Practice Exam Flashcards
T/F all bacteria double their numbers every 20 minutes.
False
Most bacteria increase in number through the process of
Binary fission
When comparing direct microscopic counts of microbial growth to plate counts, plate counts _______ tell you whether the cells are dead or alive
Will
Microbes will not be able to grow below their minimal temperatures because
Proteins denature
A pastry chef with poor personal hygiene inadvertently inoculate a crime puff with 100 Staphylococcus aureus cells. The crime puff sat on the bakery display shelf for four hours and was purchased and consumed by a college student on her way home from micro class. S. Aureus has a generation time of 20 minutes, approximately how many bacteria did the student eat?
409,600
Salts preserve foods by creating a(n) ______ relative to the inside of the cell
Hypertonic environment
As potential pathogens and the fact that they are growing on nutrient agar plates the organisms are most likely
Chemoorganoheterotrophs
which of the four microbial growth controls is/are physical methods to kill microbes
sterilization (ex. autoclave, gamma radiation)
which of the four microbial growth controls are chemical methods to kill microbes?
antiseptic
disinfectant
sanitize
physical and chemical methods are both _________ methods to kill microbes
nonspecific methods
how are antibiotics different from all of the methods to control microbial growth discussed this far?
antibiotics are specific and target a certain microbe (targeted towards pathogens - towards Bacteria)
bactericidal
kills bacteria
bacteriostatic
inhibits growth
Is penicillin considered bactericidal or bacteriostatic?
bactericidal - directly leading to death of organism (it prevents proper cell wall division)
which environment is most harmful to a bacterial cell?
hypertonic
plasmolysis can occur when a bacterial cell is placed into a ________ solution
hypertonic
the test tube of media shown (lots of growth on top and little distributed throughout tube) is likely to have which kind of organism in it?
facultative anaerobe
an obligate anaerobe will produce which enzyme?
neither catalase nor SOD
organisms that can tolerate environments with high salt concentrations, such as your skin, are ___________
halotolerant
write out the timeline of how antibiotic resistance developed
- penicillin was discovered
- more antibiotics discovered
- penicillin used (used widely in WW II) –> rapid decline in infections
- “magic bullet” - widespread use (decrease in research)
- antibiotic resistance started growing rapidly (where we are today)
plasmolysis
plasma membrane shrinks away from cell wall in hypertonic solution
- supposed to be close together (will screw up metabolism)
facultative anaerobe
has a preference to grow with oxygen because it is more endogenically favorable (more growth near top of culture)
what percent of salt can halophiles live in
1-15%
penicillin inhibits __________
peptidoglycan synthesis
cells divide at their maximal rates during ___________
log phase
what happens to cells at high temperatures?
cytoplasmic membrane collapses
nucleic acids denature
proteins denature
which of the following is false about the enzymes of acidophiles?
they have an activity optimum at pH below neutral
they will be denatured at high pH
they are found in soda lakes
they are found in low pH bogs
they are found in soda lakes
potato salad at a restaurant salad bar was inadvertently inoculated with 1 Salmonella cell. The potato salad sat at room temperature for 2 hours. Assuming that Salmonella has a generation time of 10 minutes, approximately how many bacteria were present after 2 hours?
4,096
when a halophile is placed in distilled water the cell is placed in a(n)
hypotonic environment
high temperatures are more lethal to cells than low temperatures. This is because
heat damage tends to be irreversible
the average temperature of the oceans is 5 degrees C. You would then predict that the majority of marine microorganisms would be
psychrophiles
why is molecular oxygen (O2) a toxic molecule for cells
free radicals produced during O2 reduction pull electrons off cellular components
what is the difference between an antiseptic and a disinfectant
disinfectants kill pathogens on inanimate surfaces, antiseptics kill pathogens on living tissues
what is the desired result of the quadrant streak plate technique
obtain will isolated bacterial colonies
what do we call an organism that grows best in the presence of low amounts of oxygen?
microaerophile
Bacillus cereus can grow in cooked rice while it is cooling in a refrigerator (from 45 C to 15 C), but not once it cools below 15C. Therefore B. cereus is a(n)
mesophile
which of the following statements about metabolism in prokaryotes is false?
a. anabolic reactions transfer energy to ATP
b. ATP is the link between anabolic and catabolic reactions
c. degradation reactions release energy
d. synthesis reactions use energy
A
the substrate in a reaction contacts a specific region of the enzyme molecule called the _______
active site
synthesis reactions ______ energy
use
degradation reactions ______ energy
release
ATP is the link between _______ and catabolic reactions
anabolic
what is a cofactor
the non-protein component of an enzyme
how many net ATP are produced from fermentation of glucose with ethanol as the fermentation end product
2
how many net ATP are produced from the fermentation of glucose with lactic acid as the fermentation end product?
