Assessment #3

Question 1

culture medium

Answer 1

a nutrient material prepared for the growth of microorganisms in a laboratory

Question 2

inoculum

Answer 2

microbes that are introduced into a culture medium

Question 3

culture

Answer 3

the microbes that grow and multiply in or on a culture medium

Question 4

examples of criteria that a culture medium must meet

Answer 4

• right nutrients
• sufficient moisture
• proper pH
• suitable level of oxygen
• sterile
• proper temperature

Question 5

agar

Answer 5

• a complex polysaccharide derived from a marine alga (agarophytes)
  
  • a polymer of galactose and galacturonic acid
  • isolated from seaweed agarocytes in the seaweed
• a solidifying agent added to the medium to create a solid medium
• it is NOT a nutrient itself

Question 6

agar concentrations

Answer 6

• normal agar: 1.5% (weight per volume)
  
  • eg - 15g per liter of water
• soft agar: 0.5% (weight per volume)
  
  • often used for overlays

Question 7

why can most bacteria not digest agar?

Answer 7

• most bacteria lack agarase, an enzyme that can digest agar

Question 8

chemically-defined medium

Answer 8

• a medium whose exact chemical composition is known
• also known as a synthetic medium

Question 9

fastidious organisms

Answer 9

organisms that require many growth factors

Question 10

complex medium

Answer 10

• a medium whose exact chemical composition is basically unknown
• often made up of yeast, meat, protein, and plant extracts at various amounts

Question 11

semi-defined medium

Answer 11

• a medium whose chemical composition is partially known
• between chemically-defined medium and complex medium

Question 12

liquid medium

Answer 12

a complex medium in liquid form

Question 13

reducing medium

Answer 13

• medium that contains ingredients that chemically combine with dissolved oxygen and deplete the oxygen in the culture medium
• used to grow obligate anaerobes

Question 14

uses of bacterial media

Answer 14

1. enrichment
2. selective
3. differential
4. (selective and differential)
5. maintenance

Question 15

bacterial media for enrichment

Answer 15

• allows organisms to grow on the basis of what they prefer
• designed to increase numbers of desired microbes to detectable levels
• Winogradsky column

Question 16

bacterial media for selection

Answer 16

• adds an inhibitory agent that will prevent some bacteria from growing while allowing others to grow
• suppresses unwanted microbes and encourages desired microbes
• eg - antibiotics, basic dyes, bismuth sulfite agar

Question 17

bacterial media for differentiating

Answer 17

• addition of something that will differentiate (not inhibit) between microbes
• eg - milk agar, pH indicator, blood agar

Question 18

bacterial media for maintaining

Answer 18

• used to maintain and preserve microorganisms for long-term

Question 19

bacterial media for selecting and differentiating

Answer 19

• supresses unwanted microbes and differentiates colonies of desired microbes from each other
• eg - MSA (mannitol salt agar), EMB (eosin-methylene blue agar)

Question 20

bacterial nutrition patterns

Answer 20

1. energy source
2. carbon source
3. electron donor source (reducing power)

Question 21

chemotrophs

Answer 21

• obtain energy from chemicals

Question 22

phototrophs

Answer 22

• energy source is electromagnetic radiation - sunlight

Question 23

heterotrophs

Answer 23

• organic carbon source
  
  • C w/H = organic

Question 24

autotrophs

Answer 24

• inorganic carbon source
  
  • C w/o H = inorganic
    
    • eg - carbon dioxide

Question 25

organotroph

Answer 25

* an organic compound is the electron donor source

Question 26

lithotroph

Answer 26

* inorganic electron donor source

Question 27

which nutritional classification are humans?

Answer 27

chemoheteroorganotrophs

Question 28

which nutrition classifications are bacteria?

Answer 28

bacteria can be combinations of any of these three sources, resulting in high diversity

Question 29

who invented the petri dish?

Answer 29

Julius Richard Petri

Question 30

who developed bacteriological media?

Answer 30

Robert Koch

Question 31

who discovered agar?

Answer 31

* Walther and Fannie Heese * Both worked in Koch's lab * Koch took credit for their discovery

Question 32

what was the first type of bacteria cultured with agar?

Answer 32

* *Mycobacterium tuberculosis* * It was the first time that it had ever been cultured * Cultured by Koch

Question 33

What was the principal reason for developing methods to culture and isolate microorganisms?

Answer 33

The principal reason was to identify bacterial agents of disease

Question 34

*Vibrio cholerae*

Answer 34

* Causes cholera

Question 35

*Bacillus anthracis*

Answer 35

* Causes anthrax

Question 36

*Mycobacterium tuberculosis*

Answer 36

* Causes tuberculosis

Question 37

*Corynebacterium diphtheriae*

Answer 37

* Causes diphtheria

Question 38

Biogeochemical cycles

Answer 38

* The ways in which an element or compound moves between various living and nonliving forms and locations in the biosphere * There are six elements that are principally involved in these cycles.

Question 39

Essential elements of life

Answer 39

* CHNOPS * carbon * hydrogen * nitrogen * oxygen * phosphorus * sulfur * Involved in the biogeochemical cycles * Most exist in both organic and inorganic forms

Question 40

Examples of inorganic and organic nitrogen sources

Answer 40

* Inorganic * ammonia * Organic * amino acids

Question 41

Examples of inorganic and organic sulfur sources

Answer 41

* Inorganic * hydrogen sulfate, sulfite, sulfate * Organic * sulfur-containing amino acids * enable junction between N and S cycles

Question 42

Examples of inorganic and organic sources of phosphorus

Answer 42

* Inorganic * phosphate * Organic * biomolecules

Question 43

What are the major trace elements? What are their functions?

Answer 43

* Magnesium (Mg) * stabilizes the negative charge of the cell membrane/cell wall * Calcium (Ca) * balances ionic strength * maintains the equilibrium of potassium between external and internal * Iron (Fe) * found within the proton chain

Question 44

What are the minor trace elements? What are their functions?

Answer 44

* Boron (B) * Nickel (Ni) * Zinc (Zn) * Molybdenum (Mo) * Serve as cofactors for specific enzymes * eg - nitrogenase and nitrate reductase require Mo to be synthesized and to function

Question 45

The 3 cardinal temperatures of growth

Answer 45

1. minimal temperature - the lowest temperature that is required for growth 2. optimum temperature - the ideal temperature * skewed towards the maximum 3. maximum temperature - the highest temperature that allows growth

Question 46

Psychrophiles

Answer 46

* Range = -5 to 20 C * Optimum = 5-10 C

Question 47

Psychrotrophs

Answer 47

* Optimum = 15 to 20 C * Can grow at temperatures below 0 C (like psychrophiles), but have a higher optimal temperature * Therefore also known as facultative psychrophiles

Question 48

Mesophiles

Answer 48

* Range = 15-45 C * Optimum = 30-37 C * The majority of organisms * High diversity

Question 49

Thermophiles

Answer 49

* Higher temperature range of 45-80 C

Question 50

Extremophiles

Answer 50

* Highest temperature range * Optimal = \>80 C