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Microbiology > Ch 6 Microbial Growth > Flashcards

Ch 6 Microbial Growth Flashcards

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Biology 101 flashcards
1
Q

what are psychrophiles

A

cold-loving microbes, grow at coldest temps, can grow below freezing (below 0C)optimum=12-15 C

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2
Q

what are mesophiles

A

moderate-temperature loving, optimum=37C

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3
Q

what are psychrotrophs

A

cant grow below 0C unlike psychrophiles, optimum=

22C

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4
Q

these 2 bacterial groups cannot cause infection bc they only survive at temperatures below body temp

A

psychophiles and psychrotrophs

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5
Q

all bacteria that cause infections are in this temp based group

A

mesophiles

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6
Q

this group of microbes is common in low temp food spoilage bc grows well in refrigerator temp

A

psychrotrophs

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7
Q

what are thermophiles

A

capable of growth at high temps, (opt 62C), seen in hot springs

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8
Q

what are hyperthermophiles

A

archaea opt- 80+C, seen in deep sea events that are under pressure or hot springs

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9
Q

importance of heating and cooling in food preservation

A

heat to a certain point to kill most microbes, cool to prevent more growth, in between is “danger zone”(15-52C)

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10
Q

why small containers of food are better than large for refridgeration

A

temp drops faster, goes thro danger zone quicker

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11
Q

optimum pH range for most bacteria

A

6.5-7.5

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12
Q

difference between autotrophs and heterotrophs in terms of C

A

autotrophs get CO2 from atmosphere

heterotrophs from other organisms

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13
Q

why bacteria need Carbon

A

C is structural backbone of living matter, needed for organic compounds that make up cell

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14
Q

why microbes need Nitrogen

A

synthesis of protein (form the amino group of amino acids in proteins), DNA/RNA, ATP

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15
Q

why microbes need sulfur

A

synthesize amino acids (therefore important in protein synthesis), makes vitamins such as thiamine and biotin

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16
Q

why microbes need phosphorus

A

essentilal for phospholipids of cell membranes, ATP, and synthesis of nucleotides (sugar-phosphate backbone of DNA)

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17
Q

these 2 trace elements are needed as cofactors for enzyme functioning

A

zinc, molybdenum , copper, and iron

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18
Q

why O2 is toxic for many organisms

A

in first 2 billion years on earth v little molecular oxygen, O2 is a powerful oxidizer (strips e- from others) causing metabolic problems

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19
Q

what bacteria have evolved to produce to reduce toxic effects of O2

A

enzymes Catalase and superoxide dismutase

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20
Q

catalase v. superoxide dismutase

A

Catalase neutralizes H2O2 (2H2O2–> O2 +2H2O)
superoxide dismutase=
2O2- (superradical) + 2H+–>O2 + H2O2
converts superradical into molecular O2

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21
Q

what are obligate aerobes

A

require O2

22
Q

what are facultative anaerobes

A

prefer O2 but can grow without it (switch to anaerobic resp) but efficiency decreases

23
Q

what are obligate anaerobes

A

only use anaerobic respiration

24
Q

how catalase and superoxide dismutase work in conjunction

A

SOD converts superradical O2- into O2 producing H2O2 as a byproduct
catalase neutralizes this H2O2

25
Q

what are aerotolerant anaerobes

A

only anaerobic but continue even in presence of O2 (tolerate it, but don’t use it)

26
Q

difference between culturing obligate anaerobes and aerotoleant anaerobes

A

obligate need special techniques so no O2 is present , aerotolerant dont bc they can tolerate the presence of O2

27
Q

many aerotolerant bacteria produce

A

lactic acid via fermentation

28
Q

what are micoaerophiles

A

aerobic, cant tolerate too much or too little O2 (grow in O2 concentrations lower than that of air

29
Q

what makes up the slime portion (matrix in which bacteria reside) of biofilms

A

primarily polysaccharides and some DNA and proteins

30
Q

why quorum sensing important

A

allows bacteria to coordinate their activity and group together into communities
they also share nutrients, and are sheltered from environment, may also transfer genetic info between each other (conjugation)

31
Q

biofilms are not just slime layers they are

A

biological systems

32
Q

how a biofilm begins

A

a planktonic, free-swimming bacteria attaches to a surface

33
Q

how biofilms avoid lack of nutrients at lower depths and buildup of toxic waste

A

form pillar-like structures with channels thro which water can carry incoming nutrients and outgoing wastes. (like a circulatory system)

34
Q

how a biofilm extends

A

individual planktonic bacteria leave and move to new location

35
Q

situations in which biofilms are importants

A

in rumen of ruminants to breakdown cellulose, also essential in sewage treatment systems

36
Q

__% of human bacterial infections involve biofilms, they are (more or less) resistant to antibiotics

A

70%, more resistant

37
Q

most nosocomial infections are caused by

A

biofilms on catheters

38
Q

our latest approach to preventing biofilm formation is

A

incorporating antibiotics into surfaces in which biofilms might form. or finding a way to block quorum sensing.

39
Q

difference between selective and differential media (medium= subs used to grow bacteria)

A

selective- supress growth of unwanted bacteria, encourage growth of desired
differential- allow distinguishing of types of bacteria

40
Q

a pH sensitive indicator is an example of what kind of medium

A

differential

41
Q

what are the 4 phases of the bacterial growth curve

A

Lag, Log, stationary, and death phase

42
Q

bcterial growth curve: period of little- no cell division, intense activity preparing for pop growth (like replicating DNA)

A

1)Lag phase

43
Q

bacterila growth curve: period of growth (logarithmic or exponential), generation time consistent

A

2) Log phase

44
Q

bacterial growth curve: growth rate slows, number of deaths= number of new cells (equilibrium)

A

3) stationary phase

45
Q

bacterial growth curve: number of deaths exceed the number of new cells, population decreases at logarithmic rate

A

4) death phase

46
Q

how to use a serial dillution to count bacteria

A

take an innoculation dilute into inceasing dilutions (1:10, 1:100, 1:1000, etc.) until # of CFUs is reasonable to count

47
Q

how to calculate # of cells after counting one of its serial dilutions

A

of cells x dillution factor

48
Q

optimal pH range for molds and yeasts

A

5-6

49
Q

complex media v. chemically defined media

A

chem defined: exact contents are known, good for growing bacteria w specific requirements
complex: unknown contents, made of nutrients from extracts from yeasts, meat etc. (ex: peptone (partially digested proteins, beef extract, etc.)

50
Q

a basic microbiology lab would be what biosafety level

A

1

51
Q

our lab (one that involves sterile technique) is which biosafety level

A

2

Microbiology (21 decks)

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