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what are the morphologies of bacterial cells
- coccus (cocci)
- bacillus (bacilli)
what is the morphology of coccus
sperical. perfect spheres
what is the morphology of bacillus
rod. perfect rods
what is the morphology of coccobacillus
vibrio look like?
short curved rods
spirillium look like
pleomorphic shapes are
variable. each cell looks different
extracellular layer that holds bacterial cells together after cell division
what is the good news of an organism that forms groups?
it spreads more slowly
what is the bad news of an organism that forms groups?
it can hide from the Immune system longer
allows bacteria to move from on place to another.
alls cells to swim freely through an aquesous habitat.
what are the three subtypes of flagella ?
- - monotrichous
- - lophotricphous
- - amphitrichous
what is monotrichous
flagella with a single flagellum
what is lophotricphous
flagella with small bunches/tufts/groups of flagella emerging from the same site
what is amphitrichous
with flagella at both poles of the cell
what is peritrchious flagella?
arrangement of flagella are dispersed randomly over the surface of the cell
flagella can detect and move to chemical signals this type of behavior is called
ex: toward food and away from stimulus such as chemical toxins
movement of a cell in the direction of a favorable chemicial stimuulus/ attractant (usually a nutrient)
movement away from a repellent (potientially harmful) compound.
in chemotaxis for flagella when it is swimming toward attractant the flagella will
swim/run more and tumble less
with flagella, if the bacteria is moving toward a repellent the flagella will
tumble more and swim for shorter periods.
swim toward/away from light
swim toward/away from oxygen supply
moving toward/away from magnetic field. coordinates movement in response to magnetic fields. ex: orient to earth's magnetic field
small, bristlelike fibers emerging from the surface of many bacterial cells.
- most contain protein.
- tendency to stick to each other/ and surfaces.
elongated, rigid tubular structure made of special protein.
-only in gram-negative where they are utilized in "mating"
mating process between cells.
involves partial transfer of DNA of one cell to another.
they may be responsible for the mutual clinging of cells that leads to biofilsm and other thick aggregates of cells on the surface of liquids and for the microbial colonization of inanimate solids such as rock and glass
some pathogens can colonize and infect host tissues b/c of tight adhesion between their what?
- fimbrae and epithelial cells
- ex: gonoccus-agent of gonorrhea colonizes the genitourinary tract E. Coli colonizes the intestine by this means
in the conjugation of pilus. a pilus from a donor cell unites with a recipent cell thereby providing...
cytoplasmic connection for making the transfer
inner most part of a bacterial cell
forms thick layer over inner cell membrane. where cell walls gain their stability and strength from
protects the cell from osmotic shock
definition: a network of polysaccharide chains cross-linked by short peptides hat from the rigid part of bacterial cell walls
a peptide inter-bridge between the Diaminopimelic Acid of one glycana chain and the D-Alanine of another. the composition of this inter-bridge varies between species
the tetrapeptides are joined directly
examples: rubber cement, weak, soluble
ex: rubber car tire, strong, tough, insoluble, lasts longer
definition: think homogeneous sheath of peptidoglycan ranging from 20 to 80nm in thickness. also contains tightly bound acidic polysaccharides including: teichoic acid directly attached to peptidoglycan and lipoteichoic acid
a polymer of ribitol or glycerol and phosphate embedded in peptidoglycan sheath. project outward from peptidoglycan layer. immunogenic
attached to the lipids in the plasma membrane.
project inward from peptidoglycan layer to cytoplasmic membrane- anchor.
composed of an outer membrane and thinner shell of peptidoglycan. contains specialized types of LPS and lipoproteins.
no peptide inter-bridge
composed of lipid molecules bound to polysaccharides. the lipids form the matrix of the top laye of the OM and the polysaccharides strand project from the lipid surface.
resistant to certain antibiotics
inserted in the upper layer of the outer membrane. they have some regulatory control over molecules entering and leaving the cell.
many qualities of the selective permeability of gram-negative bacteria to bile, disinfectants, and drugs are due to the
just underneath the outer membrane.
above and below peptidoglycan
important reaction site for a large and varied pool of substances that enter and leave the cell.
