topic 6 Flashcards
anabolism
consumes energy
- biosynthesis of macromolecules
catabolism
breaking things down
- energy for mobility
- transport of nutrients
- for bio synthesis
- fermentation of acids, alcohols, carbon dioxide
macronutrient requirements
- necessary to sustain by all cells
- carbon, nitrogen, phosphorus, oxygen
micronutrient requirements
- only by some cells in smaller amounts
- iron, copper, sodium, magnesium, Mn
energy sources
need to oxidate (gain electrons) for ETC
- photo
- -> extract electrons from organic and inorganic (cynobacteria)
- chemo
- -> organic or inorganic
where electrons for energy comes from
- from organic molecules like glucose
- from litho (rock) inorganic molecules like ammonia, water, sulfur
heterotroph
- get carbon source from fixed organic carbon (carbon-carbon bonds)
- eat biomass made by autotrophs
autotroph
- get carbon source from gaseous inorganic carbon dioxide
- primary producers, bottom of food chain
naming based on nutrient take up
(energy source) + (electrons source ) + (carbon source) + (troph)
- photo/ chemo + organo/ litho + hetero/auto + trop
chemoorganotrophs
energy from oxidation of organic compound
chemolithotrophs
energy from oxidation of inorganic compounds
only in prokaryotes
phototrophs
energy from light captured by pigments
oxygenic or anoxygenic
why need carbon?
- energy storage
- structural support
conservation of energy
capture energy and using it for other processes
nitrogen
- second most important to make amino acids, nucleic acids
- original form of ammonia
growth rate
dependent on amount of nutrients in environment
- plateaus because something eventually runs out
limiting factor
a key nutrient available in the lowest amount
aerobic growth
- obligate aerobes require oxygen
obligate anaerobes
cannot grow with oxygen
aerotolerant anaerobes
indifferent to oxygen
facultative anaerobes
grow in absence of oxygen but prefer when oxygen present
microaerophiles
grow best in low levels of oxygen
toxic oxygen species
- oxygen being the final electron acceptor in the ETC, has side reactions and production of reactive oxygen species that are bad
- -> oxygen isnt necessarily bad, just the side products
- are oxidizing agents, oxidize other things (gain electrons)
- rip electrons from dna, proteins and lipids and oxidize other molecules
- need enzymes to handle reactive oxygen to eliminate the reactive species
singlet oxygen (O2)
antioxidants, carotenoid pigment
superoxide anion (O2-)
cellular defense through enzymes superoxide dismutaste, super oxide reductase enzymes
hydroxyl radical (OH-)
due to reduction of oxygen during respiration and other redox reactions
cellular defense through antioxidants, glutathione
hydrogen peroxide
due to reduction of oxygen during respiration and other redox reactions
cellular defense with enzymes catalase and peroxidase remember
catalase test
hydrogen peroxide is converted to water and oxygen gas
h2o2 –> h2o + o2
positive test –> bubbling
negative test –> no bubble
effects of pH
cytoplasm at around neutral pH
- macromolecule structures
- transmembrane electrochemical gradients
- always an optimal ph range
- intracellular ph is relatively neutral
- in pH extremes intracellularly found to be 4.6-9.5
acidophiles
1-5.5 pH
neutrophiles
6 - 8.5 pH
alkalophiles
8.5 - 13.5 pH
osmotic pressure
solute concentration changes result in influx or efflux of water that can cause stress to cell by swelling or shrinking
water activity in cell
water is used for biochem reaction
- measure by water activity aw
- decrease in aw means increase in interaction with solutes
- pure water has water activity (aw) 1
- –> because measured by vapour pressure of air in equilibrium with sample/vapour pressure of air with pure water
- seawater has water activity (aw) 0.98
- bacteria require aw > 0.9
- measuring vapour pressure above a solution of water that allows assessment of moisture content
significance of water activity
allows us to understand which bacteria is mostly likely to grow where
- streptococcus and escherichia coli are able to survive water activity of human blood
- caulobacter and spirillium in pure water
theory of water activity
- water wants to move into cell
temperature
- affect macromolecule structure, membrane fluidity, enzyme function
- different optimal temperature growth ranges
psychrophiles
-15-10 degrees C
mesophiles
10-40 degrees C
thermophiles
55-80 degrees C
hyperthermophiles
80-120 degrees C
temperature response curve
optimum growth is at maximum possible rate of growth at a given temperature before…
- -> point of denaturation
- -> collapse of cytoplasmic membrane
- -> thermal lysis
chlamydomonas nivalis
of the snow
- snow algae, red snow, blood snow, watermelon snow
- carotenoids makes it red, accessor pigment of chlorophyll
- captures light energy, heat energy that melts snow and increases water activity
- high concentration of unsaturated fatty acids in membrane because very fluid membrane
- psychrophile
- -> less than 15 degree C for optimal temperature
- -> enzymes denature to moderate temperature
psychrotolerance
- able to grow 0 - 4 degree C
- optimal growth in moderate temperatures so mesophiles
- found in soil, creeks, and home temperature climates
- e coli
hyperthermophiles
supervolcano
boiling spring superheaded to 1-2 degree above boiling point
hot environments
soil during summer: 55 degrees compost: 55 degree hot spring: BO of water deep sea hydrothermal vents: 350 degree hot water heaters: <50 degree
molecular adaptations
- favour proteins and enzymes that will function optimally at higher temperatures
- amino acid substitutions in locations that produce heat tolerant folds
- resist unfolding in aqueous cytoplasm with ionic bonds between acidic and basic residues
- stabilize proteins with certain solutes
- saturated cytoplasm membranes, lower fluidity
media
solid media: agar plate - polysaccharide from algae solidfying agent - stays solid - liquid media: broth
complex media
- unknown chemical composition
defined media
known chemical composition
- need to be able to draw chemical structures as well as exact measurments
selective media
allows for isolation of microbes with specific properties
differential media
allows for certain microbes be recognized based on visual reactions in medium
enriched media
used to increase population of microbes with specific property
pure culture
- in a solid medium, cells are held in place on a surface and can be easily isolated
streak plate method
streaks, flaming inbetween, where u end up with pure isolated colony
spread plate method
0.1 mL sample spread on surface of agar plate with hockey sticks so colonies on surface of agar
pour plate method
1 mL of sample added to molten agar medium and poured into plate so bacterial colonies on surface and in agar
- must be thermotolerant ~40 degrees C
quantifying microbes
- direct count
counted under a microscope, loaded onto a chamber slide with grid - viable cell count
serial dilutions and CFUs (colony forming unit per mL) - turbidity measurements
spectrophotometer
- sends light through a culture
- light absorbance measure of cell density in tube
- doesnt work as well in death phase due to high levels of waste
four basic phases in the microbial growth curve
lag phase
- min amount of viable cell
- min turbidity
exponential phase
- after the lag phase, then exponential growth of growth and turbidity
stationary phase
- run out of nutritional need and plateau
death phase
- exponential decrease of viable cell and optical density with viable cell decrease much steeper than turbidity
generation time in microbial growth curve
time to double population
growth rate
of generations/unit of time, inverse of generation time
growth yield
max pop density/ amount of cellular material produced by culture
continuous culture
- always in exponential growth
- to keep microorganisms in limited but continuous flow
- chemostat flows fresh medium and takes out old medium
- rate of growth partly dictated by pump
control of microbial growth
- filtration
- -> sterilization purposes, or differential but need high pressure because pore sizes are very small
- -> wont work for viscous fluids only liquid and gas
- -> gentler than using heat
- temperature manipulation
- ->
- radiation
- ->
- chemical control
- ->
