Reading...
Play button
Play button
Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
45 Cards in this Set
- Front
- Back
|
Define microbial growth
|
an increase in the number of cells in a population
acheived by binary fission (typically) |
|
|
Define binary fission
|
process of creating daughter cells where each cell is left with a copy of DNA
|
|
|
What is generation or doubling time?
|
length of time for one cell to become two cells
|
|
|
what is the culture bias concerning binary fission?
|
? pg 201 of text
|
|
|
Describe two influences on generation time
|
ways the cells make energy
Speed of DNA replication |
|
|
what are the terms that describe the carbon source of bacterial nutrition? Define each
|
Autotrophs - use inorganic forms of carbon source, such as CO2
Heterotrophs - use organic sources of carbon, such as any macromolecule or subunit |
|
|
What are the terms that describe the energy source of bacterial nutrition? Define each.
|
Phototrophs - capture energy from sunlight
Chemotrophs - use organic or inorganic molecules for energy - Chemoorganotrophs - organic molecules - Chemolithotrophs - inorganic molecules |
|
|
What is a photoautotroph?
|
energy source = sun
carbon source = CO2 |
|
|
What is a chemolithoautotroph?
|
energy source = inorganic chem
carbon source = CO2 |
|
|
What is a chemoorganoheterotroph?
|
energy source = organic chem
carbon source = organic macromolecules |
|
|
What is a solution?
|
Solute (substance being dissolved) and solvent (dissolving substance)
|
|
|
What is osmosis?
|
movement of water from high water/low solute to low water/higher solute concentration; known as movement down a concentration gradient
|
|
|
What does selectively permeable cell membrane mean?
|
Some molecules can pass freely
Other molecules have to be specifically transported |
|
|
What is cell lysis?
|
cell wall bursting open when too much water moves into the cell
|
|
|
What protects the cell from lysis?
|
Cell wall
|
|
|
What happens when too much water leaves a cell?
|
cell shrinks when the solute concentration is higher outside the cell as water moves out of it
|
|
|
What is simple diffusion?
|
movement of solutes from high concentration to low concentration
-does not require expending energy -movement along concentration gradient -only small, nonpolar molecules |
|
|
What is facilitated diffusion?
|
process of using special proteins that span the cell membrane to transport a solute (polar molecule)
- does not require expending energy - along concentration gradient |
|
|
What is specificity?
|
refers to facilitated diffusion
-specific transport protein will transport specific nutrient based on shape |
|
|
What is saturation?
|
refers to facilitated diffusion
- rate of transport is limited by number of transport proteins in a membrane - ie. if 3 transport proteins exist, if there are 3 or more molecules for these transport proteins, they are saturated |
|
|
What is competition?
|
refers to facilitated diffusion
- if two nutrients have similar shape they can "compete" for access to transport protein; usually higher concentration is preferentially transported |
|
|
What is active transport?
|
Energy is used to transport molecules against concentration gradient; and also for use along concentration gradient, faster
-used for nutrients that cell needs a constant supply of, mono or disaccharides, inorganic ions and amino acids -carrier mediated |
|
|
What is a psychrophile?
|
Cold temperature growth preference, 0-20 C
|
|
|
What is a mesophile?
|
Room temperature+ growth preference, 20-40 C
|
|
|
What is a thermophile?
|
Warm temperature growth preference, 45-80 C
|
|
|
What is a hyperthermophile?
|
Hottest temperature growth preference, 80-120 C
|
|
|
What are the toxic byproducts of oxygen? What do they do to microbes?
|
Superoxide radical (O2-) and Hydrogen Peroxide (H2O2)
They damage DNA and membrane lipids, which damages selective permeability |
|
|
What is the enzyme that breaks down the Superoxide radical?
|
Superoxide dismutase enzyme
|
|
|
What is the enzyme that breaks down hydrogen peroxide? What forms if hydrogen peroxide is not broken down?
|
catalase enzyme
Free hydroxide radicals form is H2O2 is not broken down (HO-) |
|
|
What is an obligate anaerobe?
|
Must have an oxygen-free environment because it does not have superoxide dismutase or catalase enzymes to destroy toxic oxygen byproducts
|
|
|
What is an obligate aerobe?
|
Requires oxygen for growth
- has both enzymes, superoxide dismutase and catalase |
|
|
What is a facultative anaerobe?
|
microbe that grows better when oxygen is present but can grow without oxygen too.
-posesses both superoxide dismutase and catalase enzymes |
|
|
What is a microaerophile?
|
microbe that grows best in limited oxygen environments; some enzymes cannot function in full O2 concentrations
|
|
|
What is an aerotolerant anaerobe?
|
Microbe that can tolerate any oxygen condition; growth is more limited when O2 is present
-doesn't have enzymes but has other mechanisms for dealing with O2 byproducts |
|
|
What is an acidophile?
|
microbe that likes acidic environments
- very acidic pH 1 such as stomach |
|
|
What is a neutrophile?
|
Microbe that grows optimally at a neutral pH
|
|
|
What is a alkalinophile?
|
microbe that prefers a basic pH environment, up to pH of 10, ie hot ponds or soils high in basic minerals
|
|
|
What is an obligate halophile?
|
microbe that requires high salt concentration for growth
- optimal conc is 25% (ocean is approx 3.5% salt) - Great salt lake is 5-27%, dependent on rainfall |
|
|
What is a facultative halophile?
|
microbes that can tolerate high salt concentrations but do not require it
- S. aureus .1% - 20%; all staph genus are facultative halophiles |
|
|
Describe the bacterial growth lab. What does it help to describe?
|
To observe growth curve
-closed or batch system where no more nutrients are added and waste is not removed -maintain specific temperature, usually for optimal growth -shaking water bath to maintain consistent levels of O2; |
|
|
What is the lag phase of the growth curve?
|
Period of adaptation where bacteria analyze what is present and what it needs to make in order to multiply
- no increase in number of cells - generate ATP for energy - length of phase varies with species and conditions provided |
|
|
What is the exponential growth phase or log phase?
|
Population doubles each generation
Primary metabolites are synthesized - product of chemical reaction in cells - amino acids, nucleotides, subunits of macromolecules Late exponential growth phase - secondary metabolites are synthesized (such as antibiotics that will kill other cells so cell can reduce competition for nutrients) |
|
|
What is the stationary growth phase?
|
Growth curve flat lines
population growth ceases new growth = death rate in some cells, stress causes endospores to form that are heat resistant and allow them to survive harsh conditions |
|
|
What is the death phase?
|
New cells are not necessarily being formed as old cells die off
|
|
|
At what growth phase are endospores typically made?
|
Stationary growth phase
|
