Fermentation

Question 1

what do organisms that only use fermentation lack?

Answer 1

• ETC!
• these are some chemoorganoheterogrophs
• when no O2 is available, some organisms (some chemoorganoheterotrophs and facultative anaerobes) repress expression/synthesis of ETC

Question 2

difference between fermentation and anaerobic respiration

Answer 2

• fermentation: use organic e- acceptor instead of O2
• anaerobic respiration: use inorganic e- acceptor instead of O2
• both don’t use O2!!

Question 3

what are the electron donors and acceptors in fermentation?

Answer 3

• donor: glucose
• acceptor: pyruvate or a pyruvate derivative

Question 4

why is fermentation typically the last resort for organisms who prefer oxygen?

Answer 4

aerobic respiration yields much more ATP (38) than fermentation (2)

Question 5

pathways used during fermentation?

Answer 5

• glycolysis only, no TCA or ETC
• this is substrate-level phosphorylation
• fermentation pathways oxidize NADH to NAD+ and reduce an organic e- acceptor (pyruvate or derivative)
• if this were anaerobic respiration, the e- donor would be inorganic!!!

Question 6

what are the organisms that can do fermentation?

Answer 6

chemoorganoheterotrophs

Question 7

how can we use fermentation to identify/classify bacteria?

Answer 7

• by looking at the different fermentation products that they make!
• however, all of they will use pyruvate or a pyruvate derivative (organic) as the final e- acceptor to oxidize NADH to NAD in glycolysis

Question 8

chemolithoautotrophy

Answer 8

• oxidation of inorganic molecules
• these microbes donate e- to their ETC’s by oxidizing inorganic chemicals
• ETC is the only process happening here!
• very few species are chemolithoautotrophs
• each species has a specific set of inorganic e- donors and inorganic e- acceptors

Question 9

is chemolithoautotrophy aerobic or anaerobic?

Answer 9

• both!
• ETC can either reduce O2 or something like nitrate

Question 10

relate standard reduction potential to energy gain/loss

Answer 10

• energy is gained when e- are passed from donors (more - Eo) to acceptors (more + Eo)

Question 11

what do chemolithoautotrophs make?

Answer 11

they make a lot of inorganic matter to break down to make enough energy to fix CO2 into biological molecules that they need

Question 12

what do photolithoautotrophs do?

Answer 12

• capture sunlight energy, convert it to ATP and NADPH
• then use the ATP and NADPH to fix CO2 into organic molecules
• this produces CO2
• provides organic molecules used by heterotrophs

Question 13

2 rxns of photosynthesis

Answer 13

• light rxns: light energy is trapped and converted into chemical energy (ATP)
• dark rxns: ATP is used to fix CO2 into organic molecules