Ch. 7: Microbial nutrition, ecology, & growth Flashcards
The term chemotroph refers to an organism that
gets energy by oxidizing inorganic & organic chemical compounds.
Organisms that feed on dead organisms for nutrients are called
saprobes.
Aerobic respiration is an example of
chemoheterotrophy.
The methanogens, producers of methane gas, require environments that
are anaerobic with hydrogen gas and CO2.
The use of energy by a cell to enclose a substance in its membrane by forming a vacuole and engulfing it is called
endocytosis.
The movement of molecules from an area of high concentration to an area of lower concentration is called
diffusion.
Facilitated diffusion and active transport require __________________ to mediate the movement across the plasma membrane.
a carrier protein
The movement of substances from lower to higher concentration across a semipermeable membrane that must have a specific protein carrier and cell expenditure of energy is called
active transport.
What kind of microorganisms would find hypotonic conditions very detrimental?
protozoa
In ________ conditions, the cell wall will help prevent the cell from bursting.
hypotonic
A cell with 1% salt inside lives in the ocean, which is 3% salt. This is what kind of environment?
Hypertonic
An organism with a temperature growth range of 50°C to 70°C would be called
thermophile
Cultures of a bacterial species were incubated at various temperatures. After incubation, there was no growth at 37°C and 70°C, but abundant growth in the refrigerator. What term could be used for this species?
Psychrophile
A microorganism that does not have catalase or superoxide dismutase would find it difficult to live in an environment with
oxygen.
Which two enzymes, and in what order, catalyze the steps converting the toxic superoxide ion to less harmful oxygen gas?
superoxide dismutase and catalase
The E. coli that normally live in the human large intestines and produce vitamin K that the body uses would be best termed a ________ relationship.
mutualistic
When microbes in close nutritional relationship and one benefits but the other is not harmed, it is called
commensalism.
The phase of the bacterial growth curve in which newly inoculated cells are adjusting to their new environment, metabolizing but not growing is the
lag phase.
The phase of the bacterial growth curve that shows the maximum rate of cell division is the
log phase.
viable cell count only measures:
living things
Which tool is so expensive that it is not used at most hospitals in the world?
flow cytometer
autotroph
a microorganism that requires only inorganic nutrients and whose sole source of carbon is carbon dioxide.
active transport
nutrient transport method that requires carrier proteins in the membranes of the living cells and the expenditure of energy
chemoautotrophs
an organism that relies upon inorganic chemicals for its energy and carbon dioxide for its carbon; AKA chemolithotroph
diffusion
passive dispersal of molecules, ions, or microscopic particles propelled down a concentration gradient by spontaneous random motion to achieve a uniform distribution
this is also called: Brownian Motion [random movement displayed by small particles that are suspended in fluids]
facilitated diffusion:
passive movement of a substance across a plasma membrane from an area of higher concentration to lower concentration utilizing specialized carrier proteins
-energy not required
heterotroph
organism that relies upon organic compounds and other living things for its carbon and energy needs
Carbon source- organic carbon
hypotonic
A solution that, when compared with a reference solution, is less concentrated; Ex) has more water and less solute
-when a membrane is placed between this solution and a hypertonic solution, water will move from the hypotonic side to hypertonic side at a higher rate
hypertonic
a solution that, when compared to a reference solution, has a higher concentration of solute and less water; placed opposite a hypotonic solution, it will cause water to diffuse more rapidly from the hypotonic solution, thus creating a greater osmotic pressure.
Isotonic
solution having the same osmotic pressure, such that, when separated by a semipermeable membrane, show no net movement of solvent in either direction
passive transport
nutrient transport method that follows basic physical laws and does not require direct energy input from the cell.
photoautotroph
microbe that uses sunlight for energy and Co2 as carbon source
phagocytosis
a type of endocytosis in which the cell membrane actively engulfs large particles or cells into vesicles
-Phagocyte is a cell specialized for doing this
psychrophile
a microorganism that thrives at low temperatures 0-20 C, with a temperature optimum of 0-15 C.
-likes close to freezing water temperature; can appear red in the snow “watermelon snow”
quorom sensing
a phenomenon occurring among microbes in biofilm in which the members signal each other and coordinate their functions.
endocytosis
process whereby solid and liquid materials are taken into the cell through membrane invagination and engulfment into a vesicle
mesophile
microorganism that grow at intermediate temperatures — usually between 20-40 C.
-room temperature/human body temperature; most medically significant group
facultative parasite
an organism that may resort to parasitic activity, but does not absolutely rely on any host for completion of its life cycle. It is not completely dependent on host.
facultative anaerobe
bacteria that can grow in both the presence or absence of oxygen.
what are the 6 important elements to all living things?
carbon
nitrogen
hydrogen
oxygen
phosphorus
sulfur
organic vs inorganic
organic nutrients have usually at least 1 hydrogen and carbon
why is iron an important micronutrient for bacteria?
bacteria use it to promote invasion in body tissues
why is zinc an important micronutrient for bacteria?
in some viruses, zinc can bind to glycoprotein on the surface of the host cell; which blocks viral adsorption [first step of replication]; can reduce the severity/duration of cold symptoms
what is the balanced chemical equation for photosynthesis?