houses secreted degradative enzymes (pathology)
disrupts cross-linking between glycan molecules (makes the pepto layer weak)
more effective against gram+ b/c its excluded by prions in gram-
largerly composed of mycolic acid making them appear waxy and more resistant to chemicas, dehydration, antibiotics (pathology)
bacteria without a cell wall
containssterols that make it resistant to lysis
found in may habitats such as plants, soils and animals
form or shape. tendency for cells of same species to vary in some extent in shape in size.
mycoplasmas are this
contain peptidoglycan and stain gram-positive, but the bulk of their cell wall is composed of unique types of lipids.
underneath the cell wall
regulates transport into/out of the cell
flexible sheet molded completely around the cytoplasm
lipid bilayer with proteins emedded to varying degrees
- cell membrane
- 50% phospholipid
- 50% integral membrane proteis
polar head oriented toward the outside
nonpolar head towad the center of the membrane
embedded at numerous sites in this bilayer of various-size globular proteins
freely permeable to water, dissolves gases, and small hydrophobic molecules by simple diffusion
too big to go through cells
ex: glucose and amino acids
how do bacteria acquire most of their raw materials?
what are the types of transport proteins?
transport of two substances in the same direction
transport of 2 substances in opposite directions
transports one substance in one direction (either in or out)
ex: cations, potassium, calcium
clever (esp. for bacteria)
the substance is chemically altered during transport (phosphotranserase system)
ex: glucose and other sugars
the cell can soak up all the glucose by converting into glucose-phosphate
how do bacteria sense and respond to their environment?
transduce chemical signals from outside the cell to inside the cell
a single, circular, supercoiled, double stranded DNA molecule.
replicates only when the cell divides
what are the types of bacterial chromosome
where one gene goes so do all the other (little variation)
single bacterial chromosome
easier to replicate than linear (humans have linear)
circular bacterial chromosome
like, ours and replicates like ours
dsDNA bacterial chromosomes
inside the bacterial cell
the molecular machine that assembles amino acids into proteins
comprised of 54 proteins and 3 RNAs
target of many antibiotics
withstands hostile conditions and faciliate survival.
dormant bodies produced by bacteria Bacillus, and Clostridium.
two-phase life cycle taht shifts between a vegative cell and an endospore
exists in an inert, resting condition that is capable of high resistance and very long-term survival.
the time required for a complete fission of cycle. from parent cell to 2 new cells is called
generation or doubling time
the period between an individuals's birth and the time of producing offspring. in bacteria each new fission cycle increases the population by a factor of 2, or doubles it
a measure of the growth rate of an organism
compared with the growth rates of most other living things, bacteria are notoriously rapid.
average for bacteria is 30-60
- the number of bacteria at a certain time
- (what you have to try and calculate)
the number of bacteria at the beginning
the number of times the bacteria divide
how do you get n?
- 1st in the generation time divide 60 min by those mins. for ex: if generation time was 20. divide 60 by 20 = 3
- 2nd: times the answer for generation time by the elasped time to get n.
- to solve for nt:
- replace the value for n into the equation :)
what do you get when nutrients are limited?
- growth curve
- it takes a little while for them to get inot your blood stream.
what are the stages of growth curve?
- lap phase
- log phase
- stationary phase
- death phase
period of adjustment
no increase in cell number
cells dont divide
flat period on the graph when the population appears not to be growing or is growing at less than the exponential rate
cell number doubles every generation
(caused by unlimited nutrients)
no net incrase/decrease in cell number
(cell division = cell dealths)
(caused by depleted nutrients/build-up of toxic by products)
net decreased in cell number
caused by prolonged stationary phase
what are major factors that control bacterial cell growth?
- oxygen availability
- energy/carbon source
- what avialability/concentration of water
what is the temperatuure requirement for psychrophiles (many pseudomonas) ?
below room temperature
what are the temperature requirements for mesophiles (e. coli and all human pathogens) ?
about room temperature
what are the temperature requirements for thermophiles ( lactobacillus delbruekii- yogurt)?
above room temperature
what are the temperature requirements for hyperthermophiles (pyrolobus fumarimii -ocean vents)?
require the level of oxygen normally present in air
require the absence of oxygen
can grow in the presence OR absence of oxygen but grow faster with oxygen
require reduced levels of oxygen
grow equally well in the presence as in the absence of oxygen.
