ETC

Question 1

Which enzyme from the TCA cycle is involved in the ETC?

Answer 1

Succinyl dehydrogenase

Question 2

What are the roles of ATP?

Answer 2

-serves as a mediator of biological energy transfer
-Links the energy yielding, exergonic processes and the energy- requiring endergonic processes so that they occur spontaneously.
-represents stored form of energy in the cells

Question 3

What is enthalpy and change in enthalpy?

Answer 3

Heat content of physical object or system
Change in enthalpy (∆H)-heat absorbed or released during a reaction

Question 4

What is entropy and change in entropy?

Answer 4

Randomness or disorder of a system.
Change in entropy (∆S) degree of randomness created during reaction

Question 5

What is free energy and change in free energy?

Answer 5

Energy available for doing work in a system
∆G-change in free energy occurring during biological reactions.
∆G=∆H-T∆S

Question 6

Are exergonic reactions negative or positive?

Answer 6

Negative

Question 7

Are endergonic reactions negative or positive?

Answer 7

Positive

Question 8

A chemical reaction can occur spontaneously if they are accompanied by a____ in free energy (∆G)

Answer 8

Decrease

Question 9

When ∆G becomes ____ (∆G=0) the reaction is at ____

Answer 9

Zero and equilibrium

Question 10

The reaction is said to be exergonic if there is a ____ of Free energy (∆G)

Answer 10

loss

Question 11

The reaction is said to be endergonic if the energy has to be ______ to the reactants

Answer 11

Supplied

Question 12

Which reaction occurs spontaneously and which reaction doesn’t?

Answer 12

Spontaneously: Exergonic
Non-spontaneous: Endergonic

Question 13

If the ∆G of the forward reaction (A to B) is _____ (negative), then the ∆G of backward reaction (B to A) is ______ (positive)

Answer 13

Exergonic, endergonic

Question 14

At equilibrium, ∆𝐺 is zero when forward reaction = _____

Answer 14

backward

Question 15

Hydrolysis is an example of what (give an example)

Answer 15

Exergonic reaction
ATP–> ADP + Pi

Question 16

If the ∆G of a reaction is zero:

a) The reaction is irreversible
b) The reaction is endergonic
c) The reaction is exergonic
d) The reaction is at equilibrium

Answer 16

D

Question 17

Consider the reactions of a biochemical pathway given below. What is the ∆G of the overall reaction conversion of A to D?
A–> B–> C–> D
A–> B delta G= -12.3 kcal/mol
B–> C delta G= 8.4 kcal/mol
C–> D delta G= -5.6 kcal/mol

Answer 17

9.6 kcal/mol

Question 18

Where is the ETC located?

Answer 18

Inner mitochondrial membrane

Question 19

Sources that generate FADH2

Answer 19

TCA cycle → Succinate dehydrogenase
β- oxidation of fatty acids → Acyl CoA dehydrogenase

Question 20

Sources that generate NADH

Answer 20

Glycolysis: Glyceraldehyde-3-phosphate dehydrogenase
Pyruvate dehydrogenase

TCA cycle: Isocitrate dehydrogenase, α-Ketoglutarate dehydrogenase, Malate dehydrogenase

β-Oxidation: β-hydroxyacyl CoA dehydrogenase

Question 21

How does NADH enter the mitocondria?

Answer 21

Malate-aspartate shuttle
Glycerol-3-phosphate shuttle

Question 22

Where does the malate-aspartate shuttle take place?

Answer 22

Liver and heart muscles

Question 23

How much ATP is yielded from the malate-aspartate shuttle ?

Answer 23

3

Question 24

Where does the glycerol-3-phosphate shuttle take place?

Answer 24

Brain and skeletal muscle

Question 25

How much ATP is yielded from the glycerol-3-phos shuttle ?

Answer 25

2

Question 26

Describe the steps of malate-aspartate shuttle

Answer 26

1) OAA gets converted to malate in the cytosol
2) malate enters the mitochondria and gets reconverted to OAA
3) This conversion produces NADH that will go to Complex 1
4) OAA binds with glutamate and this gives off aspartate and alpha-ketoglutarate
5) Aspartate leaves the mitochondria and binds with alpha- ketoglutarate in cytosol and becomes OAA and glutamate
6) The OAA starts cycle again

Question 27

Describe the steps of glycerol-3-phosphate

Answer 27

1) dihydroxacteone becomes glycerol-3-phosphate (NADH becomes NAD+)
2) G-3-P enters the mitochondria and gets converted back to DHAP
-this produces FADH2 from FAD which goes to complex 2

Question 28

What is another way that FADH2 enters the cell?

Answer 28

Fatty acyl CoA—> Enoyl CoA by the enzyme Acyl CoA DH

Question 29

Which complexes act as proton pumps?

Answer 29

Complexes I, III and IV act as proton pumps

Question 30

What are the mobile carriers of the ETC?

Answer 30

Coenzyme Q (also called as Ubiquinone)
Cytochrome c

Question 31

True or false. Complex 1 and 2 are dependent on each other

Answer 31

False

Question 32

Which compound is the last electron acceptor?

Answer 32

O2

Question 33

What’s another name for complex 1?

Answer 33

NADH CoQ reductase/NADH dehydrogenase

Question 34

What’s another name for complex 2?

Answer 34

Succinate CoQ reductase

Question 35

What’s another name for complex 3?

Answer 35

Cytochrome reductase

Question 36

What’s another name for complex 4?

Answer 36

Cytochrome oxidase

Question 37

What are the 2 subunits of ATP synthesis?

Answer 37

Fo- proton channel
F1- catalyzes ATP synthesis

Question 38

Draw the ETC pathway

Question 39

What inhibits complex 1 ?

Answer 39

Rotenone

Question 40

What inhibits complex 3?

Answer 40

Antimycin

Question 41

What inhibits complex 4?

Answer 41

CO and cyanide

Question 42

What inhibits ATP synthase?

Answer 42

Oligomycin and thermogenin (causes heat)

Question 43

What inhibits the uncoupling agent?

Answer 43

2,4-DNP

Question 44

Effects of tissue hypoxia

Answer 44

-decreases the rate of ETC and formation of ATP.
-Demand for ATP by the cells -↑rate of glycolysis-↑production of lactate (lactic acidosis).

Question 45

If ETC were inhibited, what will happen?

Answer 45

Decrease O2 consumption
Increase intracellular NADH/NAD
Decrease ATP levels

Question 46

Where is thermogenin found?

Answer 46

Brown Adipose Tissues (in infants)

Question 47

What are uncouplers?

Answer 47

They allow the protons to leak back into the matrix dissipating the proton gradient. Electron transport chain can no longer form a proton gradient, and ATP synthase can no longer make ATP