NAD+ and FAD Redox Reactions Flashcards
NAD+
A co-enzyme used in several redox reactions.
Redox Reaction
Reactions where both reduction and oxidation reactions take place.
Oxidation
Loss of electrons or increase in oxidative state.
Reduction
An increase in number of electrons.
Hydride Ion
H-, a proton with two electrons.
What is the structure of NAD+?
A hexagonal ring with a hydrogen on CA a NH2-C=O on C2 and a nitrogen at C4 bound by an R group.
What part of NAD+ structure is nicotinamide?
The hexagonal ring.
What molecule is the R group?
Ribose phosphophoryl-adenosine portion
What structural changes occur when NAD+ is reduced to NADH?
Addition of a hydride to C1, along with the other hydrogen.
What is the terminal electron acceptor in aerobic organisms?
O2
Why type of electron does O2 accept only?
Unpaired electrons.
Unpaired Electrons
Electrons that must be transferred to O2 one at a time.
Why do oxygens two lone electrons not pair up?
As they are in seperate orbitals.
A Radical
A molecule containing at least one unpaired electron.
What can FAD accept to produce stable FADH/FADH2?
Either one OR two electrons.
What is the structure of the Flavin portion of FADH?
Three cyclical rings, R1 containing methyl at C5 and C6, R2 containing N replacing C1 and C4, whilst R3 contains a N replacing C1 and C4, and carboxyl at C2 and C4
Where are the double bonds in FADH flavin portion?
C1-C2, C3-C4 and C5-C6 in R1, whilst R2 has none, and R3 has double bonds between C1-C6
How does FAD differ from FADH?
There is no hydrogen at R2, N4, instead a double bond between C3-N4.
How does FADH2 differ from FAD?
There is an additional hydrogen at R3 N1, with a double bond between R2 C2-C3.
In terminology, how does FADH and FADH2 relate to FAD?
FADH is the radical form whilst FADH2 the reduced.
Why do NAD+ and FAD require reversible reduction?
So that they can accept electrons and pass them to an electron carrier to be regenerated.
Why is the ability for NAD+ and FAD passage onto electron carriers important?
Allows them to participate in additional cycle of redox reactions.
The Nernest Equation
This defines the relationship between redox potential and standard potential and to the activities of the electroactive species.
Redox Potential
A measure of chemical species tendency to acquire electrons from, or lose electrons to an electrode, to be reduced/oxidised.
Standard Potential
A measure of reducing power of an element/compound.
What is an example of a Oxidation-Reduction reaction?
Fe3+ + Cu+ <—> Fe2+ + Cu2+
Who is the reductant and who is the oxidant in Fe3+ + Cu+ <—> Fe2+ + Cu2+?
Copper the reductant, oxidised to Cu2+. whilst Fe3 the oxidant, reduced to Fe2.
What is Fe3+ + Cu+ <—> Fe2+ + Cu2+ in half reactions?
Fe3+ + e- <—> Fe2+ and Cu+ <—> Cu2+ + e-
Where does copper and iron redox occur?
Oxidation of cytochrome C oxidase in the MC.
What components do half-reactions have?
An electron donor and electron acceptor
Electrochemical Cell
A device that can generate electrical energy from the chemical reactions within it, or use electrical energy to facilitae chemical reactions.
What is an example of an Electrochemical Cell?
Batteries
How do redox reactions relate to an electrochemical cell?
Each half reaction takes place in a seperate half-cell.
How are half-cells connected?
Electrical currents in a wire connecting two electrodes.
What is the process of an electrochemical cell, biochemically?
Salt bridges complete an electrical circuit providing a conduit for ion migration and electric neutrality maintenance.
The Faraday Constant
Electrical charge carried by one mole, or avogadros number, of electrons.
Volts
Number of joules required to transfer 1 coulomb of charge.
