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165 Cards in this Set
- Front
- Back
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Microbiology
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biology of small orgamisms (<1mm) too small to be seen with unaided eye-- but not all are microscopic
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Microbiology
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methods of study - use of microbiological methods (isolation and culture or an organism from a mixed population)
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meat and maggot experiment
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disproved theory of spontaneous generation until microscope
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Anton van Leeuwenhoek
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- 1st to observe microbes under microscope.
- revived theory of spontaneous generation |
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Louis Pasteur
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- refutes theory of spontaneous generation with experiments
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Louis Pasteur
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- use of SWAN NECK flasks to keep growth media sterile
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Louis Pasteur
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- developed STERILE TECHNIQUE of tissue culture
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role of microbes in disease
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evidence in mid 1800s- effect of fungi in causing silkworm disease and potato blight
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Joseph Lister
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INDIRECT evidence for microbes as causative agents of human disease
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Joseph Lister
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antiseptic agents that kill microbes also prevent surgical infections; birth of antiseptic surgery
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Robert Koch
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DIRECT evidence that microbes cause disease through study of anthrax.
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Robert Koch
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developed GERM THEORY of disease
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Robert Koch
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mouse experiments
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1. microbe must be present in all cases of disease and absent from healthy orgs.
2. putative pathogen must be isolated and grown in pure culture 3. isolated org. must cause same disease in a healthy host 4. same organism must be isolated again from newly diseased host |
Koch's Postulates
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1. cut and boiled potatoes: unreliable
2. addition of gelatin to liquid broth: better but gelatin melts at 30degrees and digested by some bacteria 3. use of agar: very successful- add nutrient broth to agar 4. development of petri dish |
culture of bacteria on solid media
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Pasteur
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demonstrated that fermentations were the result of microbial activity
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Carbs, lipics, nucleic acids, proteins
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Biological macromolecules
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70% H2O; 30% chemicals
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cell composition
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20
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number of elements found in biological macromolecules (living orgs.)
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CHOPSN
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6 elements found in high amounts in living orgs.
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covalent bonds
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- strong bonds
- formed and broken by enzymes |
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Hydrogen bonds
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- weak bonds- form and break spontaneously
- between H and more electroneg. element (N,O) |
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Carbohydrates (sugars)
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- act as energy source
- constituent of cell wall - component of nucleic acids |
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carbs
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glycosidic bonds
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lipids
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insoluble in H2O; soluble in non-polar organic solvents
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lipids
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- important energy source
- constituent of cell membranes |
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lipids
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simple fat- glycerol and fatty acids
complex- simple and additional cmpd sterols- cholesterol-like fats |
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Nucleic Acids
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made of nucleotide monomers
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nucleic acids
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polymers= DNA and RNA
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Proteins
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amino acid monomers
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proteins
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connected by peptide bonds
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proteins
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most known enzymes (some are RNAs)
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proteins
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form important structural components of cells
- eukaryotic cytoskeleton - muscles- actin |
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primary structure
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linear order of amino acids
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secondary structure
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shape along single axis in space
- alpha helix, beta sheet |
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tertiary structure
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3-D organization of the individual secondary structures
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quarternary structure
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occurs when a protein has more than one subunit. shows how subunits associate with each other
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primary, secondary, tertiary
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all proteins have what structures? (TQ!)
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secondary, tertiary, quarternary
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what protein structures are stabilized by non-covalent bonds (H and disulfide)?
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primary
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what protein structure is stabilized by covalent bonds?
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produce an enlarged image of an object
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what is the function of a microscope
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simple microscope
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single lense (magnifying glass)
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comound microscope
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more than one lense (most microscopes today)
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- prisms bend light
- lenses act like collections of prisms - magnifying power= strength |
principles of lenses
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high mag.
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small focal length (fat lense) = high or low mag?
