6 - Biological Oxidation and Reduction Flashcards

1
Q

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

A

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*

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2
Q

Living organisms use redox coenzymes for what

A

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

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3
Q

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

A

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

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4
Q

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

A

Each is written as a reduction.

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5
Q

What does reduction potential magnitude mean?

A

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

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6
Q

Do enzymes have an effect on reaction spontaneity?

A

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.

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7
Q

What direction do electrons flow in redox reactions

A

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

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8
Q

How can redox potential (ΔE) be measured?

A

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)

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9
Q

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?

A

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.

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