Micro Exam 3 - Redox Reactions, Respiration, Lithotrophy

What is a redox reaction?

the movement of electrons from a donor to an acceptor

What does hydrogen loss indicate?

oxidation

What does hydrogen gain indicate?

reduction

How do you use the electron tower?

1 - find the two half reactions, 2 - reverse sign on energy value of higher half reaction, 3 - add to energy value of lower half reaction

More steps =

more opportunity for proton export

How is a lot of energy released in electron transport chain?

by passing electrons from NADH to O2

What does the amount of ATP that can be made depend on?

electron transport chain used

What is efficiency?

a description of how much energy an organism can convert from a source

What is "eating"?

taking electrons off of a molecule

What is "breathing"?

putting electrons on to a molecule

What is aerobic respiration?

electrons pass through ETC to oxygen and creates PMF

What is anaerobic respiration?

electrons pass through ETC to a molecule other than oxygen and creates PMF

What is lithotrophy?

oxidation of inorganic electron donors to supply ETC

What is lithotrophy often coupled to and why?

O2 because weak energy sources require a strong oxidant for maximum energy conversion

What have some bacteria evolved to be able to do?

eat electron rich, inorganic molecules

What inorganic, electron rich molecules have some bacteria evolved to be able to eat?

hydrogen gas (H2), nitrite (NO2-), ammonia (NH3), elemental sulfur (S0), sulfide (H2S), and iron (Fe2+)

What is hydrogen oxidation?

direct donation using hydrogenase to reduce NADH (electron rich - lots of energy)

How is PMF made in sulfide oxidation?

ETC

How is ATP made in sulfide oxidation?

F1F0ATPase

How is NADH made in sulfide oxidation?

reverse ETC

Iron oxidation is...

one of the most efficient processes imaginable

What is bad about iron oxidation?

lots and lots of iron atoms must be stripped of electrons to make PMF, 1 ATP, and 1 NADH which is very slow

What is good about iron oxidation?

little competition for the source, extremely abundant so amount of atoms needed doesn't matter

If cells can make PMF...

they can make ATP and NADH