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Microbiology 1 > MICROBIAL METABOLISM > Flashcards

MICROBIAL METABOLISM Flashcards

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1
Q

what is metabolism

A

means biochemical reactions that occurs in a cell

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2
Q

what are the classifications of metabolic reactions

A
  1. catabolism describes breakdown of large molecules to release energy
  2. anabolism describes reactions involved in the synthesis of macromolecules
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3
Q

define an enzyme

A

is a cellular catalyst

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4
Q

what are oxidoreductases

A

involved in oxidation or reduction electron transfer reaxion

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5
Q

what are transferases

A

transfer of amino groups

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6
Q

what are hydrolases

A

cleavage of bonds with addition of water(hydrolysis)

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7
Q

what are lyases

A

cleavage of C-C, C-O OR C-N to form double bond

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8
Q

what are ligases

A

joining reactions, using energy from ATP

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9
Q

What influences biochemical reactions in enzymes

A
  1. effect of inhibitors
  2. changes in the amount of enzyme or substrate
  3. availability of any necessary cofactors
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10
Q

explain the process of energy production

A

ATP as the cellular energy storage unit, can be formed during respiration or fermentation.
both contain glycolysis pathway which produces ATP, the electron carrier molecule NADH and pyruvate from glucose.

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11
Q

what is fermentation

A

a microbial process by which an organic substrate is brocken down without the involvement of oxygen

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12
Q

what is microbial growth

A

refers to an increase in the number of microbes

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13
Q

factors that influence microbial growth

A
  1. nutrition
  2. temperature
  3. PH
  4. osmotic pressure
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14
Q

define culture

A

microbes that grow and multiply in or on a culture medium

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15
Q

what are the requirements of culture

A
  1. must be sterile
  2. contain appropriate nutrients
  3. must be incubated at appropriate temperature
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16
Q

Define culture

A

Microbes that grow and multiply in or on a culture

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17
Q

explain the 2 phases of growth media

A

~ growth media are used in either liquid (broth) or solid (agar)
1. in broth media nutrients are dissolved in water and bacterial growth is indicated by a change in the broth’s appearance from clear to turbid
2. Solid media, Nutriet material that contains a solidifying agent added to nutrients and water

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18
Q

Explain 3 unique properties of agar

A
  1. Melts above 95 degree celcius
  2. Once melted, does not solidify until it reaches 40 degree celcius.
  3. Cannot be degreeded by most bacteria
  4. Polysaccharide made by red algae
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19
Q

mention 4 general categories of media

A
  1. Enrichment
  2. Supportive
  3. Selective
  4. Differential
20
Q

What is the purpose of selective media

A

Selective media allow the growth of chosen or desired microorganisms while inhibiting the growth of others.

21
Q

How is selective media achieved

A

By incorporatig specific inhibitory substances ito the medium.

22
Q

What contains one or more agents that are inhibitory to all organisms except those being sought

A

Selective media

23
Q

Explain the use of briliant green agar and bismuth sulfite agar

A
  1. Briliant green agar inhibits gram positive bacteria.
  2. Bismuth sulfite agar isolate salmonella typhi
24
Q

what is the use of differential media

A

It is used in microbiology to differentiate closely related microorganisms based on their biochemical properties.

25
Q

Difference between selective media and differential media.

A

Selective media are designed to promote the growth of specific microorganisms while inhibiting the growth of undesired ones WHILE Differential media do not inhibit any growth, but they contain indicators that help differentiate between types of microorganisms based on their metabolic activities.

26
Q

using examples only differentiate selective media and differential media

A

SELECTIVE MEDIA:
1. Eosin Methylene Blue (EMB): Contains methylene blue, which is toxic to Gram-positive bacteria, allowing only the growth of Gram-negative bacteria.
2. YM (Yeast and Mold): Has a low pH, deterring bacterial growth.
3. MacConkey Agar: Selective for Gram-negative bacteria.
4. Hektoen Enteric Agar (HE): Selective for Gram-negative bacteria.
5. Mannitol Salt Agar (MSA): Selective for Gram-positive bacteria and differential for mannitol utilization.

