Lecture 3- Classes of microorganisms

Question 1

metabolism

Answer 1

the sum total of all of the chemical reactions that occur in a cell

Question 2

difference between catabolic reactions and anabolic reactions?

Answer 2

catabolism: energy releasing (break something down)
anabolism: energy requiring (build something up)

Question 3

microorganisms can be categorized into classes according to what 3 sources?

Answer 3

energy source
electron source
carbon source

Question 4

what are chemorganotrophs?

Answer 4

energy source: chemical
electron source: organic chemicals
carbon source: CO2
autotrophs

Question 5

what are chemolithoheterotrophs?

Answer 5

energy source: chemical
electron source: inorganic chemicals
carbon source: organic carbon
heterotrophs

Question 6

what are phototrophs?

Answer 6

energy source: light
electron source: phototrophy (H2O)

Question 7

what are the basic elements we need to survive?

Answer 7

C HOPKNS CaFe Mg

Question 8

what is in a basic medium? energy source? electron source? carbon source? nitrogen source?

Answer 8

energy source: light
electron source: H2O
carbon source: CO2
nitrogen source: N2

Question 9

can any microbes grow on a basic medium?

Answer 9

nitrogen fixing photolithoautotroph can grow
nitrogen and carbon fixation bacteria can grow
ex. cyanobacteria

Question 10

why would we add other components to a basic medium?

Answer 10

to allow growth of other organisms

Question 11

if we add NH4Cl to a basic medium what can grow? what does NH4Cl give the medium?

Answer 11

gives medium N source
allows non nitrogen fixing photolithoautotrophs to grow some chemolithoautotrophs can grow

Question 12

if we add NH4Cl and glucose to a basic medium what can grow? what does the addition of glucose give us?

Answer 12

addition of glucose gives reduced organic carbon source some chemoorganotrophs can grow (ex. E. coli, bacillus)

Question 13

if we add NH4Cl, glucose and nicotinic acid to a basic medium what can grow? what does the addition of nicotinic acid give us?

Answer 13

nicotinic acid gives us vitamins
chemoorganoheterotrophs with a growth factor requirement can grow

Question 14

if we add Glucose and yeast extract to a basic medium what can grow? what does the addition of yeast extract give us?

Answer 14

yeast extract gives us a source of amino acids (N source), purines, pyrimidines and vitamins
very picky organisms can grow (organisms with a lot of requirements)

Question 15

what are the 3 classes of culture media?

Answer 15

defined medium
minimal medium
complex medium

Question 16

what is a defined medium?

Answer 16

exact chemical composition is known (useful to study metabolism)

Question 17

what is a minimal medium?

Answer 17

a defined medium that provides the minimum nutritional requirements for growth

Question 18

what is a complex medium? what is it made of? what do they supply?

Answer 18

exact chemical composition is not known (undefined)
often made from meat or yeast extracts
supply a wide range of growth factors

Question 19

what does a differential medium do?

Answer 19

allows different bacteria to be distinguished (each organism on the plate will show up differently)

Question 20

what is an example of a differential medium? explain how it works

Answer 20

blood agar (made of T-soy plate + 5% sheeps blood)
allows for differentiation of hemolytic bacteria

Question 21

what is a selective medium?

Answer 21

contains ingredients that inhibit the growth of unwanted microbes (allow only specific microbes to grow)

Question 22

what is an example of a selective medium? explain it

Answer 22

mannitol salt agar
contains very high salt so that not many organisms can grow

Question 23

what is an enriched medium?

Answer 23

supplemented with special nutrients to encourage the growth of fastidious bacteria and has complex nutrient requirements (require many growth factors)