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low mag
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long focal length (thin lense)= high or low mag
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light microscope
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use of light to produce an image
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electron microscope
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use of electrons to produce image
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1. light source
2. stage 3. condenser 4. objective lenses 5. eyepiece lense (ocular) |
1. provides illumination
2. platform for holding slides 3. focus light on slides 4. REAL primary image (TQ!) 5. magnifies primary image- VIRTUAL secondary image |
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objective mag X eyepiece mag
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Total magnification calculation (TQ!)
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resolution
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ability to distinguish 2 very close objects as distinct entities.
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resolution
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measured as the min. distance (d) to distinguish between 2 objects that reveal them as separate entities. the smaller the value of d the better (d= .5wavelength/NA)
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bright field microscope
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produces a dark image on a bright background. mainly used to observe fixed and stained (dead) cells
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dark field microscope
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used to observe living and unstained cells. produces bright image on dark background
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phase- contrast microscope
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used to observe living and unstained cells. enhances contrast btwn intracellular structures having slight differences in refractive index (bright around edges)
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electron microscope
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microscope that uses electromagnets instead of glass lenses and electrons instead of light
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transmission EM
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reveals great detail of internal structure of cells (2-D image). slice sample into thin layers- can reconstruct 3-D image
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scanning EM
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reveals great detail of external structure of cells (3-D image)
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Fixation of a specimen
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required for preservation of cell structure and also attaching specimen to slide
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heat- quick and convenient; not good for preserving cell structure
chemical- time consuming; good for preserving cell structure and shape |
2 ways to "fixate" a specimen
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staining of a specimen
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required for "seeing" certain cellular structures through use of dyes
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1. simple staining
2. differential staining |
What kind of staining
1. use of a single dye 2. use of >1 dye |
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prokaryotes
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bacteria, archae
no nuclear membrane |
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eukaryotes
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algae, fungi/yeast, protozoa
possess nuclear membranes |
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cocci
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Shapes of bacterial cells
spheres gram + (exception= Neisseria) |
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bacilli
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Shapes of bacterial cells
rods gram - (exception bacilli) |
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1. no membrane bound organelles
2. cell wall- external to plasma or cell membrane |
prokaryotic cell structure
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plasma membrane
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what prokaryotic cell structure?
- encloses cytoplasm, selectively permeable, comprised of proteins and lipids, lack cholesterol but have cholesterol-like HOPANOIDS which control fluidity of membrane |
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protoplast
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plasma membrane + cytoplasm
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integral protein
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protein embedded in membrane and also amphipathic. Not static but can diffuse in plane of memrane
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peripheral protein
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protein with loose association with membrane
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cytoplasm
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what prokaryotic cell structure?
- mostly water (75%), harbors nucleoid, ribosomes, inclusion bodies |
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ribosomes
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one of the main components of translation machinery
- 2 subunits made of proteins and rRNA |
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large= 50 s
small= 30s total = 70s |
prokaryotic ribosome size
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inclusion bodies
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what prokaryotic cell structure?
- act as storage granules for nutrients- contains organic or inorganic material |
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Nucleoid
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contains the genetic material (DNA), RNA, and proteins (necessary for compaction)
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nucleoid
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almost always a single circular chromosome, chromosome associated with the plasma membrane (attached at the mesosome)
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Gram +
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Cell wall and PG (thick)
(Gram + or -) |
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Gram -
has membrane which makes it hard to treat with drugs |
plasma membrane and PG (thin) and outer membrane
(Gram + or -) |
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cell wall
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consists of all structures external to plasma membrane
(gram +) |
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NAG and NAM
alternating D and L aa's connected to NAM |
Peptidoglycan subunits= 2 linked glucose derivatives
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gram +
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aa # 3= L-Lysine
(Gram + or -) |
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gram -
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aa # 3= DAP
(Gram + or -) |
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shape and protection from osmotic lysis
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Role of PG
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osmotic lysis
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lots of salt inside cell- water flows in to make conce= in and out
cell expands and bursts b/c membrane not strong enough |
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btwn aa #3 and 4
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linkage of PG subunits
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Gram + cell
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- thick PG
- large quantities of TA |
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Gram - cell
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- more complex
- thin PG - includes outer membrane containing LPS or endotoxin - more permeable than plasma membrane |
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capsule
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prokaryotic structure
- outside cell wall - not seen in all bacteria - helps resist phagocytosis by white blood cels - enhances adherence to host tissues |
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Pili or Fimbriae (same)
- sex pili larger than regular |
- short, hair-like structures on cell surface
- role in attachment to host tissues - important for twitching and gliding motility of some bacteria |
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flagella
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used for motility for most bacteria
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bacterial endospores
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dormant structures formed as protection in response to adverse environmental conditions. only formed by a few bacteria
- contain large amts of DPA |
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eukaryotic cells
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characterized by presence of membrane bound organelles which provide environment for distinct metabolic rxns.