2
Desulfovibrio use SO4 (sulfate) as a terminal electron acceptor, reducing it to H2S (hydrogen sulfide). These bacteria are _______
anaerobic respiring prokaryotes
which group of organisms would use oxygen as a terminal electron acceptor and utilize an electron transport chain
aerobic respirers
fertilizer is typically applied as NO3-, which of the following processes results in the conversion of NO3- to N gas
denitrification
the energy generated by catabolic pathways is used
to make cellular components
for motility
to transport substances across the cytoplasmic membrane
uses glucose for carbon and energy
chemoorganoheterotroph
uses CO2 for carbon and H2 for energy
chemolithoautotroph
which of the following is the best definition of fermentation
oxidation of glucose with an internal organic molecule serving as the electron acceptor
which of the following is the best definition of glycolysis
oxidation of glucose to pyruvate
which of the following is not necessary for respiration
oxygen
a strictly fermentative organism produces energy
by glycolysis only
which of the following is not an end-product of fermentation
a. lactic acid b. pyruvate
c. ethanol d. CO2
pyruvate
sterilization
destroys all viable cells, spores, and viruses
antiseptic
kill pathogens on living tissue
sanitize
lowers number of pathogens on a surface to an acceptable level
disinfectant
kill pathogens on inanimate objects
define oxidation-reduction
a coupled reaction in which one substance loses electrons and another gains electrons
define aerobic respiration
the final electron acceptor is molecular oxygen
define anaerobic respiration
the final electron acceptor is another inorganic molecule
define respiration
an ETC is used , the final electron acceptor is usually inorganic
define fermentation
an ETC is not used
the final electron acceptor is usually organic
define cyclic photphosphorylation
electrons are returned to chlorophyll
define noncyclic photophosphorylation
chlorophyll receives electrons from hydrogen atoms
why must NADH be reoxidized
NAD+ is needed to pick up more electrons
How does this happen in an organism that uses repiration? Fermentation? (Why must NADH be reoxidized)
NADH is usually reoxidized in respiration
NADH can be reoxidized in fermentation
which reaction produces the most molecules of ATP during aerobic metabolism?
acetyl CoA –> CO2 + H2O
which of the following compounds has the greatest amount of energy for a cell?
glucose
which of the following is the best definition of the Krebs cycle?
a series of chemical reactions in which NADH is produced from the oxidation of pyruvic acid
which of the following is the best definition of respiration?
a sequence of carrier molecules with an inorganic molecule as the final electron acceptor
which culture produces the most lactic acid?
E. coli growing in glucose broth at 35 C without O2 for 5 days
which culture produces the most ATP
E. coli growing in glucose broth at 35 C with O2 for 5 days
which culture uses NAD+?
E. coli growing in glucose broth at 35 C with and without O2 for five days
describe binary fission
the cell elongates, and the chromosome replicates. Next the nuclear material is evenly divided. The plasma membrane invaginates toward the center of the cell. The cell wall thickens and grows inward between the membrane invaginations; two new cells result
macronutrients are often listed as CHNOPS. What does each of these letters indicate, and why are they needed by the cell?
C: carbon - synthesis of molecules that make up a living cell
H: hydrogen - source of electrons and component of organic molecules
N: nitrogen - component of amino acids
O: oxygen - component of organic molecules
P: phosphorous - in phosolipids and nucleic acids
S: sulfur - in some amino acids
seven methods of measuring microbial growth are explained in this chapter (6). Categorize each as either a direct or an indirect method.
direct methods are those in which the microorganisms are seen and counted. Direct methods are direct microscope count, plate count, filtration, and most probable number.
by deep-freezing, bacteria can be stored without harm for extended periods. Why do refrigeration and freezing preserve foods?
the growth rate of bacteria slows down with decreasing temperatures. Mesophilic bacteria will grow slowly at refrigeration temps and will remain domain in a freezer. Bacteria will not spoil food quickly in a refrigerator
nitrogen and phosphorous added to beaches following an oil spill encourage the growth of natural oil-degrading bacteria. Explain why the bacteria do not grow if nitrogen and phosphorous are not added.
