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mmi 133 > Bacterial Growth > Flashcards

Bacterial Growth Flashcards

1
Q

What is the Gram morphology of Listeria monocytogenes?

A

G+ bacilli

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2
Q

What are the four physical factors that affect bacterial growth?

A
  • Temperature
  • pH
  • Osmotic pressure
  • Gas
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3
Q

What is the difference between psychrotrophs and mesophiles?

A

Psychrotrophs can withstand 20-30°C meanwhile mesophiles can withstand 25-45°C

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4
Q

The range of pH which human pathogens can withstand is:

A

5-8

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5
Q

Obligate halophiles require ____ salt concentrations

A

high

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6
Q

Facultative halophiles tolerate salt concentration within the range of:

A

2-15%

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7
Q

What is the main virulence factor of L. monocytogenes?

A

Listeriolysin breaks open vacuoles containing bacteria (ex: macrophages), releasing bacteria into the cytoplasm & preventing destruction by lysosomes. This allows the bacteria to access the cell’s actin.

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8
Q

Obligate aerobes only grow ___ the presence of oxygen

A

with

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9
Q

Two chemical factors that affect bacterial growth are:

A
  • Sources of C, N, O, S, P + trace elements

- Sources of organic growth factors

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10
Q

An environmental factor that affects bacterial growth is:

A

Evasive defense mechanisms that require antibiotics to penetrate the membrane in order to be effective

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11
Q

L. monocytogenes grows best in 20-30ºC, which means it is a _____________.

A

psychrotroph

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12
Q

What are some reasons why L. monocytogenes is such a good food pathogen?

A
  • Can grow in wide temp (3-42ºC) & pH range.
  • Can survive in freezer temperatures.
  • Can grow in high concentrations of NaCl (food preservation agent).
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13
Q

What is L. monocytogenes’ normal habitat?

A

Grasses & soil in the environment.

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14
Q

How does L. monocytogenes make its way into our food?

A

Food that has been contaminated with animal feces.

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15
Q

What are some symptoms of listeriosis from L. monocytogenes in animals?

A

CNS infection (“circling disease”) & septic abortion.

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16
Q

Define generation time

A

The time for one bacterium to divide into two

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17
Q

What are the four phases of bacterial growth kinetics

A

Lag phase, log phase, stationary phase and death phase

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18
Q

Describe the lag phase

A

There is minimal/no cell division

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19
Q

Describe the log phase:

A

The cell begins to divide; most metabolically active phase

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20
Q

Describe the stationary phase:

A

Cell division slows down

21
Q

When culturing bacteria, a ___ ___ ___ is required, which can be solid, semi-solid or liquid

A

sterile nutrient material

22
Q

Biofilms are:

A

Dynamic communities of bacteria which antibiotics are ineffective towards

23
Q

The purpose of differential media when culturing bacteria is:

A

To identify/narrow down similar bacteria

24
Q

Define anabolism

A

A chemical reaction that form complex organic compounds and require energy

25
Q

Hemolysis is:

A

The breakdown of blood cells

26
Q

The three results of hemolysis and their colors are:

A

Alpha [green] (partial breakdown of RBC), Beta [yellow] (total breakdown of RBC), Gamma [purple] (no breakdown of RBC)

27
Q

When culturing bacteria, a ___ ___ ___ is required, which can be solid, semi-solid or liquid

A

sterile nutrient material

28
Q

How does L. monocytogenes evade WBCs and move from cell-to-cell?

A

It produces the ActA protein, which binds to the actin cytoskeleton & builds a tail that can propel the bacteria from one cell to another.

29
Q

What are the 3 main symptoms of listeriosis in humans?

A

Meningitis, encephalitis & septicemia.

30
Q

An incubation period is the time between ________ to a bacteria and ________ appearing in a person.

A

exposure, symptoms

31
Q

What is the incubation period of L. monocytogenes?

A

2 months.

32
Q

Which 3 groups of people are at increased risk for serious infection by L. monocytogenes?

A

The elderly, immunocompromised & pregnant women.

33
Q

Why is infection by L. monocytogenes specifically dangerous for pregnant women?

A

They have lower immune system tolerance because of their baby, but if the fetus is infected with the bacteria, it will be septically aborted.

34
Q

How is L. monocytogenes transmitted?

A

Fecal-oral.

35
Q

How do you treat listeriosis?

A

Antibiotics but you must diagnose the infection in time!

36
Q

Define metabolism

A

The sum of all chemical reactions within an organism

37
Q

Define catabolism

A

A chemical reaction that breaks down organic compounds and releases energy

38
Q

Define anabolism

A

A chemical reaction that form complex organic compounds and require energy

39
Q

Reaction rates are temp. dependent but extreme high temp.s may lead to:

A

Denaturing of proteins

40
Q

Enzymes ____ activation energy and ____ reaction rates

A

lower, increase

41
Q

Do enzymes get used up during the reaction?

A

No

42
Q

Factors that can affect enzyme performance are:

A
  • Temp
  • pH
  • Saturation
  • Salt concentration
  • Inhibitors
43
Q

What are the two types of cellular respiration?

A

Aerobic (presence of O2) and anaerobic (absence of O2).

44
Q

Aerobic cellular respiration produces ____ ATP and results in ______ growth than anaerobic.

A

more, faster

45
Q

An ________ ______ needs O2 to grow and an ________ ________ can only grow in the absence of O2.

A

obligate aerobe, obligate anaerobe

46
Q

___________ _________ can grow with or without O2.

A

Facultative anaerobes.

47
Q

Fermentation is a _______ breakdown of nutrients.

A

partial

48
Q

What is the main source of fuel for energy production?

A

Glucose (or other carbs)

49
Q

What are some alternate biomolecules as sources of energy in the body?

A

Lipids, proteins

mmi 133 (26 decks)

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