Micro Exam 1

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Micro Exam 1
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2010-09-06 02:16:16
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Svinth Micro Exam
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Micro SRJC Svinth
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  1. Atoms: smallest unit of matter
    • Nucleus contains:
    • Protons (+1) charge; number of protons determines which atom
    • Neutrons (no charge) add weight to nucleus
    • Electrons (-1) orbit the nucleus; only part involved in chemical reactions
  2. Electrons orbit atom
    • 1st orbital filled when it contains 2 electrons
    • 2nd orbital filled when it contains 8 electrons
    • Atoms are stable when their orbitals are filled
    • When their orbitals are not filled, atoms are reactive
  3. Chemical Bonds
    • Atoms can fill their orbitals by sharing electrons with another atom
    • A shared electron pair is called a covalent bond
    • When 2 or more atoms are bonded together, a molecule is created
  4. Cohesion
    Water sticks to itself
  5. Adhesion
    Water sticks to other polar substances
  6. Water as Solvent
    Water is a good solvent for polar substances
  7. Water with Nonpolar substances
    • Water will not dissolve nonpolar substances
    • There are no charges to attract water
  8. Carbon-Based Life Forms
    • Cells are roughly 70% water
    • Dry weight of cell is mainly Carbon
    • Carbon is NOT a major constituent of the earth
    • It is life’s building block because of its unique structure
  9. Carbon Structure
    • C can make up to 4 highly stable covalent bonds
    • C can make single, double, or triple bonds
    • C can make long stable chains with itself
    • C also binds to life’s other elements (H, O, N, S, Phosphate)
  10. C bonds to other life elements
    • These bonds are polar
    • These bonds are not as stable as C-C or C-H bonds
    • These bonds are thus reactive
    • Life is not inert!
  11. Carbon Compounds
    • There are 4 classes of C cmpds that compose living things
    • Carbohydrates
    • Lipids
    • Proteins
    • Nucleic acids
  12. Carbohydrates
    • Building block is glucose (sugar)
    • Formed by dehydration reactions
    • Two together create disaccharides
  13. Polysaccharides
    • Long chains of sugars are called polysaccharides
    • Function as energy storage or structure
    • Examples include:
    • Starchstorage
    • Chitinstructure
  14. Lipids
    • Building block is often glycerol
    • To which Fatty Acid chains are attached
    • Formed by dehydration synthesis
  15. Lipids: Function
    • Lipids are important as:
    • Energy storage:
    • Insulation:
    • Thermal:
    • Electrical:
    • Building blocks of membranes
    • Building block of steroids
    • Fat-soluble vitamins (A, D, E, K)
  16. Lipids: Structure
    • Many lipids usually found as Fatty Acids (16-18 Cs)
    • Lipids are either saturated or unsaturated
    • Saturated refers to having as many Hs bonded to the Cs as possible
    • Unsaturated have double bonds between Cs
  17. Phospholipids
    • Phospholipids
    • 2 fatty acid chains and a phosphate head
    • Amphipathic
    • Building block of membranes
  18. Phospholipids form Membranes
    • Phospholipids form bilayers
    • Degree of unsaturation determines membrane fluidity
  19. Steroids are based on Cholesterol
    • Cholesterol is a lipid
    • Highly hydrophobic
    • Building block of steroid hormones
  20. Proteins: Workhorses of the Cell
    • Anything that happens in the cell is due to protein
    • Proteins function:
    • Structure
    • Transport
    • Protection/Defense
    • Control/regulation
    • Catalysis
    • Movement
    • Storage
  21. Levels of Protein Structure
    • Primary Structure: “spelling” ; actual amino acids present, the polypeptide chain
    • Secondary structure: local folding pattern; α helix, β sheet, turns
    • Tertiary structure: overall 3D fold; usually a mixture of secondary structure
    • Quaternary structure: 2 or more protein subunits come together to make one protein
    • Primary Structure determines Tertiary Structure
  22. Primary Structure
    Actual amino acids present
  23. Nucleic Acids
    • Two classes:
    • DNA
    • RNA
  24. What is Microbiology?
    • Study of microorganisms
    • Organisms too small to be seen by the naked eye
    • Diameter of 1 mm or less
  25. Ecological Roles of Microorganisms
    • Pathogens
    • Primary producers
    • Decomposers
    • Nutrient cycling
    • symbionts
  26. Economical Roles of Microorganisms
    • Chemical synthesis
    • Fermentation
    • Proteins (e.g. insulin)
  27. Discovery of Microorganisms
    • Robert Hooke (1665)
    • Simple microscope; much like a magnifying glass
    • Observed cork
    • “little boxes” (cells)
    • Later, saw cells with a double lens microscope
    • Beginning of Cell Theory
  28. Antoni van Leeuwenhoek
    • Discovered:
    • Early embryos of plants
    • Small invertebrate animals
    • Spermatozoa
    • Red blood cells
    • Capillary circulation
    • Microorganisms
  29. Biogenesis vs Spontaneous Generation
    • Belief that life arises from non-life
    • Taken as doctrine until 1665
  30. Francesco Redi (~1670)
    • Observation: meat left out uncovered produces maggots
    • Hypothesis: Flies lay eggs on the meat that hatch into maggots
  31. Spallanzani (1740s)
    • Hypothesis: microorganisms are the same as any other organism and only come from reproduction of previously existing microorganisms
    • Prediction; if broth is boiled to sterilize it and then not exposed to air, microorganisms cannot enter and the broth will remain sterile
  32. Spontaneous generation put to rest by Louis Pasteur
    Observation: air drawn through cotton leaves a dust deposit that contains microorganisms

