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Microbiology :O > Chp. 6 > Flashcards

Chp. 6 Flashcards

(50 cards)

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1
Q

What is the minimum, optimum, and maximum growth temperature?

A

Minimum: lowest temp a microbe can grow and have metabolism

Maximum: highest temp that a microbe can grow and have metabolism

Optimum: Promotes fastest rate of growth and metabolism (~37 degrees celsius)

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2
Q

TRUE OR FALSE: Psychrophiles grow best under cold temperatures under 15 degrees celsius

A

TRUE

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3
Q

Where are psychrophiles normally found?

A

Permanently cold environments like the polar regions and glaciers

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4
Q

Which organism is responsible for food spoilage at refrigerator temperature?

A

Listeria monocytogenes

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5
Q

What happens to microbial reproductive rates at low temperature?

A

It inhibits or slows down reproductive rates

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6
Q

What is the optimum growth temperature for:
- mesophile
- extreme thermophile
- thermophile
- psychrophile
- psychotrophs

A

Mesophile: 20-40 degrees celsius

Extreme thermophile: >80 degrees celsius

Thermophile: 50-60 degrees celsius

Psychrophile: <15 degrees celsius

Psychotrophs: between 0 and 20-30 degrees celsius

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7
Q

The pH that most bacteria grow best is ______

A

6-8

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8
Q

Mold and yeast grow best at which pH?

A

5-6

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9
Q

Organisms that grow at extreme acid pH are known as ______

A

Acidophiles

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10
Q

Organisms that grow at extreme basic pH are known as _____

A

Alkalinophiles

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11
Q

Organisms that require a high concentration of salt to survive are known as ____

A

Halophiles

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12
Q

Organisms that can tolerate high osmotic pressure but is not ideal to live in are known as ______

A

Facultative halophiles

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13
Q

Organisms that get their energy from chemical compounds are known as _____

A

Chemotrophs

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14
Q

Organisms that rely on consuming other organisms for energy are known as ______

A

Chemoheterotrophs

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15
Q

What happens to bacteria when put into hypertonic and hypotonic solutions?

A
  • Hypertonic solutions can cause plasmolysis due to high osmotic pressure, causing the cell to shrivel
  • Hypotonic solutions can cause the bacteria to swell and lyse due to low osmotic pressure
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16
Q

What are the 10 chemical requirements for growth?

A
  • carbon
  • hydrogen
  • nitrogen
  • phosphorus
  • oxygen
  • sulfur
  • potassium
  • calcium
  • magnesium
  • trace elements like iron and zinc
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17
Q

*Why is water required for growth?

A
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18
Q

Why is carbon needed for growth?

A
  • It is the structural backbone of organic molecules
  • Chemoheterotrophs use organic molecules as energy
  • Autotrophs use CO2
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19
Q

Why is nitrogen needed for growth?

A
  • It is a component of proteins, DNA, and ATP
  • Most bacteria decompose protein material for the nitrogen source
  • Some bacteria use NH4+ or NO3- from organic material and a few use N2 for nitrogen fixation
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20
Q

Why is sulfur needed for growth?

A
  • It is used in amino acids, thiamine, and biotin
  • Most bacteria decompose protein for the sulfur source
  • Some bacteria use SO42- or H2S
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21
Q

Why is phosphorus needed for growth?

Study These Flashcards
A
  • Used in DNA, RNA, and ATP
  • Found in membranes
  • PO43- is a source of phosphorus
22
Q

What is nitrogen fixation?

Study These Flashcards
A

When bacteria convert the N2 in the atmosphere to nitrates and nitrites and incorporate it into their DNA and ATP as usable nitrogen

23
Q

What does it mean when organisms are symbiotic? What are different types of symbiotic relationships?

Study These Flashcards
A

When organisms live in close nutritional relationships, required by one or both members

  • Mutualism: both members benefit
  • Commensalism: one member benefits but the other member is not harmed
  • Parasitism: Parasite is dependent and benefits but host is harmed
24
Q

What does it mean when organisms are non symbiotic? What are different types of non symbiotic relationships?

