Terms

Question 1

Buffers

Answer 1

Chemicals incorporated into growth media to maintain a favorable pH range of the medium during growth

Question 2

Extracts

Answer 2

Eukaryotic tissues, extracted by boiling and drying to paste/powder, used as a source of amino acids, vitamins, and coenzymes (many are needed growth factors for fastidious organisms)

Question 3

Peptones

Answer 3

Complex mixtures of organic and inorganic compounds, from digestion of animal and plant tissues, contain peptides and single amino acids

Question 4

pH indicator

Answer 4

acid-base indicator, added to media to detect pH changes

Question 5

Reducing agents

Answer 5

Stimulate growth by reducing the oxidation-reduction potential in the environment, good for growing anaerobes

Question 6

Selective agents

Answer 6

antimicrobial agents, antibiotics, can be put in media to suppress or inhibit the growth of certain groups of microorganisms while allowing the growth of others, usually bacteriostatic

Question 7

Bacteriostatic

Answer 7

inhibits growth, does not kill the bacteria

Question 8

Saline

Answer 8

NaCl solution, compatible with almost all species we will look at, an excellent diluent (dilutant)

Question 9

All-purpose medium

Answer 9

rich in a wide variety of nutrients, will support the growth of a wide range of bacteria

Question 10

Enrichment media

Answer 10

favors the growth of certain microbes over other types

Question 11

Selective media

Answer 11

supports the growth of desired organisms while not allowing the growth of many other unwanted organisms

example: nitrogen-free broth

Question 12

Differential media

Answer 12

one that lows two or more different physiological types or organisms to grow, but contains components that allow for visual differentiation of the different types (e.g. by using pH sensitive dyes)

Question 13

Strict aerobes (obligate aerobes)

Answer 13

only use respiratory-type metabolism, use oxygen as the terminal electron acceptor, require oxygen for growth, can grow in normal air atmosphere

Question 14

Strict respirers

Answer 14

only have a respiratory-type metabolism, use oxygen OR other electron acceptors as the terminal electron acceptor, can grow anaerobically by anaerobic respiration and use something other than oxygen as the terminal electron acceptor, they are not dependent on the presence of oxygen

Question 15

Microaerophiles

Answer 15

require oxygen in their metabolism, usually for respiration, but cannot grow under normal atmospheric oxygen conditions, they have optimal growth at much lower oxygen concentrations

Question 16

Facultative anaerobes

Answer 16

can grow by aerobic respiration and also by anaerobic respiration, can also get energy from fermentation, they grow more in the presence of oxygen but do not require it

Question 17

Aerotolerant anaerobes

Answer 17

separate group from facultative anaerobes, cannot respire, indifferent to oxygen presence, obtain energy ONLY from fermentation and have the same growth rate in both anaerobic and aerobic conditions

Question 18

Strict anaerobes (obligate anaerobes)

Answer 18

oxygen is toxic to them, no growth under aerobic conditions, may use fermentation, anaerobic respiration, or both for their metabolism

Question 19

Defined medium

Answer 19

the exact chemical composition of the culture medium is known

Question 20

Complex medium

Answer 20

the exact chemical composition of the medium is not known, often prepared from complex materials (e.g. tissue extracts, infusions)

Question 21

Rich medium

Answer 21

a medium that contains an abundance of nutrients of all types

Question 22

Agar

Answer 22

impure polysaccharide gum, from marine algae, most common solidifying agent for solid media, resistant to degradation by most organisms, relatively clear

dissolves at 100ºC, stays liquid until 45ºC, but will not melt until brought back up to 100ºC

Question 23

Growth factor

Answer 23

a specific organic compound that is required by a particular organism, as it cannot be synthesized by that organism

Question 24

Fastidious

Answer 24

organisms that require a variety of growth factors

Question 25

Light microscope

Answer 25

has an optical system for magnification and an illumination system to make the specimen visible, cannot see sub-cellular structures with this

Question 26

Enrich

Answer 26

create growth conditions that favor the growth of a particular microbe or a group of microbes

Question 27

Select

Answer 27

create growth conditions that prevent or eliminate most groups of microbes os that only the desired microbe or group of microbes grows

Question 28

Binary fission

Answer 28

A type of bacterial growth that involves the mother cell dividing into two daughter cells of approximately equal size

Question 29

Budding

Answer 29

A type of bacterial growth that involves an asymmetric creation of a growing bud that eventually severs from the parental cell

Question 30

Filamentous growth

Answer 30

A type of bacterial growth characterized by the formation of long, branching, non-divided filaments, containing multiple chromosomes, which sometimes have cross-walls

Question 31

Plate count assay

Answer 31

A straightforward way to quantify the number of live cells in a sample that also obtains pure cultures of the organism - spread a sample on a Petri plate and count the number of colonies that grow, which is proportional to the number of cells in the original culture

Question 32

Serial dilution

Answer 32

a way of making large dilutions accurately using small volumes, each dilution factor is multiplied to get the final dilution

Question 33

Colony forming units

Answer 33

CFUs, used instead of cells as more than one cell can produce one colony, and not all microbes may grow in laboratory conditions.

Question 34

Lag phase

Answer 34

the phase of bacterial growth when an organism is inoculated into a new medium and it needs to acclimate to the new nutrients, synthesize RNA, protein and then replicates DNA, all before division starts. No increase in cell numbers.

Question 35

Log phase

Answer 35

A period of maximal division, can last for hours or days, exponential/growth phase

Question 36

Stationary phase

Answer 36

Increase in cell number ceases, usually due to a limiting nutrient or an accumulation of a toxic waste product

Question 37

Death phase

Answer 37

Final chapter of a growth curve, there is an exponential decrease in the number of organisms due to cell death

Question 38

Chemotrophs

Answer 38

generate energy by the oxidation of chemical compounds (organic or inorganic)

Question 39

Phototrophs

Answer 39

Get energy solely from an electron transport system powered by light

Question 40

Organotrophs

Answer 40

organisms that get their reducing power (electrons) from organic compounds such as sugars, fats, proteins

Question 41

Lithotrophs

Answer 41

Organisms that get their reducing power from inorganic chemicals

Question 42

Heterotrophs

Answer 42

utilize organic sources for cellular carbon

Question 43

Autotrophs

Answer 43

Get cellular carbon from CO2

Question 44

Chemoheterotrophs

Answer 44

organisms that derive their energy from chemicals and utilize organic carbon

Question 45

Chemoautotrophs

Answer 45

Use CO2 as the source of cell carbon

Question 46

Phototrophs

Answer 46

get energy from light and usually are photoautotrophic

Question 47

Mixotrophs

Answer 47

“grab bag” class, contains organisms that perform some combination of metabolic pathways