4.2 (c)

Question 1

At the end of the citric acid cycle

Answer 1

• Most energy is Yeild from NADH and FADH2
• Electron transport chain extracts energy from these

Question 2

Electron transport chain

Answer 2

• Occurs in inner mitochondrial membrane
• ▪Facilitates transfer of e- from
  NADH and FADH2 to O2

▪Consists of 4 protein complexes
▪Complex I – NADH dehydrogenase
▪Complex II – Succinate dehydrogenase
(the only single peripheral membrane
protein)
▪Complex III – Cytochrome complex
▪Complex IV – Cytochrome oxidase

Question 3

Complex I

Answer 3

Complex I
(NADH Dehydrogenase)

▪Oxidizes NADH (loses e-)
into NAD+

▪Protons (H+) are pumped

across the membrane as e-
move through the complex

Question 4

Complex II

Answer 4

Complex II
(Succinate Dehydrogenase)

▪Oxidizes FADH2

into FAD+

▪e-is picked up by UQ

Question 5

Electron Shuttles

Answer 5

▪Flow of e- is facilitated by
2 mobile e

• shuttles
  ▪ Ubiquinone (UQ),
  hydrophobic and found in the
  core of the membrane, shuttles e- from Complex I and II to
  complex III
  ▪ Cytochrome
  c
  (cyt
  c), found in
  intermembrane space, shuttles e- from Complex III to
  Complex IV

Question 6

Complex III

Answer 6

▪e-transferred from UQ move to
Complex III

▪Complex III transfers the e-to
Cytochrome C —-> Complex IV

Question 7

Complex IV

Answer 7

▪e- are transferred from Cyt c to
complex IV
▪e- combine with H+ and an oxygen
atom to form water

▪Mvmt of e- drives the pumping of
more H+ across the cell membrane

Question 8

The driving force behind

Answer 8

▪Complexes I, III, and IV increase in electronegativity

▪The electronegative nature of O2 drives the
entire ETC

Question 9

Chemiosmosis

Answer 9

▪H+ concentration becomes much higher in the intermembrane space, this difference in
concentration is called a proton gradient, which drives ATP synthesis

▪The ability for cells to use the proton-motive force to do work is called chemiosmosis
▪The energy for chemiosmosis comes from the oxidation of NADH and FADH2 by the ETC

Question 10

ATP Synthase

Answer 10

▪The flow of H+ thru ATP Synthase powers ATP
synthesis

• Produces ATp via oxidative phospphorylation

▪34 ATP are produced per glucose in the ETC

Question 11

Uncoupling Electron
Transport and Chemiosmosis

Answer 11

▪When electron transport and ATP synthesis are
uncoupled, the energy that is released is not converted
to ATP energy

▪Instead, it is released as thermal energy (helps with
animals that hibernate by maintaining body
temperature), when H+ rush back across the inner
membrane without passing thru ATP Synthase

▪ Via Special uncoupling proteins

Question 12

Can Uncouple Electron Transport
and Chemiosmosis be a BAD thing?

Answer 12

• Can cause overheating
• Ingesting DNP reduces ATP synthesis, and cells respond by consuming stored fat
  more readily to lose weight