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57 Cards in this Set
- Front
- Back
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Principles of Bacterial Growth-- Prokaryotic cells divide by ________ ________. |
Binary fission |
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Principles of Bacterial Growth-- Exponential growth |
One cell becomes 2, then 4, then 8, then 16, etc. |
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Generation Time |
Time it takes to divide once. Varies among species. |
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Principles of Bacterial Growth-- T or F: Generation time also depends on environmental conditions. |
True |
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Principles of Bacterial Growth-- Calculating number of cells in a population: What is N1? |
number of cells in a population at a given time |
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Principles of Bacterial Growth-- Calculating number of cells in a population: What is N0? |
number of cells in the original population
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Principles of Bacterial Growth-- Calculating number of cells in a population: What is n? |
number of divisions a population has undergone in that time. |
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Principles of Bacterial Growth-- Calculating number of cells in a population equation: |
N1 = N0 * 2n (the n should be at the top of the 2) |
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Principles of Bacterial Growth-- Calculating number of cells in a population example: |
10 cells, generation time 20 min, splits in 4 hours N1 = 10 * 212 (2 to the 12th) N1 = 40,960 (10 is the # of cells in the original population) (12 is calculated by: if # of cells double every 20 minutes, that is 3 times an hour for 4 hours) |
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Growth Curve (picture on p.97)-- What are the 5 stages? |
--Exponential (Log) Phase --Stationary Phase --Death Phase --Phase of Prolonged Decline |
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What happens during Lag Phase? |
--cells begin synthesizing enzymes required for growth |
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What happens during Exponential (Log) Phase? |
--generation time is measured --end of phase endospores form |
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Growth Curve-- In what phase are bacteria most susceptible to antibiotics? |
Exponential (Log) Phase |
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Growth Curve-- What happens during Stationary Phase? |
--total numbers remain constant |
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Growth Curve-- What happens during Death Phase? |
--cells die at constant rate |
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Growth Curve-- What happens during Phase of Prolonged Decline? |
--cells have adapted to tolerate worsened conditions |
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Environmental Factors that influence microbial growth-- What kind of environments can prokaryotes inhabit? |
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Environmental Factors that influence microbial growth-- Extremophiles like what kind of environment? |
harsh
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Environmental Factors that influence microbial growth-- Name major conditions that influence growth. |
--pH --water availability --atmosphere-levels of oxygen |
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Temp requirements-- Each species of microbe has a temperature range that is best for its survival. Where is optima growth? |
Optimal growth is usually close to upper end of range. |
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Psychrophile |
minus 5 degrees C to 15 degrees C (in arctic and Antarctic regions) |
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Psychrotroph |
20 degrees C to 30 degrees C (causes food spoilage in fridge) |
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Mesophile |
25 degrees C to 45 degrees C (major group of human disease causers)
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Temp requirements-- Thermophiles |
45 degrees C to 70 degrees C (too warm to cause human disease. Has economical value) |
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pH-- Bacteria survive at a range of pH but have optimum ranges. Where do most maintain a constant internal pH? |
most maintain a constant internal pH, typically near neutral 7.0
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pH-- Most microbes are ________. |
neutrophiles |
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pH-- What is the range of pH for neutrophiles? |
pH range of 5 to 8 |
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What is the optimum pH for neutrophiles? |
near pH 7 |
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Where does H.pylori grow and at what pH? |
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pH-- What does H. pylori do? |
it produces urease to split urea into CO2 and ammonia (helping it survive in the stomach)
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All organisms require _____ for growth. |
water |
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Water availability-- How do dissolved salts and sugars affect a cell? |
--They make water unavailable to the cell, causing cells to die or at least slow their growth (hypertonic environment). --This is why we salt meat and use strawberry preserves. |
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Water availability-- T or F: Some microbes withstand or even require high salt. |
True |
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What is halotolerant? |
--need high salt concentrations --example: staphylococcus |
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Oxygen requirements (4.3 page 101)-- Do obligate aerobes require oxygen for growth? |
yes |
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Oxygen requirements-- What is an example of an obligate aerobe? |
Micrococcus Luteus |
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Oxygen requirements-- Where in the tube are obligate aerobes found? |
top of tube |
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Oxygen requirements-- Do obligate anaerobes require oxygen? |
No and they are sometimes killed after brief exposure |
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Oxygen requirements-- What is an example of an obligate anaerobe? |
Clostridium botulinum |
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Oxygen requirements-- Where in the tube are obligate anaerobes found? |
bottom of tube |
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Oxygen requirements-- Do facultative anaerobes require oxygen? |
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Oxygen requirements-- What is an example of a facultative anaerobe? |
E. Coli |
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Oxygen requirements-- Where in the tube are facultative anaerobes found? |
concentrated at the top of tube, but are everywhere in the media |
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Oxygen requirements-- Do microaerophiles require oxygen? |
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Oxygen requirements-- What is an example of a microaerophile? |
H. pylori |
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Oxygen requirements-- Where in the tube are microaerophiles found? |
middle of tube |
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Oxygen requirements-- Do aerotolerant anaerobes require oxygen? |
They don't care if oxygen is present or not. They won't use it. |
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Oxygen requirements-- What are aerotolerant anaerobes also known as? |
obligate fermenters |
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Oxygen requirements-- What is an example of an aerotolerant anaerobe? |
streptococcus pyogenes |
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Where in the tube are Aerotolerant Anaerobes found? |
hard to tell by a tube. need to use other tests. |
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Oxygen requirements-- Any organism that uses oxygen must be able to eliminate ________ ________ ________. |
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Using O2 in aerobic respiration produces harmful reactive oxygen species (ROS) as by-products such as... |
--hydrogen peroxide (H2O2) --free radicals like superoxide (O2-) |
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Oxygen requirements-- Superoxide dismutase inactivates superoxide (O2-) by converting it to... |
O2 and H2O2 (hydrogen peroxide) |
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Oxygen requirements-- Almost all organisms produce ________ ________. |
catalase enzyme |
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Catalase enzyme converts hydrogen peroxide (H2O2) to what? |
O2 and H2O (water) which is safe for the cell. |
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Oxygen requirements-- What is a catalase test? |
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This is why hydrogen peroxide will kill some bacteria. |
--they can't make enough catalase to break it down or they don't make catalase/they can't get rid of it |