27
Q

What is the purpose of differential media

A

It is used to distinguish colonies of a desired organisms.

28
Q

Blood agar is an example of differential medial. what is differential media used for?

A

Blood agar is used to distinguish bacteria that destroy red blood cells (hemolysis)

29
Q

Similarities between selective and differential media.

A

They are both used to distinguish colonies of a desired organism.

30
Q

Explain use of enrichment culture media

A

Contain specific nutriets required for the growth of particular bacterial pathogens.

31
Q

why is chemically defined media

A

Nutrient material whose exact chemical chemical composition id known. Precise and known amounts of individual chemical components, such as amino acids, vitamins, salts, and other nutrients

32
Q

What chemicals are used in chemically defined media

A

acids, vitamins and bulding blocks required by microbe.

33
Q

Explain complex media.

A

Material whose exact chemical composition is not known. (Complex media contain a variety of undefined components such as yeast extract, peptones, and animal or plant extracts).

34
Q

Explain anaerobic growth media

A

it is use dto grow anaerobes that might be killed by oxygen.

35
Q

what are special culture techniques

A

These are methods used to gtow bacteria that have unusual growth requirements.

36
Q

Why do we use special culture techniques

A

Because some bacteria are challenging to cultivate using standard laboratory media.(scientists use specialized texhniques to support their growth)

37
Q

Examples of special culture techniques microbes

A
  1. Mycobacterium leprae (Leprosy): Grown in armadillos
  2. Treponema pallidum (syphilis): Grown in rabbit testicles
  3. Obligate intracellular bacteria (Rickettsias and chlamydias: Only grown in host cells
38
Q

Define pure culture

A

Contains a single microbial species

39
Q

How is pure culture obtained

A

Individual organisms must be isolated

40
Q

What common method of isolation is used to achieve pure culture

A

Streak plate method

41
Q

What is generation time?

A

The time required for a single cell to divide and the population to double in number.

42
Q

How does generation time vary among different bacteria?

A

Generation time varies significantly. E. coli divides very quickly, every 20 minutes, while most bacteria take 1 to 3 hours. Some bacteria can take over 24 hours to divide.

43
Q

What happens during the lag phase?

A

During the lag phase, bacteria are adjusting to a new environment. They are synthesizing enzymes and other molecules needed for growth and reproduction. There is little to no cell division, but there is increased metabolic activity as the cells prepare for the rapid growth phase to come.

44
Q

Why is the log phase (exponential phase) the most rapid growth period?

A

During the log phase, cell division occurs rapidly, causing the population to increase exponentially. The number of cells dividing is greater than the number dying, and the cells are highly metabolically active. However, this rapid growth cannot be sustained indefinitely.

45
Q

What factors can slow down microbial growth during the stationary phase?

A
  1. Accumulation of toxic waste products from the bacteria themselves.
  2. The growth medium becoming acidic due to bacterial activity.
  3. Depletion of nutrients in the medium.
  4. Limited oxygen supply (for aerobic bacteria).
46
Q

What happens during the death phase?

A

During the death phase, the number of viable cells starts to decline rapidly. More cells are dying than dividing, and the overall population size decreases exponentially. Eventually, most cells will die, although some may remain alive for a longer period.

47
Q

What are three methods used to determine the number of bacterial cells in a diagnostic lab?

A
  1. Direct counting under a microscope: This method involves physically counting individual cells using a specialized microscope.
  2. Direct plate count: This method involves diluting a sample and plating it on a growth medium. The colonies that grow represent individual bacteria, and the number of colonies can be counted to estimate the original cell number.
  3. Density measurement: This method uses instruments to measure the turbidity or density of a bacterial culture. Since cell density is related to cell number, this can be used as an indirect estimate of cell population.

Microbiology 1 (27 decks)

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