    Hypothesis: microbes enter broth as dust particles in the air

    Prediction: IF air is allowed to enter sterile broth, but dust is not, THEN nothing will grow in the broth
  33. Jospeh Lister
    pioneered use of carbolic acid spray in the OR
  34. 1847 – ignaz Semmelweis
    pioneered handwashing in obstetrics
  35. pasteurization
    Reduction of food spoilage organisms by heating
  36. Koch’s Postulates
    a process to determine the etiology (cause) of an infectious disease
  37. Koch's Postulates
    • 1. The suspected pathogen must be found in all cases of the disease, but not in healthy individuals
    • 2. The suspected pathogen must be isolated from a diseased host and grown in pure culture
    • 3. The pure culture must produce the same symptoms when inoculated into a healthy host
    • 4. The same pathogen must be isolated from the secondary host
    • 5. Identical microorganisms are identified.
  38. Exceptions to Koch’s Postulates
    • 1. Some pathogens cannot be grown in pure culture
    • Unknown culture
    • requirements
    • 2. Many pathogens are species-specific: there may be no animal models for a human disease
    • 3. Some pathogens can persist
    • in “carriers” who have no symptoms
    • 4. Some microorganisms can cause more than one disease
    • 5. Some diseases (sets of symptoms) have more than one cause
  39. Medical Microbiology
    • 1. Identify the causative agent (Koch’s Postulates)
    • 2. Cure or prevent the disease
  40. Early Vaccination
    • Lady Mary Montagu
    • “inoculation parties”
    • “customers” would have a scratch made on a limb
    • Pus from the victim of a mild attack of smallpox would be smeared on open vein of customer
    • Worked most of the time
  41. Edward Jenner
    Jenner 1798. Cowpox pustule material protects humans from small pox
  42. Pasteur 1885 - Rabies vaccination
    Basic idea: pre-exposure to weakened pathogen later protects from the active pathogen.
  43. Discovery of Viruses
    • Pasteur & Koch knew:
    • Pathogens exist that are too small to see with a light microscope and pass through filters that trap bacteria (contagious fluid)
    • These pathogens cannot be grown in lab on nutrient medium
    • Example: the agent that causes rabies
  44. Time Line of Viruses
    ~1950 Viruses are obligate intracellular pathogens – must be grown in live organisms, or in tissue culture

    ~1960 antibodies discovered – specific antibodies can be used to identify specific viruses

    • 1970s onwards. Molecular techniques –
    • DNA, RNA or protein analysis- used to detect presence of viruses
  45. Modification of Koch’s Postulates for use with viruses
    • Postulate 1:
    • Viral particles, viral proteins, viral nucleic acids or antibodies specific to the virus are present in infected individuals and not present in uninfected individuals
    • Postulate 2:
    • Viruses can be grown in tissue culture, or observed in infected tissues under the EM
    • Postulate 3:
    • Cell-free filtrates of infected material produce disease in animal models (if available) or in tissue culture

    • Postulate 4:
    • Viral particles from second host look the same, and have the same molecular characteristics as the original isolate.
  46. In practice with Koch's Postulates
    • If a certain virus is consistently associated with a certain disease AND
    • Methods used to prevent transmission of that virus reduce incidence of the disease OR
    • A vaccine prepared using the virus prevents the disease
    • Then the virus is considered to be the causative agent
  47. Euk. Glycocalyx
    • Simpler than prokaryotic glycocalyx
    • Plants/algae: cellulose
    • Fungi: chitin
    • Yeasts: glucan, mannan

    • Function:
    • Strengthen plasma membrane
    • Cell-cell attachment
    • Cell-cell communication
    • Contact inhibition
  48. Euk. Plasma Membrane
    • Carbohydrates associated
    • Sterols strengthen membrane
    • Transport
    • No group translocation
  49. Euk. Pinocytosis
    • Cell “drinking”
    • Inward folding of plasma membrane brings in extracellular fluids
    • May be a way for cell to recover from exocytosis
  50. Cytoskeleton
    • Function:
    • Shape
    • Transport
  51. Eukaryotic DNA
    • Linear
    • Histones
    • Chromatin
    • Chromosomes
  52. Euk. Cell Division
    Meiosis and Mitosis
  53. Glycocalyx
    • Some bacteria have this
    • Capsule
    • Slime layer
    • Allows bacteria to evade immune responses
    • Virulent
    • E.g. B.anthracis, Streptococcus pneumoniae
  54. Extracellular Polysaccharide
    • Glycocalyx composed only of sugar
    • Allows attachment of bacteria to surfaces
    • Called biofilm
  55. Penicillin
    • Fungal in origin
    • Inhibits enzyme that cross-links amino acids between rows of NAG/NAM
    • Causes cells to burst
  56. Gm+ Teichoic Acid
    • 2 classes
    • Lipoteichoic: spans peptidoglycan layer
    • Wall teichoic: linked to peptidoglycan layer
    • Function: stability, cation transport (?)

