    • this leads to bacterial cell death
    • used in jellies, salted meats
  237. chemotherapy
    generic term- any chemical agent used to treat any aspect of a disease
  238. antimicrobial therapy
    chemical agents used to treat diseases caused by microbes
  239. antibiotic
    • chemical substance produced by microorganisms which has the capacity to inhibit the growth of bacteria
    • ie molds produce pennecillin
  240. synthetic drugs
    chemical agents produced in a laboratory
  241. semisynthetic drugs
    • chemical precursor is made in a laboratory and given to a microorganism to complete synthesis
    • the microorganism finishes the job and then scientists harvest the product from the microbes
  242. what two terms are used interchangably
    antimicrobial therapy and antibiotics
  243. What are antibiotics designed to have
    selective toxicity
  244. Selective toxicity
    • a substance that has selective toxicity will harm microbes without significantly damaging host cells
    • depends on dose, exposure and metabolism
    • If an antimicrobial agent is too toxic to take systematically, it can only be used topically, or on the skin
    • anything taken internally must have selective toxicity
  245. Drug range
    Drugs have variable ranges between the therapeutic dosage level (where the drug does what its supposed to do) and the toxic dosage level (where it starts to affect you)
  246. Chemotherapeutic index
    • every drug has one
    • it is the maximum tolerable dose per kg of body weight divided by the minimum dose per kg body weight that will cure the disease
  247. What is a nontoxic substance
    • everything is toxic, it just depends on the dose, exposure and metabolism of the thing 
    • just because something is natural doesn't mean it's non toxic
  248. Example of dose, exposure and metabolism with a drug
    • ie alcohol
    • Exposure: you can sit in a bathtub of vodka and be fine. You need to ingest it for the exposure
    • Dose: 1 drink is not toxic wheras 15 drinks is
    • Metabolism: 2 drinks in 45min overwhelms the metabolism and it cant keep up which is why you begin to feel those toxic effects
  249. Spectrum of antibiotic activity
    • a good antibiotic will target a broad spectrum of microbes
    • ie: tetracycline targets gram + gram- clamydias and rickettsias while isoniazids only target mycobacteria and are specific
    • use a broad spectrum of abx if you are not sure what is causing the infection to cover all your bases, bc different abx kill in different ways
  250. Antibiotic modes of action
    • they target diff parts of the bacterial cell depending on which abx you use
    • inhibit cell wall synthesis
    • disrupts cell membrane function
    • inhibition of protein synthesis
    • inhibition of nucleic acid synthesis
    • antimetabolites
  251. abx inhibiting cell wall synthesis
    • penicillin, cephalosporin, ammoxicillin
    • contain beta-lactam rings that prevent bacterial enzymes from crosslinking peptidoglycan (gets in the way of the framework making peptidoglycan- fence like structure has holes in it)
    • doesn't affect eukaryotic cells (no cell wall) or cells without peptidoglycan
  252. abx disrupting cell membrane function
    • polymyxins: work on bacteria, especially gram -
    • polyenes: work on fungal cells
  253. abx inhibiting protein synthesis
    • aminoglycoside antibiotics (streptomycin, chloramphenicol, erythromycin, tobramycin)
    • target the translation part of protein synthesis
    • work on 70s ribosomes
  254. abx inhibiting nucleic acid synthesis
    ie- rifamycin binds to bacterial RNA polymerase
  255. Abx as antimetabolites
    • competitive inhibitors of enzymes (sulfa drugs and paraaminobenzoic acid (PABA) ie sulfonilmide, trimethoprim
    • enzymes are very specific for substrates and these antimetabolites bind to the active site on the enzyme so it cant bind the substrate
    • some, esp antiviral drugs, will act like molecules and mimic things- mimic receptor protein on the cell that virus binds to therefore tying the virus up so their bound to these drugs rather than the cell receptor
    • some can "squeeze" into normal chemical structures (ie the mimicry)
  256. Side effects of abx
    • toxicity
    • allergy
    • disruption of microflora
    • resistance of microbes
  257. toxicity side effect of abx
    • can be really strong (ie TB drugs)
    • can affect normal host tissues, particularly the liver (the detox station that breaks these things down)
  258. allergy side effect of abx
    • host immune system overreacts and treats the drug as foreign
    • ie a penicillin allergy- recent study found many people thought they were allergic to penecillin but it was just the side effects
  259. Disruption of microflora side effect of abx
    • antibiotics get rid of bad bacteria but also commensal bacteria, throwing off the balance
    • other microbes can take over where good ones were killed off (called a superinfection) ie c. difficile
  260. How does resistance to abx arise
    • a microbe that USED to be susceptable to an antibiotic is no longer affected by it- something has happened to make it resistant
    • can be acquired through genetic changes (spontaneous mutation or uptake of plasmids during conjugation or transduction)