(they dont use oxygen at all so doesnt matter)
types of energy sources
derives its energy from the sun (plants)
derives its energy from organic compounds (us, glucose, fatty acids)
derives its energy from inorganic sources (rocks)
what are the carbon sources
derives carbon from CO2
derives carbon from organic compounds (sugars/amino acids/fatty acids)
what are the combinations of carbon sources
derives energy from the sun AND carbon from CO2
derives its eergy from organic compounds AND its carbon from organic compounds
derives its energy from the sun AND its carbon from organic compounds
ph sources are
grow best from pH 5 to pH 8 (most bacteria)
grow best pH 5 (heliobacter pylori)
grow best above pH 8 (Bacillius alcalophiles) few but not many
what is a water availability source?
tolerant to relatively high (10%) salt concentrations (staphylococcus some Archae)
what are factors to consider in control?
- 1. type of organism
- 2. number of organisms present
- 3. environmental conditions
list the types of organisms we learned, from hardest to control to easiest.
- 1. prions
- 2. endospores
- 3. mycobacteria
- 4. pseudomonas
- 5. non-enveloped viruses
- 6. vegetative bacterial cells/ enveloped viruses
explain the number or organisms present as a factor to consider in control
- decimal reduction time Dvalue
- D value = time nessary to kill 90%
explain the environmental conditions to consider in control?
pH, temp, salt, (smoke) water
what is the D value graph
- REMEMBER START AT 0 and the given amount of bacteria to start with , then go each interval that is given ex: if D =30 go every 30 minutes 1000 bacteria to start w/
- 0 --1000
- 30 min--- 100
- 1hr 30min---1
- 2 hrs--- less than 1
- DONT FORGET to go until you have less than 1!!!
what are physical methods for reducing bacterial populations?
200 degrees C for 1.5 hours to for sterile (wire loop)
121 degrees C for 15 mins for sterile
dehydrate vegetative cells
- (chemical control of bacterial populations)
denature proteins disrupt the 3 d structure
- (chemical control of bacterial populations)
ehtylene oxide (chemical control of bacterial populations)
oxidizing agents (chemically alter proteins)
- (chemical control of bacterial populations)
react with sulfhydral groups (Hg)
- (chemical control of bacterial populations)
ozone (chemical control of bacterial populations)
peroxides (chemical control of bacterial populations)
destroy cell membrane/proteins (chloraspetic)
phenolics(chemical control of bacterial populations)
quatemary ammonium compounds (quats)
(chemical control of bacterial populations)
types of radiation and bacterial populations
what do gamma rays do
penetrating, ionizing radiation to free radicals (very reactive)
what are ultraviolet rays
non penetrating to thymine dimers (TT) mutagenic
what do x-rays do
penetrating, ionizing radiation to double strand breaks in DNA (mutagenic)
prevent population from getting bigger
kill bacteria and decrase the size of the population
classified based on their chemical structure, mechanism of action, and biological source
- why is this important? if one type of antibiotic is ineffective a mechanistically different antibiotic should be used
- effective against: gram-positive bacteria
- mechanism: inhibtis cross linking of cell way peptidolycan
- examples: penicillins and cephalosporins
- examples:ampicillin and amoxycillin
- effective against: gram-positive and gram-neg
- mechanism: inhibits cross linking of cell wall ( peptidoglycan)
- examples:clavamox (is clavulanic acid plus amoxycillin)
- effective against:beta lactam resistant gram-positive and gram-neg bacteria
- mechanism:suicide inhibitor of beta-lactamases (clavulanic acid)
mechaism: inhibits translation (ribosomes) rna and the protein. if it cant make protein then it dies.
- examples: Vancomycin
- effective against: gram-positive bacteria, esp. staphylococcus aureus mrsa
- mechanism: inhibits steps in murein (component of the cell wall) (peptidoglycan) biosysnthesis
- example: polymyxin
- effective against/spectrum: gram-neg bacteria
- mechanism: damages cytoplasmic membranes
- example: rifampicin
- spectrum:gram-pos and gram-neg bacteria, esp. mycobacterium tuberculosis
- mechanism: inhibits transcription (RNA polymerase)
- example: amphotericin (strephtomyces nodosus), nystatin(strephomyces noursei)
- spectrum: fungi (candida)
- mechanism: inactivate membrances containing sterols