CONCEPTS CHAP 6

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sandovalfj
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CONCEPTS CHAP 6
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2013-03-04 16:52:04
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CONCEPTS
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  1. WHATS THE DIFFERENCE BETWEEN MACRO AND MICRO NUTRIENTS
    • Macronutrients- required in relatively large quantities and play principal roles in cell structure and metabolism. ie- carbon, hydrogen and oxygen. 
    • Micronutrients (trace elements)- magnesium, zinc and nickel are present in smaller amounts and involved in enzyme function and maintenance protein structure
  2. Understand that bacteria live in complex associations/ecosystems with many other organisms.
    • In all but the rarest instances, microbes live in shared habitats- gives rise to complex and fascinating associations. 
    • These interactions can be beneficial or harmful or have no effect.
    • Obligatory or non-obligatory to members. 
    • usually involve nutritional interactions
  3. Process of Bioflim formation
    • 1. "pioneer" colonizer initially attaches to a surface
    • 2. other microbes then attach to those bacteria or polymeric sugar or protein substance secreted by microbial substance secreted by the microbial colonizers
    • 3. attached cells are stimulated to release chemicals as the cell population grows.
  4. Role of Quorum sensing
    • Used by bacteria to interact withmembers of the same species as well as members of other species
    • Structure of bioflims:
    • -cannot be eradicated by traditional methods
    • -partnership among multiple microbial inhabitants
    • -bottom can have different pH and oxygen conditions
    • -large complex communities
  5. Know the role of a bioflim to the survival and colonization of organisms and know the complications they create in the health industry
    • Bacteria use quorum sensing to communicate
    • -eventually they will form a complex community
    • -these communities have different biological characteristics 
    • -these microbes are different from those in a planktonic environment. Different genes are activated in two situations
    • -single bioflim is a partnership among multiple inhabitants thus cannot be eradicated.
    • This synergism has led to necessity of rethinking treament plans
  6. Process of binary Fission
    • 1. Once cell becomes two
    • 2. parent cell enlarges
    • 3. duplicates its chromosomes
    • 4. starts to pull its cell envelope together to the center of the cell
    • 5. cell wall eventually forms a complete central septum.
  7. Budding vs Binary Fussion
    • Binary Fission- the organisms replicates and divides to make two new cells
    • Budding-A new organism is formed from the old. it "buds" off
  8. logarithmic
    2 raised to the exponent
  9. Arithmetic growth
    • plotting the data arithmetically gives a constantly curved slope
    • -log graphs are preferred because an accurate cell number is easer to read, especially during early growth phases.
  10. Be prepared to label the growth curve-
  11. Different methods used to quantify bacterial cells (3)
    • 1. turbidity
    • 2. plate count
    • 3. genetic probing
  12. Turbidity/Turbidometry
    • -Clear nutrient solution becomes cloudy or turbid as microbes grow in it
    • - the greater the turbidity the larger the population size
  13. Counting
    • 1. Direct Cell count- measured microscopically
    • 2. Coulter counter- electronically scans a fluid as it passes through a tiny pipette
    • 3. flow cytometer- works similarly to a coulter counter, but can measure cell size and differentiate between live and dead cells.
  14. Genetic probing
    Uses real time PCR to quanitfy bacteria and other organisms present in the environment or tissue samples
  15. Different feeding strategies (6)
    • 1. photoautotroph
    • 2. chemoautotroph
    • 3. chemoheterotroph
    • 4. photoheterotroph
    • 5. lithoautotroph
    • 6. saprobes
  16. Heterotroph vs autotroph
    Heterotroph- organism obtains carbon in an organic form

    Autotrophic-"self feeder" organism that uses inorganic CO2 as its carbon source- special capacity to convert CO2 into organic compounds- not nutritionally dependent on other living things
  17. Energy source-
    Phototrophs
    Chemotrophs
    Phototrophs- microbes that photosynthesize

    Chemotrophs- gain energy from chemical compounds
  18. Autotrophs (2)
    • Photoautotrophs- photosynthetic can capture energy of light rays and convert it into chemical energy that can be used for cell metabolism. ie algae, plants and some bacteria
    • - make up most of food web

