chapter 3+14

how is energy conserved ie how is ATP produced (there are 3 mechanisms)

1. substrate-level phosphorylation → ATP synthesis is directly coupled to an energy generating reaction

2. electron transport phosphorylation ie oxidative-phosphorylation. electrons are used to generate a protomotive force, through a series of electron carrier protein complexes this is coupled to ATP synthase , thereby it INDIRECTLY generates ATP

3. photophosphorylation ie, light energy is used to make ATP

how is energy conserved in chemorganotrophs?

through 2 mechanisms

1. fermentation (anaerobic catabolism in which organic compounds donate and accept electrons)

2. respiration(aerobic or anaerobic catabolism. Aerobic→ o2 is the final acceptor anaeroic if another compound is the final acceptor)

what is glycolysis used for?

1. fermentation

2. aerobic respiration

3. anaerobic respiration

glycolyis stages

1. preparatory stage → no redox reactions, there is investment of ATP

2. redox stage - formation of atp, pyruvate and nadh

3. fermentation stage- intermediates act as electron acceptors,NADH → nad+

principles of fermentation

• anaerobic

• only uses substrate-level phosphorylation

• less ATP is produced

• oxidized intermediates are used as e- acceptors.

examples of energy rich compounds which can couple to substrate level phosphorylation

acetyl-coA, 1,3-bisphosphoglycerate and phosphoenolpyruvate

Advantages of fermentation

energy rich intermediates trigger substrate-level phosphorylation

besides the reduction of pyruvate redox balance can be obtained through h2

disadvantages of fermentation

• shortage on external e- acceptors so difficult to reach redox balance

• dependent on substrate level phosphorylation→ so less energy available

what is pmf used for?

1. ATP production

2. movement

3. active transpor