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cytoplasmic matrix (inside plasma membrane)
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Eukaryotic structure
- mostly water (75%) - harbors organelles and cytoskeleton |
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cytoskeleton
(prokaryotes have their own version) |
important for cell shape and motion
- filamentous components |
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ER
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eukaryote structure
- network of tubules and flat sacs involved in protein and lipid transport |
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rough ER
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involved in intracellular transport and "modification" of secreted proteins
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smooth ER
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involved in lipid metabolism and detox of chemicals
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Golgi
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series of flattened sacs in close association with the ER
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Golgi
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receives material from ER and acts as a packaging and sorting organelle for transport of lipids
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lysosomes
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synthesized by ER/Golgi system
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lysosomes
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required for intracellular digestion of macromolecules and destruction of ingested microbes
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lysosomes
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contain a class of enzymes called HYDROLASES that function at a low pH (hydrolyze macromolecules)
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ER, Golgi, lysosomes, endosomes (vaculoes formed when plasma memrane engulfs extracellular material)
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cellular import/export system.. in order
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eukar ribosomes
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organelles of protein synthesis
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nucleus
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membrane bound organelle containing linear chromosomes
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large= 60s
small= 40s total= 80s |
eukar ribosome subunits sizes
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nucleus
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eukar structure
chromosomes packaged into CHROMATIN by proteins known as HISTONES |
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nucleus
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eukar structure
-contains a prominent NUCLEOLUS, site of rRNA synthesis and assembly of ribosomal sub-units |
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nucleolus
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site of rRNA synthesis and assembly of ribosomal sub-units
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cristae
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site of respiration
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thylakoid membrane (chloroplast)
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site of photosynthesis
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mitochondrial matrix
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eukar. structure
- contains DNA and bateria-like (70s) ribosomes |
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nutrient
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compound required for biosynthesis and energy
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CHOPNS
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major elements
- required in g/L amounts |
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K, Ca, Mg, Fe, Na
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minor elements
- required in mg/L amounts |
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minor elements
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required as enzyme co-factors or for activity of certain enzymes
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C, P, Na
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macroelements
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Mn, Zn, Co, Ni, Mo, Cu
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Microelements (trace elements)
- required as enzyme co-factors or for activity of certain enzymes - microgram/L amts |
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carbon energy electrons
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Microbial classification based on sources of nutrient and energy acquisition
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carbon
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backbone of all organic molecules
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autotrophs
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use CO2 as sole or main source of carbon
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heterotrophs
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use organic molecules pre-formed by other organism
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phototrophs
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light as energy source
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chemotrophs
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oxidation of organic and inorganic compounds as energy source
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lithotrophs
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"rock eaters" reduced inorganic molecules as electron source
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organotrophs
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use organic cmpds as a source of electrons
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-synthesis of important molecules
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N, P, S required for:
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- organic cmpds
- essential cell components (or their precursors) that the cell cannot synthesize - must be supplied by environment if cell is to survive and reproduce |
growth factors
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- selective
- accumulation against concentration gradient (for most) - movement across barrier- plasma membrane - Gram - has to cross outermembrane too, so crosses 2 membranes |
nutrient uptake
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passive diffusion
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very inefficient and not an important means of nutrient uptake
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facilitated diffusion
- faster than passive b/c concentration gradient is still necessary |
to increase the rate of diffusion, cells utilize carrier proteins known as PERMEASES (plasma membrane proteins) to transport cmpds.