    • Chemoautotrophs- two groups
    • 1. Chemoorganic autotrophs- use organic compounds for energy and inorganic compounds carbon source

    • 2. Lithoautotroph- require neither sunlight nor organic nutrients relying on inorganic minerals
    • -Remove e- from inorganic substrates ie Hydrogen gas, hydrogen sulfide and contribute them to CO2 and hydrogen
  19. Heterotrophs
    • Chemohetrotrophs- derive both carbon and energy from organic compounds- process by respiration or fermentation (release energy in form of ATP)
    • 1. Saprobes- free living microorganisms that feed primarily on organic detrius from dead organisms
    • 2. parasites- derive nutrients from cells or living hosts
  20. Four types of Parasites
    1. Ectoparasites- can live ON the body

    2. Endoparasite- IN organs and tissues

    3. Intracellular parasites- most extreme- WITHIN cell

    4. Obligate parasites- unable to grow outside of outside
  21. Be able to discuss the effects of an isotonic, hypertonic and hypotonic solution on both cells with and without cell walls
    • 1. Isotonic- (Equal)- environment is equal in solute concentration to the cells internal environment
    • without cell wall- diffusion of H2O proceeds at the same rate in both direction there is NO net change in cell volume.
    • - Most stable environment for cells because in osmotic steady state with cell

    • 2. Hypotonic(lower)- solute concentration of the external environment is LOWER than that of the cells internal environment. With cell wall- the cell wall swells the protoplast and pushes it tightly against the wall- wall prevents from bursting. 
    • -pure H2O most hypotonic solution into cells and cells without cell walls swell and burst

    • 3. Hypertonic-(higher)- Out of balance with tonicity of the cell cytoplasm- the environment has higher solute concentration than the cytoplasm. With cell wall- water diffuses out of the cell and shrinks the cell membrane away from the cell wall (plasmolysis)
    • without cell wall- water diffusing out of the cell causes it to shrink and become distorted

    • Hypertonic environment will force H2O to diffuse out of a cell has higher osmotic pressure. 
    • - growth limiting effect of hypertonic solution on microbes is the principle behind using concentrated salt and sugar solutions
  22. Types of Active Transport
    • 1. Carrier Mediated- atoms or molecules are pumped into or out of the cell by specialized receptors 
    • 2. Group translocation- molecule is moved across membrane and simultaneously converted to a metabolically useful substance
    • 3. Bulk Transport- Mass transport of large particles, cells and liquids by engulfment and vesicle formation. Processes generally called endocytosis. Phagocytosis moves solids into cell; pinocytosis moves liquids into cell.
  23. Types of Passive Transport
    1. Simple Diffusion- a fundamental property of atoms and molecules that exist in a state of random motion

    2. Facilitated diffusion- molecule binds to a specific receptor in membrane and is carried to other side. Molecule specific. Goes both directions. Rate of transport os limited by the number of binding sites on transport proteins
  24. Know the three types of endocytosis
    1. Endocytosis- cell encloses the substance in the membrane simultaneously forming a vacuole and engulfing it. 

    2. Phagocytosis- when a cell ingests whole cell or large solid matter by a type of endocytosis. (Think of this as engulfing SOLID)