Study These Flashcards
A

Organisms are free living relationships are not required for survival

  • Synergism: members cooperate and share nutrients
  • Antagonism: some members are inhibited or destroyed by others
25
Which chemicals are usually required as cofactors for enzymes?
Trace elements (iron, copper, zinc, molybdenum)
26
Organisms that CANNOT grow without oxygen are known as _____ What does their oxygen growth look like?
Obligate aerobes Growth at the top due to places with high concentrations of oxygen
27
Organisms that utilize oxygen but can also grow without it are known as ______. What does their oxygen growth look like?
Facultative aerobes Growth best where oxygen is present, but can still grow throughout the tube
28
Organisms that require only a small amount of oxygen are known as ____ What does their oxygen growth look like?
Microaerophiles Growth where a low concentration of oxygen is found
29
Organisms that CANNOT SURVIVE in oxygen due to lacking enzymes that detoxify oxygen are known as ______ What does their oxygen growth look like?
Obligate anaerobes Growth only where there is no oxygen (like the bottom)
30
Organisms that does not utilize oxygen but can survive and grow in its presence are known as _____ What does their oxygen growth look like?
Aerotolerant anaerobes Growth evenly distributed throughout the tube
31
What does catalase do?
neutralizes hydrogen peroxide
32
Culture media that is used to prepare microbial growth in liquid and solid form respectively are known as ______ and ______
nutrient broth nutrient agar
33
The type of media where the exact chemical composition is known is ________
Chemically defined media
34
Which type of media is used for cultivating anaerobic bacteria?
Reducing media
35
Which type of media suppresses unwanted microbes and encourages desired microbes and contain inhibitors to suppress growth?
Selective media
36
Which type of media allows distinguishing of colonies of different microbes on the same plate?
Differential media
37
Which organisms need CO2 at higher concentrations than atmospheric CO2?
Capnophiles
38
What are 3 ways you can preserve bacterial cultures?
- Deep-freezing: -50 to -95 degrees celsius - Lyophilization (freeze-drying): frozen (-54 to -72 C) and dehydrated in a vacuum - refrigeration on agar slants
39
When a single cell divides into two identical daughter cells this is known as _____
Binary fission
40
The time it takes for a microbe to divide and replicate itself (usually 20 mins to 24 hours) is known as _____
Generation time
41
*How is generation time determined?
The total number of cells equals 2 generations
42
How do you calculate the number of bacteria produced after a certain time period?
Initial population x 2 to the power of # of generations eg. IP: 2, # gen: 3 = 2 x 2^3 = 16
43
What are the advantages and disadvantages of the plate count method?
Advantages: - counts viable cells - can target specific cells within a mixed population - can detect a wide range of microbial densities even in low cell count samples Disadvantages: - does not count dead cells - difficult to distinguish between bacterial colonies and debris - Time consuming; results could take weeks
44
What are the four phases of growth and what happens in each phase?
1. Lag phase: bacteria begin growing but slowly 2. Log/ exponential phase: bacteria starts growing fast and rapidly 3. Stationary phase: the rate of cell growth equals the rate of cell death 4. Death phase: more death than growth
45
What are the 4 direct methods of measuring microbial growth?
- Plate count - Filtration - Most probable number (MPN) method - Direct microscopic count
46
Describe the plate count method
- Count colonies on plates that have 30-300 colonies - Dilute original inoculum via serial dilution to ensure the right number of colonies - counts are then performed on bacteria mixed into a dish with agar (pour plate method) or spread on the surface of a plate (spread plate method)
47
Describe the filtration method
- Solution is passed through a filter that collects bacteria - Filter is transferred to a petri dish and grows as colonies on the surface
48
Describe the direct microscopic count method
- The volume of a bacterial suspension is placed on a slide - The avg number of bacteria per viewing field is calculated - Uses a special Petroff- Hausser cell counter bacteria/ml = # of cells counted/ volume of area counted
49
What are the indirect methods of estimating the number of bacteria?
- Turbidity - Metabolic activity - Dry weight
50
How does the turbidity method estimate the number of bacteria?
The degree of cloudiness measured with a spectrophotometer shows the relative population size

Microbiology :O (16 decks)

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