6CO2 + 6H2O + sunlight > C6H12O6+ 602
Oxygenic (produces oxygen gas)
what is the balanced chemical equation for chemoheterotrophs?
Aerobic respiration-
C6H12O6 + 602 > 6CO2 + 6H20 + 36 - 38 ATP
ectoparasite
live on the external surface of another organism
ex) ticks, fleas, lice, parasitic flies and mites
endoparasite
lives in the body of another organism
intracellular parasite
live inside cells of a host cell
pathogens
parasites that cause disease/death
photoautotrophs and chemoautotrophs obtain their carbon from-
Co2
osmosis
water moving across cell membrane (from high to low concentration)
a cell in a hypertonic environment will :
shrink / become distorted
a cell in a hypotonic environment will :
swell & may burst if there is no mechanism to remove the water in the cell
pinocytosis
[will not focus on this much in class]
taking in liquid (oil droplets..)
cardinal range of microbes
range of temperatures where a cell/microbe can survive and grow
-below this range: cellular activity (like enzymatic reactions) are inhibited, so cell may become dormant and stop growing
-above this range: enzymes would become inactive and denatured/ be destroyed- so cell may die
-minimum, optimum, and maximum #
Optimum is the optimal temperature for reproduction
psychrotroph
grow slowly in the cold; can have some pathogens in this group; grows from 5-35 C.
hypothermophile / extreme thermophile /extremophile
can grow at very high temps. 80-120 degrees C (250 F)
-pressure necessary for this high temp
-deep sea hydrothermal vents/ yellow stone
which temperature would a psychrophile enjoy?
10 degrees celcius
[0-15/20]
what are the 3 types of aerobic organisms?
Obligate aerobe- make catalase and superoxide dismutase [can only grow at top of a test tube, bc needs oxygen]
Facultative anaerobe- capable of fermentation; can grow without oxygen, but grow better with oxygen; lots of pathogens in this group; produce catalase and superoxide dismutase
Microaerophile- grow in subatmospheric concentrations of oxygen [small amounts of oxygen required]
what are the 5 toxic oxygen byproducts?
what are the 2 types of anaerobes?
Obligate / strict anaerobe- killed by normal atmospheric concentrations of oxygen; lack superoxide dismutase and catalase; can be transferred between hosts but transfer time is limited, oxygen for extended period of time = death.
EX) cavities in teeth and in intestines
Aerotolerant anaerobe- they can survive in oxygen
how can you culture anaerobic microbes?
- work in a hood that is pumped full of high pressure nitrogen gas which excludes oxygen from being in the work area
OR
- innoculate petri plates, place inside bins that can eliminate oxygen
What is a symbiotic relationship and what are the 3 types?
Symbiotic- required for at least 1 partner for survival
—Mutualism- both parties benefit from interaction [E. coli & humans]
—Commensalism- 1 partner benefits and other does not really care [skin flake eating microbes]
—Parasitism- salmonella, giardia, malaria, etc… we would rather they not be around but they need us for survival [all viruses]
What is a non-symbiotic relationship and what are the 2 types?
Non-symbiotic- not required for either partner
—Synergism- 2 organisms helping each other out but not necessary for survival [ex) organisms inside of a biofilm, they grow and create a nice environment for each other]
—Antagonism (amensalism)- competition for space/food/moisture, etc..
Draw a population growth curve
describe the 4 phases of microbial growth
Lag- looks like nothing is happening; cell is gearing up for cell division; it is copying its DNA which takes long time…DNA replication
Log rhythmic/ log/ exponential— growth; optimal rate of growth will continue if there is nutrients & space…
Stationary — growth levels out, division slowed, cell death is increasing; population remaining the same; running out of food and space
Death – due to build-up of waste products (toxic, poop, salt…)— does not go to Zero
during which phase of the population growth curve do bacteria run out of food?
stationary
viable cell count
just counting living cells ; cannot figure out how many dead cells; accurate and cheap [ just need a petri plate ] ; can take at least a day
Methods of analyzing populations
Turbidity:
Spectrophotometer:
turbidity- looking for cloudiness in a liquid culture = rough estimate how many dead and living cells there are
spectrophotometer: passes light through culture/test tube; the more light reaches through, the less cloudy, and the less growth you have; relative scale of cloudiness to obtain doubling time; very inaccurate; dead and living cells; immediate reading
slide cytometer
more accurate assessment of cell count in culture
-actually count how many cells there are in the slide
-counting living and dead cells
flow cytometer
laser beams shines on a single cell dropping out of a narrow tube
—costs millions of dollars, only used in labs
-extremely precise; differentiate between living and dead cells and different cell types
chemostat
provides fresh medium and nutrients; removes waste, dead cells, and pharmaceutical chemical …
provides microbes with food to keep them in log phase/ early stationary phase, to make as much pharmaceutical as they can;
ex) insulin, HGH made with this
what are the 2 types of autotrophs?
photo & chemo
what are 2 types of heterotrophs?
where do they get their carbon?
chemoheterotroph (saprobes- fungi, bacteria, some protists; or symbiotic microbes- parasites, commensals, mutualistic)
Photoheterotroph (purple sulfur bacteria- purple and green photosynthetic bacteria)
Carbon source = organic carbon