    • some bacteria can change to "L form" and stop making a cell wall for a couple of generations which increases resistance against cell wall specific abx (won't affect them)
    • can also evade abx by "hiding" in tissues (such as TB in the lung)- hides from the immune system
  261. Bacterial mechanisms of resistance (5)
    • Alteration of targets
    • Alteration of membrane permeability
    • Development of enzymes 
    • Alteration of an enzyme
    • Alteration of a metabolic pathway
  262. Alteration of targets
    • mutation in DNA changes a protein so that an antibiotic can no longer bind to it
    • if we have an abx that targets a certain protein on the microbe, if theres a mutation that changes protein shape, the abx wont bind
  263. Alteration of membrane permeability
    mutation in DNA changes membrane proteins so that an antibiotic can no longer penetrate into the cell
  264. Development of enzymes
    • A new enzyme can break down an antibiotic
    • ie- B-lactamase breaks down B-lactam rings of some antibiotics therefore maintaining the cell wall structure and the bacteria will live
  265. Alteration of an enzyme
    • causes competitive inhibitors not to work
    • an enzyme can change in some way to function even in the presence of a competitive inhibitor
  266. Alteration of metabolic pathway
    • bacteria can bypass a metabolic pathway or a step in a metabolic pathway inhibited by an antibiotic
    • ie: a bacteria converts substrate A to B to C to D and an antibiotic inhibits the conversion from A to B, the bacteria can find a way to convert A to C directly therefore bypassing that step and the antibiotic will have no effect
  267. How can we limit drug resistance
    • 1. Use high enough dose for long enough period of time to kill ALL pathogens and their mutants
    • 2. Use 2 antibiotics- synergism (additive effect)- ie penicillin inhibits cell walls and therefore allows more streptomycin to penetrate the cell
    • 3. Restrict antibiotics only for essential use-not prescribed for viruses, can knock out good bacteria for no reason if not needed
  268. Augmentin
    • an example of an additive effect by synergism
    • ammoxicillin with clavulanic acid
    • clavulanic acid that binds b-lactamase and keeps it from inactivating amoxicillin
  269. Why should you finish your abx full prescription (in words but know the graph too)
    • When there are no antibiotics, you have a small population of highly susceptable organisms, a small population of highly resistant organisms, and the largest population of intermediate organisms (bacterial curve)
    • When you start taking abx by day 3 you have knocked down the highly sensitive population, making a dent in the intermediate population, but you still have the highly resistant group
    • By day 6, you are begining to feel better, your own immune system is stronger and beginning to kick in, the highly sup. pop is basically wiped out, as is most of the intermediate population, and you begin to make a dent in the highly resistant population
    • by day 10, all are wiped out with the abx in combo with your immune system
    • IF YOU STOP AT DAY 6 WHEN YOU FEEL BETTER: the resistant population is not yet wiped out and will take off replicating to replace the niche of wiped out organisms, making you ill again with more resistant bacteria, this type can also spread to other hosts
  270. How do we test microbes for sensitivity to antimicrobial agents
    • Disk diffusion
    • Dilution method
    • Serum killing power
    • Automated methods
  271. Disk diffusion method
    • Kirby Bauer Method
    • very similar to filter paper disinfectant test, except instead its coated with different concentrations of abx
    • filter paper disks with different concentrations of abx put on a lawn of a known microbe
    • clear areas around the disk indicate susceptability
  272. Dilution method
    • organism inoculated into broth in culture dish with many wells
    • decreasing concentrations of antimicrobial agent added to wells
  273. serum killing power
    • helps to find a therapeutic dose
    • uses blood from a patient recieving antimicrobial therapy and inthe lab microbe is added and theyll see if it grows
    • is it concentrated enough in the blood to kill this bacteria
  274. Automated methods
    • trays with tiny wells support growth of a variety of microbes
    • antimicrobial agents can be added and growth of the microbes is tested by a machine and analyzed by a computer
  275. Zone of inhibition
    • the distance of cleared area around the filter paper in the disk diffusion method
    • can be measured and a chart can tell you if a microbe is susceptable, intermediate or resistant
  276. What is the ideal antimicrobial agent
    • 1. Soluble 
    • 2. Selective toxicity
    • 3. Toxicity not altered by food, other drugs, diseases in host (ie you don't have to take it on an empty stomach)
    • 4. Doesnt cause allergies
    • 5. Stable over many hours
    • 6. Few strains are resistant to it
    • 7. Long shelf life
    • 8. Cost-effective
    • 9. Patient compliance (patient needs to do what they're supposed to (ie kids taking medicine- wont bc it tastes bad, not complying)
Card Set
Microbiology Exam 2
Test of 7/12/18