6 - Biological Oxidation and Reduction Flashcards Preview

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Flashcards in 6 - Biological Oxidation and Reduction Deck (9)
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1

If ΔE* (reduction potential) is more positive than ΔG* is

Negative, and vice versa. A reduction potential is positive in spontaneous reactions. Electrons flow from a species with a more negative E* to a species with a more positive E*

2

Living organisms use redox coenzymes for what

As high energy electron carriers (eg. NADH and FADH2)

3

What is the biochemical reference half reaction? What is the reduction potential of this reversible half reaction?

2H + 2e- -> H2 -0.42 V

4

What is the conventional direction for half reactions to be writtern in?

Each is written as a reduction.

5

What does reduction potential magnitude mean?

High reduction potential (eg. above 0) means greater tendency to become reduced and low reduction potential means they are better at donating electrons

6

Do enzymes have an effect on reaction spontaneity?

Enzymes do not affect if a reaction is spontaneous or not, they only speed it up. Only the redox potential and resulting ΔG determine the direction that is favoured and that will be spontaneous.

7

What direction do electrons flow in redox reactions

Electrons flow spontaneously from a species with a more negative E*' to a species with a more positive E*'.

8

How can redox potential (ΔE) be measured?

By setting up two half reactions in seperate containers connected by a salt bridge, and voltmeter (electrochemical cell). Voltmeter is set up between the wires connecting to anode and cathode (usually made out of platinum).

ΔE° = E°(electron acceptor) - E°(electron donor)

9

Reactions with large negative reduction potentials have oxidized forms with the smallest tendency to accept electrons and become reduced. Therefore reduction potential E° is a measure of?

Reduction potential is measure of A REACTION (not a species). The reducing agent is always written to the right of the oxidizing agent and the number of electrons transferred.