Micro Lecture Exam II (part 2)

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Micro Lecture Exam II (part 2)
2014-02-21 00:22:57

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  1. Genotype
    • organism's DNA (collection of genes)
    • represents that organism's potential properties
    • (soem properties are there, but are not developed or expressed)
  2. Chromosome
    neatly packaged DNA molecule
  3. Chromosome of a Prokaryote
    • the chromosome is referred to as the nucleoid
    • DNA is not bund with histone proteins
  4. Bacterial Chromosome
    • most contain a circular DNA
    • not wound around histone proteins to form nucleosomes
    • few thousand unique genes
    • structural gene sequences make up the largest part of bacterial DNA
    • one origin of replication to initiate DNA replication
  5. The Gene
    • unit of heredity
    • segments of DNA that code to make a particular protein or functional product
  6. Process of making proteins begins with...
  7. Transcription
    • process of making proteins
    • begins with transcription
    • happens-->1.  RNA is copied from DNA
  8. 2 step
    2. mRNA will carry the coded info or instr for assembling the polypeptides from DNA to the ribosomes where the polypeptides will be made
  9. building of polypeptides is called....
  10. Translation
    • actual building of polypeptides
    • deciphering of nucleic acid info and converting that info into a language cell can understand
  11. replication transcription translation diagram
  12. Operon Model
    how transcription of mRNA is regulated
  13. Repression
    • inhibits gene expression and decreases the synthesis of enzymes
    • 1. Repressors
  14. Repressors
    • proteins
    • stop the ability of RNA polymerase to initiate transcription from repressed genes
  15. Induction
    • activates transcription by
    • producing an inducer (chemical that induces transcription)
  16. Operon
    • functional unit
    • include:
    • 1. Structural genes
    • 2. Regulatory genes
    • 3. Control genes
  17. Regulator
    gene that codes for a protein capable of repressing the operon (a repressor)
  18. Control locus
    • (promoter and operator)
    • sequence where transcription of the structural genes is initiated
  19. Structural locus
    • three genes
    • each coding for a diff enzyme need to catabolize a substance
    • catabolize (make a substance undergo catabolism)
  20. Example of The Operon Model
    • ex: Lactose
    • when lactose is present, E. Coli synthesizes enzymes needed to break down lactose
    • Lactose is an inducer molecule
  21. If lactose is absent (The Operon Model)
    a regulator gene produces a repressor molecule that binds to a control region called the operator site, preventing the structural genes from encoding the enzyme for lactose digestion
  22. If Lactose is present (The Operon Model)
    • it bidns to the repressor at the operator site
    • structural genes are released and produce their lactose digesting enzymes
  23. Genes and enzymes
    • genes contain instr for enzymes
    • if inducer molecules are present
    • bacteria are able to express their genes if this particular nutrient is in the environment
  24. Transformation (gene 2008)
  25. Mutation (def.)
    permanent change in the DNA sequence

    (make certain microorg resistant to antibiotics or increase tehir pathogenicity)
  26. Mutation effects
    • 1. some have an expressive effect
    • gene mutates, the enzyme encoded by the gene can become less active or inactive bc the sequence of the enzyme amino acids may have changed
    • 2. can be harmful or fatal change to the cell, or it can be beneficial especially if it creates a new metabolic activity
  27. Types of Mutations
    • 1. Point mutation
    • 2. Missence mutation
    • 3. Nonsense mutation
    • 4. Frame Shift mutation
  28. Mutations diagram
  29. 1. Point Mutation
    • (substitution)
    • substitution for a normal base
    • causing alteration of the genetic code, which then can be replicated
    • most common type of mutation
  30. 2. Missence mutation
    a new amino acid is substituted in the final protein by the mRNA during translation
  31. 3. Nonsense mutation
    • terminator codon in the mRNA appears in the middle of a generic message instead of at the end of the message
    • causes premature termination of protein synthesis
  32. 4. Frame Shift mutation
    nucleotides are either added or inserted into the DNA strand
  33. Mechanisms of DNA transfer
    • 1. Conjugation
    • 2. Transformation
    • 3. Transduction
  34. 1. Conjugation
    • mechanism of DNA transfer
    • plasmid (or other genetic material) is transferred from one bacterium to another throgh a sex pilus
    • can share plasmids that are known as resistance plasmids which bear genes that make bacteria resistant to some antibiotics
  35. Conjugation diagram
  36. 2. Transformation
    • the acceptance of small fragments of DNA from the surrounding environment by a bacterial cell
    • facilitated by competent cells

    bacteria can acquire genes for structural components like capsules and fimbriae; or for antibiotic resistance
  37. mouse experiment
  38. 3. Transduction
    • process by which a bacteriophage serves as a carrier for the transfer of DNA from one bacterium to another
    • occurs generally only among bacteria of the same species

