Chapter 4 : Bacterial Culture and Growth Flashcards
what are the three ways that microbes respond to their resources being depleted?
they can (1) die, (2) evolve to use what resources remain, or (3) cannibilize other microorganisms
what type of nutrients must an organism import from the immediate environment, otherwise it will not grow?
essential nutrients
what are nutrients that are needed in large quantities?
macronutrients
what are the 6 main macronutrients that are needed to make carbs, lipids, protein and nucleic acids in a cell?
C, N, P, H, O, N, and S
what are cofactors in terms of nutrients?
cations for specific enzymes (ex. Mg2+, Fe2+, K)
what type of nutrients are required in trace amounts, including Co, CU, Mn, Mb, Ni, and Zn?
micronutrients
what process breaks down multicarbon(organic) nutrients to CO2?
heterotrophy
what process reassembles CO2 into multicarbon nutrients thereby reducing CO2 to make carbohydrates that are consumed by heterotrophs?
autotrophy
what is the process wherein organic carbon sources are broken down in ways that generate energy through oxidation?
organotrophy
what are the two types of autotrophs?
photoautotrophs and chemolithotrophs
what do photoautotrophs do?
use light energy to fix CO2 into biomass
what do chemolithotrophs do?
fix CO2 using chemical reactions without light(Calvin cycle)
what do lithotrophs use for energy?
inorganic chemicals that they oxidize
what do organotrophs use for energy?
organic compounds that they oxidize
if a compound is more reduced, will it have a higher or lower potential energy yield?
higher, because it has more e- to give up
how is a membrane potential made?
chemical or light energy is used to pump protons outside of the cell, making cation concentration greater outside the cell
why can most organisms not use atmospheric N2?
its triple bonds are highly stable and require a lot of energy to break
what is a symbiont?
an organism that lives with another organism
what is the process wherein nutrients are transported from areas of higher to lower concentration (into a cell)?
facilitated diffusion
is facilitated diffusion an example of active or passive transport?
passive, as it does not use energy
for what type of molecule is facilitated diffusion generally used?
compounds that are too large or too polar to diffuse on their own
what is the name of the important membrane protein family that is responsible for transporting water and other small, polar molecules?
aquaporins
what process imports nutrients into the cell against a concentration gradient?
active transport
why is active transport important in aquatic and soil habitats?
in aquatic habitats, nutrient concentration is low; in soil habitats, competition for nutrients is fierce b/c of microbial abundance
how is active transport generally achieved?
ion gradient
what is symport in regards to ion gradient?
the two molecules involved in the “coupled transport” travel in the same direction
what is antiport in regards to ion gradient?
the two molecules involved in the “coupled transport” travel in the opposite direction
what are ABC transporters?
ATP-binding cassette transporters that use ATP to move molecules across the cell membrane
what do ABC transporters consist of?
two hydrophobic membrane proteins and two cytoplasmic proteins
what are secreted by the cell to bind ferric iron(Fe3+) and transport it into the cell where it is reduced?
siderophores
what type of growth covers the entire agar surface?
confluent growth
what type of medium is nutrient rich but poorly defined?
complex medium
what type of medium is a complex medium with specific nutrients added
enriched medium
what type of medium favors the growth of one organism over another?
selective medium
what type of medium exposes biochemical differences between organisms?
differential medium
what are specific nutrients that are not required by other species?
growth factors
when the growth curve is exponential, the growth rate is said to be proportional to the ________.
population size
what is the equation to find the number of organisms after a certain number of generations, given the initial population size?
N(final) = N(initial) x 2^n
n = number of generations
what is generation time?
amount of time it takes for a bacterial population to double; i.e., time required for one bacterial cell to divide into two daughter cells through binary fission
what is the formula to find generation time?
g = t / n
g = generation time
t = time elapsed
n = number of generations
what does the growth rate constant show?
rate of exponential growth
what is the formula to find the growth rate constant?
k = n / t
what are the four stages of a batch culture lifecycle?
- lag phase
- log phase (and late log phase if you count it)
- stationary phase
- death phase
what occurs during the lag phase?
cells that are transferred to new medium prepare for growth by making new enzymes to adjust to new nutrient sources and environment
what occurs during log phase?
exponential growth phase, balanced constant rates of growth, linear
what occurs during the late log phase?
rate of doubling slows, cells sense presence of others
what occurs during stationary phase?
cell density is too high compared to nutrient density, resulting in a plateau of population size on the curve
what occurs during death phase?
death rate is proportional to population size; exponential decline
what is a biofilm?
bacteria in nature that form specialized, surface-attached, collaborative communities
Pseudamonas aeruginose growing on the surfaces of the lungs in CF patients is an example of what?
biofilm
what are microbial spores?
they are secreted by cells and do not grow or need nutrients until germination; they have increased chemical and heat resistance