    The teichoic acid help keep the peptidoglycan attached to membrane. It also may help to get cations in.
  57. Four basic arrangements of bacterial flagella
    Flagella is usually found in one of four arrangements. Amphitrichous is on both ends. These can move in both directions. Lophotrichous has two on one end and the Peritrichous can be anywhere. This can move very fast because of the flagella
  58. Gm-
    • Thin peptidoglycan layer
    • Outer membrane
    • Periplasmic space
    • This contains transport proteins and degradative enzymes


    Periplasam contains transport proteins.
  59. Gm- Outer Membrane
    • Lipopolysaccharide
    • LPS
    • O polysaccharide (differs)
    • Lipid A (endotoxin)

    Lipid A will cause a lot of problems so you must have antibodies to clean it up. Lipd A can have the same bacteria as the entire cell.
  60. Gm- Outer Membrane
    • Highly (– ) charged
    • Functions:
    • Evades phagocytosis by complement
    • Barrier to antibiotics, digestive enzymes, heavy metals, bile salts, certain dyes

    Every cell is negatively charged on the outside. Complement will bind to blood stream in body Complement helps macrophage find it’s target
  61. Mycobacteria
    • Obligate intracellular
    • Lack cell walls
    • Sterol in plasma membrane

    Has to live inside of cell to survive. Wants to live in macrophage which is the bodys police force. Sterols add stability at high temperature and it prevents things from forming solids in cold temperatures. Causes TB.
  62. Archae
    • No peptidoglycan
    • Psuedomurein
    • No D amino acids
    • No NAM
    • N-acetylosaminuronic acid
  63. Plasma Membrane
    • Phospholipid bilayer
    • Proteins
    • No carbohydrates
    • No sterols
  64. Plasma Membrane
    • Functions:
    • Pump ions
    • ATP Synthesis
    • Protein secretion
    • Lipid synthesis
    • Breakdown of nutrients
    • Transport of materials
    • Pigments
    • Photosynthesis
    • Infolding of plasma membrane: chromatophores
  65. Plasma Membrane-Selectively Permeable
    Diffusion is based on size and concentration gradient. Water gets in but it is much slower. Non polar gets it. There is no energy required for facilitate diffusion. It is facilitated by the concentration gradient. Active transport is when you need something to get across that the membrane doesn’t like. Requires energy to do that. Group adds a phosphate to slap a charge on it so it cant just slip by. This is a way for the cell to accumulate things on the inside. Sometimes it does require ATP but sometimes it doesn’t.
  66. Cytoplasm
    • ~80% H2O
    • Proteins
    • Carbohydrates
    • Lipids
    • Inorganic ions
    • Low MW cmpds
  67. Ribosomes
    • Many antibiotics work by inhibiting protein synthesis
    • Work only on 70S ribosomes
    • Ineffective on euk ribosomes
    • 30S: streptomycin, gentamicin
    • 50S: erythromycin, chlroamphenicol
  68. Inclusions
    • Concentrate reserve deposits
    • May relieve osmotic pressure
    • Include:
    • Gas vacuoles
    • Carboxysomes
    • Metachromatic
    • Polysaccharides
    • Lipid inclusions
    • Sulfur granules
    • magenetosome
  69. Formation of Endospores
    • Some of the most virulent. Requires a lot of energy.
    • Endosperm is a resting body. 1. Copy your DNA. 2. Separating out a small section that contains DNA. 3. Complete separate membrane within the larger membrane. 4. Peptidoglycan starts to form and it starts to dry out. 5. Enzymes break down DNA. Endospores are very resistant to high heat, UV light. Allows bacteria to sit and wait to germinate.
  70. Spore Germination
    • Changes to endospore coat
    • Physical or chemical
    • Enzymes within spore break down outer layers
    • H2O gets in
    • Metabolism begins

    Vegetative cell is one that is actively growing. Resting state is an endospore. To get to a vegetative cell it must germinate.
  71. How to deal with endospores?
    Heating cycles

    Heat the spore up and then lower the temperature and wait (big component). It then germinates and it is a regular bacteria that you can boil and kill. It does not kill the spore but it kills the vegetative cell.
  72. Cell Theory
    • There are 3 tenets to Cell Theory
    • 1. The cell is the smallest unit of life
    • 2. All living things are composed of one or more cells
    • 3. All cells come from cells
  73. The Unity of Life
  74. All cells share certain basic characteristics of structure and function
  75. Common Cell Structures
    • Plasma membrane - lipid bilayer
    • DNA - double stranded
    • Ribosomes - site of protein synthesis
    • Cytoplasm - interior of cell
  76. Unity of Life
    • All cells are composed of the same basic elements
    • C, H, O, N, S, P
  77. Unity of Life
    • All cells are composed of the 4 carbon compounds:
    • Carbohydrates
    • Lipids
    • Proteins
    • Nucleic acids

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