MICROBIAL METABOLISM

Question 1

what is metabolism

Answer 1

means biochemical reactions that occurs in a cell

Question 2

what are the classifications of metabolic reactions

Answer 2

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

Question 3

define an enzyme

Answer 3

is a cellular catalyst

Question 4

what are oxidoreductases

Answer 4

involved in oxidation or reduction electron transfer reaxion

Question 5

what are transferases

Answer 5

transfer of amino groups

Question 6

what are hydrolases

Answer 6

cleavage of bonds with addition of water(hydrolysis)

Question 7

what are lyases

Answer 7

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

Question 8

what are ligases

Answer 8

joining reactions, using energy from ATP

Question 9

What influences biochemical reactions in enzymes

Answer 9

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

Question 10

explain the process of energy production

Answer 10

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.

Question 11

what is fermentation

Answer 11

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

Question 12

what is microbial growth

Answer 12

refers to an increase in the number of microbes

Question 13

factors that influence microbial growth

Answer 13

1. nutrition
2. temperature
3. PH
4. osmotic pressure

Question 14

define culture

Answer 14

microbes that grow and multiply in or on a culture medium

Question 15

what are the requirements of culture

Answer 15

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

Question 16

Define culture

Answer 16

Microbes that grow and multiply in or on a culture

Question 17

explain the 2 phases of growth media

Answer 17

~ 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

Question 18

Explain 3 unique properties of agar

Answer 18

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

Question 19

mention 4 general categories of media

Answer 19

1. Enrichment
2. Supportive
3. Selective
4. Differential

Question 20

What is the purpose of selective media

Answer 20

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

Question 21

How is selective media achieved

Answer 21

By incorporatig specific inhibitory substances ito the medium.

Question 22

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

Answer 22

Selective media

Question 23

Explain the use of briliant green agar and bismuth sulfite agar

Answer 23

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

Question 24

what is the use of differential media

Answer 24

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

Question 25

Difference between selective media and differential media.

Answer 25

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.

Question 26

using examples only differentiate selective media and differential media

Answer 26

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.

Question 27

What is the purpose of differential media

Answer 27

It is used to distinguish colonies of a desired organisms.

Question 28

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

Answer 28

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

Question 29

Similarities between selective and differential media.

Answer 29

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

Question 30

Explain use of enrichment culture media

Answer 30

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

Question 31

why is chemically defined media

Answer 31

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

Question 32

What chemicals are used in chemically defined media

Answer 32

acids, vitamins and bulding blocks required by microbe.

Question 33

Explain complex media.

Answer 33

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).

Question 34

Explain anaerobic growth media

Answer 34

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

Question 35

what are special culture techniques

Answer 35

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

Question 36

Why do we use special culture techniques

Answer 36

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

Question 37

Examples of special culture techniques microbes

Answer 37

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

Question 38

Define pure culture

Answer 38

Contains a single microbial species

Question 39

How is pure culture obtained

Answer 39

Individual organisms must be isolated

Question 40

What common method of isolation is used to achieve pure culture

Answer 40

Streak plate method

Question 41

What is generation time?

Answer 41

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

Question 42

How does generation time vary among different bacteria?

Answer 42

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.

Question 43

What happens during the lag phase?

Answer 43

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.

Question 44

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

Answer 44

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.

Question 45

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

Answer 45

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).

Question 46

What happens during the death phase?

Answer 46

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.

Question 47

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

Answer 47

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.