    • Virulent strains of C. diphtheriae, Clostridium and Streptococcus pyogenes acquire their ability to produce toxins through transduction
  39. Table of Intermicrobial Exchange
  40. Sterilization
    • destruction of ALL microorganisms, viruses, and endospores
    • used in cultured media and prepared food
    • performed by:
    • 1. Autoclave
    • 2. Incineration
    • 3. Sterilizing gas (ethylene oxide)
  41. Autoclave Sterilization
    • cylindrical metal container that has a metal tight door to hold one end with racks to holds materials
    • complex network of valves
    • temperature and pressure gauges
    • duct for regulating and measuring  pressure and conducting steam into the chamber
    • best results is at 15 PSI at 121 temp
    • superior choice to sterilize heat resistant mareial such as:
    • glassware, cloth, rubber, gloves, metallic equipment, liquids, paper and some heat resistant plastic
    • NOT: substances that repel water (wax, oils, powders)
  42. 2. Incineration
    • 1. flame of electric heating coil
    • 2. Bunsen burners 1870oC
    • 3. Incinerators 800-6500oC

    • hospital & research labs
    • destruction of infectious substances, animal carcasses, and pathology samples
  43. 3. Sterilizing Gases (Ethylene Oxide)
    • chemiclaves are automatic ethylene oxide sterilizers
    • has gas canisters containing ethylene oxide
    • Ethylene's oxide effective insterilizing surgical devices, syringes, and disposable Petri plates
  44. gases
    • Glutaraldehyde- a sterilant for materials usually damaged by heat-respiratory therapy equipment, fiber optic endoscopes, kidney dialysis equipment, alternative vaccine preservative, sanitizer for poultry carcasses.
    • Ethylene Oxide-heat sensitive plastics and  delicate instruments  in hospitals and industries Chlorine dioxide –air and surface sterilant
  45. Ionizing Radiation
    • •Ionizing radiation can penetrate a solid barrier,  enter it,  and dislodge electrons from it. Breakage of DNA creates massive mutations
    • •Completed by gamma rays, X rays, and cathode rays
    • •Ionizing radiation can be used on  flour, meats, fruits and vegetables
  46. UV Radiation (Disinfection, not Sterilization)
    • UV radiation (nonionizing) excites atoms by raising them to a higher energy state, but does not ionize the. Pyrimidine dimers are formed instead
    • Nonionizing radiation can be used for disinfection, but not sterilization
  47. Antisepsis
    • rediction of pathogenic microoragnisms and viruses on living rissue
    • any practice that prevents the entry of infectious agents into sterile tissues preventing infection
    • Treatment: chemical antimicrobials (iodine, alcohol)
    • ex: handwashing, flame sterilization of equipment, and preparing surgical equipment and instruments 
  48. Aseptic (def.)
    free of pathogenic contaminants

    ex: proper hand washing, flame sterilization equip etc
  49. Sepsis (def.)
    growth of microorganisms or the presence of microbial toxins in the body, blood, and other tissues
  50. Disinfection (def.)
    • destruction or killing of microorganisms and viruses on nonliving tissue by the use of chemical or physical agents
    • destroy vegetative forms of pathogens not endospores
    • ex: phenols, alcohols, aldehydes, and surfactants
  51. Halogens
    • non mettalic, highly chemical elements which are effective against vegetative cells, fungal cells, fungal spores, protozoan cysts, and many viruses
    • inhibit protein function
    • ex: Iodine- surgery, campers to disinfect water
  52. Degermination (def.)
    • removal of microorganisms by mechanical means
    • ex: cleaning the site of an injection
    • using an alcohol wipe
  53. Pasteurization (def.)
    uses heat to kill pathogens and reduce the number of food spoilage microorganisms in food and beverages
  54. Sanitation (def)
    treatment to remove or lower microbial counts on objects such as eating and drinking utensils to meet public health standards
  55. cide or cidal (def)
    death or destruction of an organism

    • ex: bacteriocides, fungicides, germicides
    • bactericide- agent destroys bacteria but not endospores
  56. static or statis (def.)
    inhibition of growth

    • ex: refrigeration, freezing, dissection, and some chemicals
    • Bacteriostatic- agent that prevents stops, or inhibits the growth of bacteria
  57. Iodine
    antiseptic prep for surgery and injection, surgical hand scrubs and water treatment
  58. Phenol
    • strongly microbiocidal and destroy vegetative bacterial, fungi, and viruses
    • ex: Lysol spray, Triclosan in soaps cosmetics and medications