petroleum can meet the carbon and energy requirements for an oil-degrading bacterium however nitrogen and phosphate are usually not available in large quantities. Nitrogen and phosphorous are essential for making proteins, phospholipids, nucleic acids, and ATP
differentiate complex and chemically defined media
a chemically defined medium is one in which the exact chemical composition is known
a complex medium is one in which the exact chemical composition is not known
the term trace elements refers to
small mineral requirements
which one of the following temperatures would most likely kill a mesophile
60 C
which of the following types of media would not be used to culture aerobes
a. selective
b. reducing
c. enrichment
d. differential
e. complex
reducing media
an organism that has peroxidase and superoxide dismutase but lacks catalase is most likely an
aerotolerant anaerobe
catabolism
chemical reactions that result in the breakdown of more complex organic molecules into simpler substances
catabolic reactions ________ energy
release
anabolism
chemical reactions in which similar substances are combined to form more complex molecules
anabolic reactions__________ energy
use
the energy of catabolic reactions is used to drive _______ reactions
anabolic
the energy for chemical reactions is stored in _______
ATP
enzymes are generally _____ proteins
globular
most enzymes are __________, consisting of a protein portion and a nonprotein portion
holoenzymes
protein portion
apoenzyme
nonprotein portion
cofactor
at high temperatures, enzymes undergo ________ and lose their catalytic properties
denaturation
optimum pH
the pH at which enzymatic activity is maximal
enzymatic activity increases as substrate concentration _______ until the enzymes are saturated
increases
oxidation
the removal of one or more electrons from a substrate
protons (H+) are often removed with the electrons
reduction
gain of one or more electrons
NAD+ is the _______ form
oxidized
NADH is the ________ form
reduced
glucose is a ______ molecule
reduced
addition of a Pi to a molecule is called ________
phosphorylation
most of a cell’s energy is produced from the ________ of carbohydrates
oxidation
________ is the most commonly used carbohydrate
glucose
the two major types of glucose catabolism are _______ and fermentation
respiration
respiration
glucose is completely broken down
fermentation
glucose is partially broken down
the most common pathway for the oxidation of glucose is _______
glycolysis
______ is the end-product of glycolysis
pyruvic
_____ ATP and 2 NADH molecules are produced from one glucose molecule
2
during respiration, ________ are oxidized
organic molecules
in aerobic respiration, _____ functions as the final electron acceptor
O2
in anaerobic respiration, the final electron acceptor is usually an _______ molecule other than O2
inorganic molecule
fermentation ______ energy from sugars or other organic molecules by ________
releases
oxidation
______ is not required in fermentation
O2
electrons removed from the substrate _______ NAD+ (fermentation)
reduce
fermentation: the final electron acceptor is an ________ molecule
organic
in lactic acid fermentation, ________ is reduced by NADH to lactic acid
pyruvic acid
_______ hydrolyze lipids into glycerol and fatty acids
lipases
fatty acids and other hydrocarbons are catabolized by ________
oxidation
catabolic products can be further broken down in glycolysis and ________
Krebs cycle
photosynthesis
the conversion of light energy from the sun into chemical energy; the chemical energy is used for carbon fixation
in cyclic phosphorylation, the electrons return to the ________
chlorophyll
in oxidation-reduction reactions, energy is derived from the _______ of electrons
transfer
to produce energy, a cell needs an _________
electron donor, a system of electron carriers, and a final electron acceptor
photoautotrophs
obtain energy by phosphorylation and fix carbon from CO2 via the Calvin-Benson cycle to synthesize organic compounds
cyanobacteria are oxygenic _________
phototrophs
Green bacteria and purple bacteria are anoxygenic _______
phototrophs
_____________ use inorganic compounds as their energy source and carbon dioxide as their carbon source
chemoautotrophs
__________ use complex organic molecules as their carbon and energy sources
chemoheterotrophs
amino acids are required for _______
protein biosynthesis
psychrophiles
cold-loving
mesophiles
moderate-temperature-loving
thermophiles
heat-loving
optimum growth
temperature at which it grows best
minimum growth temperature
the lowest temperature at which a species will grow
maximum growth temperature
highest temperature at which growth is possible
most bacteria grow best at a pH value between _____ and ____
6.5-7.5
in a ________ solution, most microbes undergo plasmolysis
hypertonic
________ can tolerate high salt concentrations
halophiles
_________ use an organic molecule as their carbon source
chemoheterotrophs
________ typically use carbon dioxide as their carbon source
autotrophs
microbes in biofilms are more resistant to ______ than are free-swimming microbes
antibiotics
generation time
the time required for a cell to divide or a population to double
bacterial division occurs according to a ______ progression
logarithmic
during the _______ phase, there is little or no change in the number of cells, but metabolic activity is high
lag
during the ______ phase, the bacteria multiply at the fastest rate possible under the conditions provided
log
during the _______ phase, there is an equilibrium between cell division and death
stationary