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chemical modification (phosphorylation) of transported compound
- requires energy input - found in prokaryotes |
group translocation
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active transport
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requires the expenditure of chemical energy to move molecules "uphill" against a gradient.
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permease, energy, substrate change
1. none 2. permease 3. permease, energy 4. permease, energy, substrate change |
Nutrient Transport Mechanism
1. passive 2. facilitated 3. active 4. group translocation |
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endocytosis
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- take nutrients in
- found in eukar - solutes or particles enclosed in vesicles pinched off from plasma membrane - vesicles fuse w/ lysosome to digest material and release nutrients- break down into smaller usable parts |
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- samples are collected from cold environments
- psychrophilic (cold-loving) bacteria are isolated and cultured |
isolation of bacteria from environ.
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psychrophilic
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cold-loving bacteria
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known chemical composition
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defined/synthetic culture medium
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unknown chem. composition, but "rich"
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complex culture medium
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permits growth of only certain microbes in a mixed pop. (growth vs. no growth)
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selective culture medium
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distinguishes btwn different subsets of microbes (lactose fermenting and non-fermenting microbes)- different appearance
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differential culture medium
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no add. of nutrients or removal of waste products. over time nutrients inc. and waste dec.
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closed system
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(first) lag phase
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no increase (flat), synthesis of new cellular components
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(second) exponential phase
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maximal growth rate, constant growth rate (cell # doubles atregular time intervals), phase when cell pop is most chemically and physiologically uniform
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(third) stationary phase
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# viable orgs remains constant
- death rate= growth rate so no net inc. or dec. |
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(fourth) death phase
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decrease in viable count, log decreae
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measured during exponential phase, time for a 2-fold increase in cell # (TQ!)
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doubling or generation time
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# generations/unit time
ex. generations per hour |
growth rate constant
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direct counting
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count # cells in a chamber of known volume (petroff-hauser chamber)
- adv= quick and simple - disadv= NOT viable cell count |
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electronic counting
- NOT a viable count |
microbial suspension forced through small orifice
- movement of microbe through orifice impacts electric current that flows through (coulter counter) - instances of disruption of current are counted |
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viable counts: spread plate, pour plate
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perform serial dilutions of sample and determine # cells
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# colonies forming units per ml.
(# colonies/vol. plated) |
# viable cells
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more cells= more scattered light= OD
- OD= amount of light that DOESNT get through - high OD= more cells - NOT viable count |
optical density
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growth in constant environment
- steady provision of nutrients and waste removal - growth maintained at exponential rate |
open system- chemostat
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for most cells, higher the salt (osmolarity), the more difficult it is to grow: due to PLASMOLYSIS- removal of water from cell
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osmolarity
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prefer growth in high salt environments
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HALOPHILES
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model for life on mars
- can survive in salt deposits after water evaporates |
extreme halophiles
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min, optimum, max
- prokar. can grow at much higher temps than eukar. |
Cardinal temps
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low optimum temp
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PSYCHROPHILES
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20- 40 degrees optimum (most humans)
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MESOPHILES
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high optimum (>55)
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THERMOPHILES
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preferred growth environ. can be classified as:
- acidophile - neutrophiles - alkalophiles |
pH
- cytoplasmic pH of most orgs is close to neutral |
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oxygen
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final electron acceptor for aerobic respiration
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1. need oxygen
2. prefer oxygen 3. ignore O2 (doesnt matter) 4. oxygen is toxic 5. < 2-10% oxygen (low level) |
1. obligate aerobe
2. facultative anaerobe 3. aerotolerant anaerobe 4. strict anaerobe 5. microaerophile |
