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Micro 1 - Justin > Bacterial Growth and Metabolism > Flashcards

Bacterial Growth and Metabolism Flashcards

- Know conditions that affect bacterial growth rate - Describe a typical bacterial growth curve - Define siderophore and bacterial biofilm - Distinguish aerobic from anaerobic growth - Define normal flora and recall benefits and hazards of colonization - Recall principle of normal flora of various tissues - Define Key terms associated with infectious disease

1
Q

How do bacteria replicate

A

binary fission

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2
Q

In binary fission, what happens in the cell?

A
  • disruption of peptidoglycan cell wall
  • replication of bacterial genome
  • segregation to form daughter cells
  • establishment of new ends (septa) to cytoplasmic (outer) membrane
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3
Q

Growth rate of bacteria depends on?

A
  • nutrients available
  • pH
  • salinity (salt content)
  • temperature
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4
Q

Prototroph can ____________?

A

synthesize all essential metabolites

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5
Q

What do auxotroph need for cell survival?

A

need to obtain essential metabolites from the environment. (cannot synthesize their own because they have acquired mutations in synthesizing essential metabolites.

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6
Q

Normally, Acidic or basic pH inhibits bacterial growth?

A

Acidic, low pH in certain tissues and organs prevent growth

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7
Q

What bacteria can overcome the acidic environment?

How?

A

Helicobacter pylori, H. pylori
secrete urease that converts urea to ammonia and bicarbonate –> establish infection in the gastric tract to cause ulcers

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8
Q

High or low salt concentration in the environment inhibits growth?

A

High! there are some that are resistant too.

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9
Q

Human pathogens are classified as ?

A

meophiles, because they grow optimally between 30 -37 degree Celsius.

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10
Q

What nutrient impacts the rate of cell division?

A

Iron, it is important to growth and virulence (capability to cause disease)

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11
Q

How does the human body sequester free iron in the blood?

A

by transferin and lactoferrin, iron-binding proteins –> significant defense against infection

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12
Q

What must happen for bacteria to colonize the host?

A

counter the iron limitations

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13
Q

How do bacteria counter iron limitations?

A

secreting siderophores which chelate irons and then ACTIVELY transport into the cell

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14
Q

How are bacteria measured in liquid culture?

A

Growing aliquot(portion of total ) of the culture on agar medium as the aliquots are taken at various times after broth inoculation.

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15
Q

What is an alternative way to measure growth of bacteria ?

A

Measure turbidity (cloudiness) of the liquid culture over time. As bacteria multiply, they cloud the broth and measured using spectrophotometer.

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16
Q

Why is there no growth immediately after inoculation of the liquid culture?

A

LAG PHASE

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17
Q

What happens in lag phase?

A

bacteria are adapting to new nutrient environment, reprogramming gene expression.

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18
Q

Bacteria replication is constant and at an optimal doubling times in what phase

A

Exponential Phase

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19
Q

What happens in the exponential phase in the cell?

A

maximal DNA and protein synthesis

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20
Q

What phase is most sensitive to antibiotic therapy?

A

exponential (logarithmic phase)

21
Q

When is a good time to gram stain organism?

A

exponential phase

22
Q

What is a consequence of exponential growth?

A

depletion of nutrients and accumulation of wastes

23
Q

Describe the stationary phase

A

metabolism is reduced, rate of cell division is equal to the rate of cell death. Thus, no net increase in the number of viable cells.

24
Q

When do gram positive bacteria initiate sporulation?

A

stationary phase

25
Q

Describe the decline (death) phase?

A

rate of cell death exceeds the rate of cell division due to depletion of nutrients and accumulation of waste

26
Q

80% of infections results from bacteria organizing to form ?

A

biofilm

27
Q

What is biofilm?

A

a protective carbohydrate matrix, formed by events of motility and adhesion of bacteria

28
Q

Why is biofilm important ?

A

they are a source of recurrent infections and treatment failures. It impairs antibiotic access, anti-phagocytic, and requires removal of the infective implant b/c of its adherent nature.

29
Q

Where can biofilm be found?

A

dental plaques, in-dwelling catheters, and contact lens

30
Q

What is the purpose of metabolism?

A

To provide energy and building blocks for cell survival and division.

31
Q

What kind of bacteria can use oxygen?

A

facultative anaerobes and aerobic bacteria

32
Q

How many ATP can be produced?

A

34

33
Q

In absent of oxygen, what can occur in facultative anaerobes?

A

anaerobic respiration: oxidation of an organic or inorganic compound other than oxygen.

34
Q

Strict (obligate) anaerobes use

A

fermentation to generate energy and metabolite

35
Q

During fermentation, pyruvate –>

A

organic compounds like acetic acid, butyric acid, lactic acid, CO2. Inefficient way to generate energy

36
Q

Which grows slower: anaerobic growth or aerobic growth?

A

anaerobic growth

37
Q

Consequence of respiration?

A

produce H2O2 and superoxides

38
Q

Strict (obligate) aerobes produce 3 enzymes

A

superoxide dismutase, catalase, peroxidase

39
Q

Facultative anaerobes may lack which of the 3 enzymes?

A

catalase

40
Q

Why is O2 toxic to strict (obligate) anaerobes?

A

Lack superoxide dismutase, thus accumulation of superoxide anions.

41
Q

Why do bacteria must synthesize folic acid rather than use it from the environment?

A

B/c it is a source of nucleotides and methionine.

42
Q

What can be a key aspect of pathogenesis and spread of bacteria?

A

intracellular survival

43
Q

What are obligate intracellular pathogens?

A

Bacteria that can only replicate inside of host cells.

44
Q

What are some features of obligate intracellular pathogens?

A

they are dependent on the host cell for nucleotide cofactors and ATP

45
Q

What are some benefits of normal flora?

A

inhibit growth of new bacteria by several ways: production of FA in the skin, toxins and waste in the gut, occupy space in the gut, produce acid in the vaginal area

46
Q

What are some benefits of gut normal flora?

A

produce toxins and waste that deter other bacteria

47
Q

How can normal flora be bad?

A

When they spread to a normally sterile site, overgrow their niche, become immunocompromised

(internal tissue and blood are normally sterile sites)

48
Q

What are bacteria in the blood called?

A

bacteremia

Micro 1 - Justin (5 decks)

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