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.
mesophile
microorganism that grow at intermediate temperatures — usually between 20-40 C.
-room temperature/human body temperature; most medically significant group
a cell in a hypertonic environment will :
shrink / become distorted
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
what are the 5 toxic oxygen byproducts?
Draw a population growth curve
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
