NAD+ and FAD Redox Reactions

Question 1

NAD+

Answer 1

A co-enzyme used in several redox reactions.

Question 2

Redox Reaction

Answer 2

Reactions where both reduction and oxidation reactions take place.

Question 3

Oxidation

Answer 3

Loss of electrons or increase in oxidative state.

Question 4

Reduction

Answer 4

An increase in number of electrons.

Question 5

Hydride Ion

Answer 5

H-, a proton with two electrons.

Question 6

What is the structure of NAD+?

Answer 6

A hexagonal ring with a hydrogen on CA a NH2-C=O on C2 and a nitrogen at C4 bound by an R group.

Question 7

What part of NAD+ structure is nicotinamide?

Answer 7

The hexagonal ring.

Question 8

What molecule is the R group?

Answer 8

Ribose phosphophoryl-adenosine portion

Question 9

What structural changes occur when NAD+ is reduced to NADH?

Answer 9

Addition of a hydride to C1, along with the other hydrogen.

Question 10

What is the terminal electron acceptor in aerobic organisms?

Answer 10

O2

Question 11

Why type of electron does O2 accept only?

Answer 11

Unpaired electrons.

Question 12

Unpaired Electrons

Answer 12

Electrons that must be transferred to O2 one at a time.

Question 13

Why do oxygens two lone electrons not pair up?

Answer 13

As they are in seperate orbitals.

Question 14

A Radical

Answer 14

A molecule containing at least one unpaired electron.

Question 15

What can FAD accept to produce stable FADH/FADH2?

Answer 15

Either one OR two electrons.

Question 16

What is the structure of the Flavin portion of FADH?

Answer 16

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

Question 17

Where are the double bonds in FADH flavin portion?

Answer 17

C1-C2, C3-C4 and C5-C6 in R1, whilst R2 has none, and R3 has double bonds between C1-C6

Question 18

How does FAD differ from FADH?

Answer 18

There is no hydrogen at R2, N4, instead a double bond between C3-N4.

Question 19

How does FADH2 differ from FAD?

Answer 19

There is an additional hydrogen at R3 N1, with a double bond between R2 C2-C3.

Question 20

In terminology, how does FADH and FADH2 relate to FAD?

Answer 20

FADH is the radical form whilst FADH2 the reduced.

Question 21

Why do NAD+ and FAD require reversible reduction?

Answer 21

So that they can accept electrons and pass them to an electron carrier to be regenerated.

Question 22

Why is the ability for NAD+ and FAD passage onto electron carriers important?

Answer 22

Allows them to participate in additional cycle of redox reactions.

Question 23

The Nernest Equation

Answer 23

This defines the relationship between redox potential and standard potential and to the activities of the electroactive species.

Question 24

Redox Potential

Answer 24

A measure of chemical species tendency to acquire electrons from, or lose electrons to an electrode, to be reduced/oxidised.

Question 25

Standard Potential

Answer 25

A measure of reducing power of an element/compound.

Question 26

What is an example of a Oxidation-Reduction reaction?

Answer 26

Fe3+ + Cu+ <---> Fe2+ + Cu2+

Question 27

Who is the reductant and who is the oxidant in Fe3+ + Cu+ <---> Fe2+ + Cu2+?

Answer 27

Copper the reductant, oxidised to Cu2+. whilst Fe3 the oxidant, reduced to Fe2.

Question 28

What is Fe3+ + Cu+ <---> Fe2+ + Cu2+ in half reactions?

Answer 28

Fe3+ + e- <---> Fe2+ and Cu+ <---> Cu2+ + e-

Question 29

Where does copper and iron redox occur?

Answer 29

Oxidation of cytochrome C oxidase in the MC.

Question 30

What components do half-reactions have?

Answer 30

An electron donor and electron acceptor

Question 31

Electrochemical Cell

Answer 31

A device that can generate electrical energy from the chemical reactions within it, or use electrical energy to facilitae chemical reactions.

Question 32

What is an example of an Electrochemical Cell?

Answer 32

Batteries

Question 33

How do redox reactions relate to an electrochemical cell?

Answer 33

Each half reaction takes place in a seperate half-cell.

Question 34

How are half-cells connected?

Answer 34

Electrical currents in a wire connecting two electrodes.

Question 35

What is the process of an electrochemical cell, biochemically?

Answer 35

Salt bridges complete an electrical circuit providing a conduit for ion migration and electric neutrality maintenance.

Question 36

The Faraday Constant

Answer 36

Electrical charge carried by one mole, or avogadros number, of electrons.

Question 37

Volts

Answer 37

Number of joules required to transfer 1 coulomb of charge.