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;
29 Cards in this Set
- Front
- Back
|
Q1 Bacterial Growth
|
Bacterial growth refers to the numbers of cells, not the size of the cells. Microbes that are 'growing' are increasing in number.
|
|
|
Q1 Factors Affecting Growth
|
- temperature
- pH - Osmotic Pressure |
|
|
Q1 Define a colony
|
A colony is is a group of cells large enough to be seen without a microscope. There can be many (colonies).
|
|
|
Q1 How can Prokaryotes reproduce?
|
-Binary Fission (most common)
-budding -conidiospores (actinomycetes) -fragmentation of filments |
|
|
Q1 Details of Binary Fission
|
-Cell elongates and DNA is replicated
-Cells wall and plasma membrane begin to constrict. -cross-walls forms completely separating the two DNA copies -cells separate |
|
|
Q2 Name groups of microorganisms based on their preferred temperature range
|
-psychrophiles (very cold-loving)
-psychrotrophs (cold/refrigerator) -mesophiles (moderate/like us) -thermophiles (heat loving) -hyperthermophiles (extreme heat) |
|
|
Q3 How is pH important in microbial growth
|
-most bacteria 6.5 -- 7.5
-molds & yeasts pH 5 -- 6 -acidophiles (acid loving) pH < 7 |
|
|
Q3 How is Osmotic pressure (pressure surrounding microbe) important in microbial growth
|
- hypertonic environment (high solute), causes plasmolysis. Water leaves cell, cell can die.
Example: meat packed in salt. --Isotonic - outside environment .85% NaCl. (things are equal) |
|
|
Q3 Define extreme/obligate halophiles
|
-Require high osmotic pressure. Like high salt outside.
|
|
|
Q3 Define facultative halophles
|
- can tolerate high salt concentration but not required.
|
|
|
Q4 Chemical requirements for growth
|
-CARBON (all macromolecules)
-chemoheterotrophs use organic carbon for energy and carbon source -autotrophs use C02 as their carbon source -nitrogen: amino acids proteins -sulfur: amino acids -phosphorus: DNA, RNA ATP -trace elements -organic growth factors from environment |
|
|
Q5 Classify microorganisms on basis of oxygen requirements
|
-Needed for some, poison to some
-OBLIGATE AEROBES:needs air -FACULTATIVE ANAEROBES:w/without AIR. Greater growth w/air. -OBLIGATE ANAEROBES: 02 is poison. -AEROTOLERANT ANAEROBES:ignores O2 -Microaerophles: tolerates 02, not much. |
|
|
Q5 What allows microbes to use/tolerate oxygen
|
-Enzymes. OBLIGATE and FACULTATIVE have them. OBLIGATE ANAEROBES dont. AEROTOLERANT one enzyme, MICROE... none.
|
|
|
Q6 Distinguish between chemically defined media and complex media
|
-both are culture media that are nutrients prepared for microbial growth.
CDM - exact chemical composition known. Complex Media: extract and digest of yeasts, meats or plants: nutrient broth(liquid) or nutrient agar(solid). |
|
|
Q6 define sterile, inoculum and culture
|
-Sterile - no living microbes
-Inoculum - microbes introduced into medium Culture: microbes growing in/on culture medium |
|
|
Q7 Define use of this culture methods: selective and differential media
|
-SELECTIVE Media: surpresses unwanted microbes and encourages desired microbes. Ex: McConkey Agar, encourages gram - bacteria, suppresses gram + bacteria.
-Differential Media: makes it easy to distinguish colonies of different microbes. Ex: Blood Agar. (between streps) |
|
|
Q7 What are Enrichment Procedures?
|
Procedures to increase small levels of a microbe to detectable levels. using enrichment culture. If microbe can only grow using phonol for carbon and energy, put it in that culture. After growth period, put small sample in another plate. Good for soil/fecal samples.
|
|
|
Q7 What are anaerobic media and techniques?
|
Media used to grow anaerobes(o2 deadly). Called Reducing Media. Contains ingredients combinewith dissolved oxygen and deplete it. They are heated. can be an anaerobic JAR, of chamber.
|
|
|
Q7 What is a candle jars?
|
Candle Jar: used to create a high CO2, low oxygen environment within a jar. Cultures in Jar, sealed, candle lit,goes out whe O2 low.
|
|
|
Q8 What is a capnophiles?
|
Microbes that grow better in high CO2, low O2 concentrations, such as a candle jar.
|
|
|
Q7 What are living host cells?
|
Used when a bacteria can't be grown in an artificial laboratory media. Example Leprocy bacillus. Can be grown in armadillos
|
|
|
Q8 How are pure cultures isolated using streak plates
|
(1) sterile loop dipped into a mixed culture, >1 type microbe
(2) First streak is top third, horizontaly. (3) 2nd streak, picks up culture from kright end of top streak and is streaked vertically on right third. (3) third streak picks up from bottom of 2nd streak and is streaked vertically on bottom third. Last cells rubbed grow into isolated colonies. Can be transferred to test tube to form a pure culture. |
|
|
Q9 Define Generation Time
|
Generation Time: the time required for a cell to divide and its population to double. Varies greatly among bacteria, from 1 to 3 hrs, some greater than 24 hrs.
|
|
|
Q10 Name and describe phases of the bacterial growth curve.
|
-Lag phase: intense activity preparing for growth
-Log phase: exponential (logarithmic) increase in population -Stationary phase: equlibrium/living and death equal -Death phase; decrease at logarithmic rate. |
|
|
Q11 What are several direct measurements of microbial growth?
|
DIRECT: (1) PLATE COUNTS- perform serial dilutions of a sample. Each one contains 1/10 cells preceding Final count at 10 X power.
PLATE COUNT: Spread Plate and Pour Plate. Filtration, and Direct Microscopic Count |
|
|
Q11 What are several indirect measurements of microbe growth?
|
Turbidity: Cloudiness
Dry Weight of filamentous bacteria Metabolic Activity Measure gaseous byproducts. |
|
|
Q12 Terms for destruction or supression of microbial growth:
-Sterilization -Disinfection -Antisepsis -Germicide |
-Sterilization: Removal of all microbial life.
-Disinfection: removal of pathogens from non-living Tissue -Antisepsis: Removal of pathogens from living tissue Germicide: Kills microbes |
|
|
Q12 Terms : Bacteriostasis, asepsis, degerming, sanitization
|
Bacteriostasis: inhibiting, not killing microbies.
Asepsis: absense of significant contamination Degerming: removal of microbes from a limited area (shot) Sanitization: lower microbial counts on eating utensils. |
|
|
Q13 Physical methods of microbial Control:
--moist heat --dry heat --pasteurization --filtration |
--Moist Heat: denatures proteins. example an autoclave
--Dry Heat: kills by oxidation, flaming(lab), incinerationhot-air oven. --Pasteurization: reduces spoilage organisms and pathogens --Filtration of air: removes microbes |
