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Microbiology > Chapter 6 Microbial Growth > Flashcards

Chapter 6 Microbial Growth Flashcards

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Biology 101 flashcards
1
Q

what does microbial growth refer to?

A

the number of cells / nothing to do with the individual size

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2
Q

what are colonies in term of microbes?

A

groups of cells large enough to be seen without a microscope

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3
Q

what does the population refer to?

A

billions of cells of the same species

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4
Q

how are growth temperature ranges defined?

A

every microbe grows best in certain temperatures. we categorize them based on their
- minimum growth temperature
- optimum growth temperature
- maximum growth temperature

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5
Q

what are the different classes of microbes that like to grow at different temps?

A

psychrophiles: cold-loving
mesophiles: moderate-temperature loving
thermophiles: heat-loving

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6
Q

what temperature do psychrophiles grow in vs their optimum growth temp?

A

0° Celsius
15° Celsius

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7
Q

what temperature do psychrotrophs grow in vs their optimum growth temp?

A

0° Celsius
20-30° Celsius

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8
Q

what temperature is mesophiles’ optimum growth temp?

A

25-45° Celsius

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9
Q

what temperature is thermophiles optimum growth temp? What is the lowest temp they can grow in?

A

Optimum growth temperature: 50-60°C
Cannot grow below: 45°C

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10
Q

what is hyperthermophiles optimum growth temp?

A

Optimum growth temperature: 80°C or higher

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11
Q

what class of microbes are most likely to contain microorganisms that are human pathogens?

A

Because mesophiles can grow in room temperature and body temperature, they are MOST likely to be pathogens and cause spoilage of food or disease

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12
Q

which microbe class is the most common?

A

mesophiles

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13
Q

other than mesophiles, what other organisms can cause human harm?

A

pyschrotrophs can cause low temp food spoilage

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14
Q

what is the danger range of temp that bacteria are rapidly growing and may produce toxins?

A

15 - 50°C

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15
Q

what is the optimum pH range for bacteria?

A

6.5 - 7.5

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16
Q

what is the optimum pH range for Molds and Yeast?

A

5 - 6

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17
Q

what do acidophiles refer to and what is their optimum pH?

A

acid-lover
2 or below

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18
Q

Describe the process of plasmolysis

A

Hypertonic environment means there are more solutes outside the cell walls, than there are inside. Osmotic pressure causes fluid to escape out of the cell wall. this process is what makes up plasmolysis (similar process to crenation of blood cell)

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19
Q

what does halophiles refer to?

A

salt-loving; they REQUIRE salt for growth

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20
Q

what is the difference between facultative halophiles and extreme halophiles?

A

facultative halophiles: can tolerate 2% salt - at most 15%
extreme halophiles: require 30% salt for growth

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21
Q

why do cells not normally survive under salty conditions?

A

salty conditions means more solutes outside of the cell than inside (hypertonic solution) when in a hypertonic solution, the fluid inside of cells leaves outside of the cell wall due to osmotic pressure and the cell goes under plasmolysis and ruptures

22
Q

what nutrients are needed for major cellular functions?

A

carbon
nitrogen
sulfur
phosphorus
oxygen
trace elements

23
Q

what does the nutrient: carbon, help function?

A

makes up the structural backbone of living matter

24
Q

what does the nutrient: nitrogen, help function?

A

DNA and RNA production
protein synthesis

25
Q

what does the nutrient: phosphorus, help function?

A

Nucleic acids
synthesis of ATP
synthesis of cell membrane

26
Q

what does the nutrient: sulfur, help function?

A

sulfur containing amino acids (which are needed to build specific proteins)
vitamins

27
Q

what do trace elements help function? (iron, copper, zinc, molybdenum)

A

cofactors for enzyme function

28
Q

how can oxygen in the atmosphere be toxic?

A

when oxygen accepts excess electrons, it becomes a radical
oxygen radicals can interfere with other (metabolic functions?)

29
Q

what are two forms of oxygen radicals?

A

superoxide anions (radicals)
peroxide anion (hydrogen peroxide)

30
Q

what is the enzyme that detoxifies superoxide anions?

A

superoxide dismutase (SOD): neutralizes radicals to O2 and H2O2

31
Q

what happens when you pour hydrogen peroxide on a cut? why?

A

catalase found in our body break down hydrogen peroxide into oxygen and water which looks like foam when hydrogen peroxide is poured onto a cut in order to NEUTRALIZE TOXIC OXYGEN IMPORTANT

32
Q

what are two enzyme that detoxifies peroxide anion?

A

catalase: creates water and O2
peroxidase: creates two water molecules

33
Q

How are superoxide anions formed?

A

in small amounts during normal respiration

34
Q

what is another name for peroxide anion?

A

hydrogen peroxide

35
Q

know examples of organic growth factors

A
36
Q

describe obligate aerobes

A

NEED oxygen to survive; will always produce catalase and SOD

37
Q

describe facultative anaerobes

A

can grow in oxygen and without; will have catalase and SOD

38
Q

describe obligate anaerobes

A

can only grow in an environment without oxygen; lack enzymes because they will never form toxic oxygen radicals

39
Q

describe aerotolerant anaerobes

A

can tolerate oxygen presence but grow in anaerobic conditions; presence of SOD

40
Q

describe microaerophiles

A

only grow in aerobic conditions BUT in small amounts

41
Q

describe how we usually measure bacterial growth

A

generation time: how long it takes for one cell to divide into two cells

42
Q

A short generation will cause what to happen

A

more microbes to grow faster

43
Q

A longer generation time will cause what to happen?

A

less microbes to grow

44
Q

what are the four phases of bacterial growth?

A

lag phase
log phase
stationary phase
death phase

45
Q

describe lag phase

A

there is little or no cell division (cell is figuring out its environment)

46
Q

describe log phase

A

exponential growth phase
acclimated to environment

47
Q

describe stationary phase

A

of new cells is equal to # of dead cells
use up nutrients

48
Q

describe death phase

A

of deaths is more than # of new cells

49
Q

what does drinking salt water when sick cause to happen?

A

drinking salt water creates a hypertonic solution which causes bacteria plasmolysis

50
Q

A longer generation time will cause what to happen?

A

less microbes to grow

Microbiology (23 decks)

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