    3. Pinocytosis- how liquid, such as oil or molecules in solution enter cell (LIQUID)

    4. Receptor Mediated- cells internalize molecules (endocytosis) by the inward budding of plasma membrane vesicles containing proteins with receptor sites specific to the molecules being internalized.
  25. Five Types/Classes of Bacteria based on Temperature
    • 1. Psychrophiles- love the cold
    • 2. Psychrotrophs- cold tolerant
    • 3. Mesophiles- medically significant
    • 4. Thermoduric- heat tolerant
    • 5. Thermophile- Heat loving
  26. Psychrophiles
    • -Love the cold
    • -optimum temp below 15c
    • -capable growth 0c
    • -max temp/obligate and can not grow above 20
    • -storage at refrigerator temp incubates rather than inhibits them
    • - Rarely pathogenic
    • -natural habitats- algae, lakes rives snowfields polar ice and deep ocean
  27. Psychotrophs
    • Cold tolerant
    • - grow slowly in the cold but have an optimum temp between 15-30
    • S. aureus and listera monocytogenes able to grow at refrigerator temp and cause food born illness.
  28. Mesophiles
    • -Medically significant microorganisms
    • -grow intermediate temperatures between 20-40
    • inhabit animals and plants as well as soil and water in temperature, subtropical and tropical regions
    • human pathogens have optimal temp between 30-40c
  29. Thermoduric
    • Heat tolerant
    • - can survive short exposure to high temperature but are normally mesophiles
    • -Common contaminants of heated or pasteurized foods
    • -heat resistant cysts Giardia, Bacillius and Clostridium
  30. Thermophile
    • Heat loving
    • -grows optimally at temperatures greater than 45
    • -live in soil and water associated with volcanic activity, compost piles and in habitats directly exposed to sun
    • - most eukaryotic forms cannot survive above 60c

    Extreme thermophiles- grow between 80-100 archae
  31. Be able to discuss the strategies organisms use to deal with toxic oxygen products
    • Most cells have developed enzymes that scavenge and neutralize reactive oxygen byproducts
    • Two steps:
    • 1. 2O2- + 2H----(Superoxidize dismutase)--> H2O2 (hydrogen peroxide) + O2
    • hydrogen peroxide is toxic to cells- must be degraded by enzyme catalase into H2O+O2

    2. 2H2O2--(catalase)--> 2H2O + O2

    If microbe not capable of dealing with toxic O2 by these or similar mechanisms, it is forced to live in habitats free of O2
  32. How microbes process oxygen
    • -As oxygen enters cellular reactions, it is transformed into several toxic products
    • 1. singlet oxygen (o)- extremely reactive molecule that can damage and destroy a cell by oxidization of membrane lipids

    2. Superoxide ion (o2-) highly reactive

    3. hydrogen peroxide- (H2O2) toxic to cells and used as disinfectant 

    4. Hydroxyl radicals (OH-) also highly reactive
  33. Environmental Factors- pH
    • Defined as acidity or alkalinity
    • - the majority of organisms live or grow in habitats between 6 and 8 because strong acids and bases can be damaging to enzymes and other cellular substances.
    • Acidophiles
    • Alkalinophiles
  34. Environmental Factor- Osmotic Pressure
    • Osmophiles: live in habitats with high solute concentration
    • -halophiles- prefer high concentration of salt
    •    Obligate- grow optimally at solutions of 25% NaCl but require atleast 9% NaCl
    •    Facultative- remarkably resistant to salt even though they do not normally reside in high salt environments
  35. Environmental Factor: Radiation
    • - Phototrophs use viable light rays as an energy source
    • - Nonphotosynthetic microbes tend to be damaged by the toxic oxygen products produced by contact with light
    • -Some microbal species produce yellow carotenoid pigments to absorb and dismantle toxic oxygen
    • -Ultraviolet (non-ionizing) and ionizing radiation can be used in microbial control
  36. Aerobe
    can use gaseous oxygen in their metabolism and possess the enzymes needed to process toxic oxygen products

    • -obligate aerobe- cannot grow without oxygen
    • ie fungi, protozoa, many bacteria Bacillus, Mycobacterium tb
  37. microaerophiles
    do not grow at normal atmospheric concentrations of oxygen but require a small amount of it in their metabolism
  38. aerotolerant anareobes
    • do not utilize oxygen but can survive and grow to a limited extent in its presence. They are not harmed by oxygen mainly because they possess alternate mechanisms for breaking down peroxides and superoxide
    • ie lactobacilli and streptococci, clostridial species
  39. Facultative anaerobes
    Do not require oxygen for metabolism but use it when it is present. Can also perform anaerobic metabolism. ie gram negative intestinal bacteria, staphylococci
  40. Strict Anareobe
    Organism that does not oxygen to grow and survive

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