18: metabolism

Question 1

Is it possible for some bacteria to do aerobic resp and not have cytochrome C oxidase?

Answer 1

yes; E. coli does aerobic resp and is negative on the test

Question 2

How does the oxidase test work? Can you shake the tube to further mix it?

Answer 2

the oxidase reagent is oxidized by cytochrome C oxidase, turning it pink shortly after; No, shaking the tube aerates the reagents giving a false positive test.

Question 3

Is E. coli negative or positive in the oxidase test? what about the Vibrios?

Answer 3

negative, but can undergo aerobic resp; positive

Question 4

Where does the energy come from to make the proton gradient? What does this cause?

Answer 4

energy from the oxidation of NADH + H+ and FADH2 pushes protons across the cyto membrane, creating a high [H+] in the peri and low [H+] in the cytoplasm

Question 5

Where does the energy to make ATP come from?

Answer 5

when the protons diffuse thru ATP synthase

Question 6

what is oxidized in oxidative phosphorylation? phosphorylated?

Answer 6

NADH + H+ and FADH2; ADP

Question 7

What is ATP synthase? what is it powered by?

Answer 7

a multi subunit protein powered by the proton motive force

Question 8

what are the 3 main components of ATP synthase?

Answer 8

proton channel, rotor, catalytic knob

Question 9

what part of ATP synthase converts ADP to ATP? ATP is broken down to ATP in what kind of rxn that involves water? this rxn is considered what?

Answer 9

catalytic knob; hydrolytic; exergonic

Question 10

How does ATP synthase work? (where do the protons come from and where do they go and what do they do?)

Answer 10

protons from periplasm diffuse thru the proton channel, this causes the rotor to turn, which powers the catalytic knob, so ATP + Pi can be converted to ATP

Question 11

when oxidation reduction rxns take place, there are ____________________ or _____________ produced, they can cause a lot of damage to biological molecules.

Answer 11

reactive oxygen species or free radicals

Question 12

what is an enzyme that is produced by bacteria to cope w ROS that gets rid of hydrogen peroxide, converting it to oxygen and water?

Answer 12

catalase

Question 13

In one of the ROS tests, you add hydrogen peroxide to bacteria, if the org makes catalase how would the org respond?

Answer 13

the plate/ slant would start bubbling

Question 14

when macrophages engulf a bacterium, they go through a ____________________, where they take up oxygen and convert it to ________________________________

Answer 14

respiratory burst; toxic oxygen products (ROS)

Question 15

what are the 3 toxic oxygen species (ROS) produced by the bacterium? why are these substances produced?

Answer 15

superoxide, hydrogen peroxide, hypochloric acid; to kill the bacterium

Question 16

which ROS mentioned is a component of bleach?

Answer 16

hypochloric acid

Question 17

when does anaerobic resp occur? under what condition (what’s an example of this) ?

Answer 17

oxidative phosphorylation; occurs if another inorganic compound besides oxygen is the fea; nitrate

Question 18

what pathway produces the most ATP? the second most? the least?

Answer 18

aerobic resp, anaerobic resp, fermentation

Question 19

what does the nitrate reductase test determine?

Answer 19

if an organism undergoes anaerobic resp in which nitrate reductase is involved

Question 20

What is a positive rxn in the nitrate reductase test? what is unusual about this test?

Answer 20

the tube will turn pink; we are able to confirm a negative rxn by adding zinc to the tube.

Question 21

when nitrate reductase is used at the end of the electron transport chain, nitrate is reduced to what?

Answer 21

nitrite and water?

Question 22

An organism that is nitrate reduction + would take place in

Answer 22

anaerobic resp

Question 23

what does the thioglycolate test determine?

Answer 23

how well the organism deals w oxygen

Question 24

how does the thioglycolate test work?

Answer 24

bacteria are placed in a heated tube containing agar, they are dispersed through out the tube, the media solidifies. the bacteria grows where they are most suited to grow.

Question 25

thioglycolate is a reducing agent, what does it reduce?

Answer 25

oxygen to water

Question 26

an obligate aerobe does what kind of metabolism? does it require oxygen? what is an example of this?

Answer 26

aerobic resp; yes; Micrococcus luteus (slow growing yellow bacteria)

Question 27

an obligate anaerobe does what kind of metabolism? does it require oxygen? what’s an example of this?

Answer 27

anaerobic resp or fermentation; no can’t tolerate oxygen; Clostridium species

Question 28

what organism causes botulism, and can grow in canned green beans where almost no oxygen is present?

Answer 28

Clostridium botulinum

Question 29

what kind of metabolism is done by an aerotolerant anaerobe? does it require oxygen? what is an example?

Answer 29

fermentation; no, but it can tolerate it; Streptococcus pyogenes

Question 30

what does Streptococcus pyogenes cause?

Answer 30

strep throat

Question 31

what kind of metabolism does a facultative aerobe have? does it need oxygen? what is an example?

Answer 31

aerobic and anaerobic resp and fermentation; no, but do better if oxygen is present; E. coli

Question 32

what kind of metabolism does a microaerophile have? does it need oxygen? what is an example?

Answer 32

aerobic resp; yes, but cannot tolerate high levels of it; Helicobacter pylori

Question 33

what kind of organism is the most metabolically versatile?

Answer 33

facultative aerobe