1. Completing the Cellular respiration picture
The ETC

2. Learning goals
We are learning to explain how electrons aid in the synthesis of ATP.
We are learning to understand the final products of aerobic respiration.

3. 3. ETC
Purpose: to use the energy stored in the H+ ions to resynthesize ATP
at this point, all the carbon from the original glucose molecule has been expelled as CO2
(2 during conversion to acetyl-CoA, 4 during Kreb’s)
thus, the only remaining part of glucose are the H’s that have been removed along the way and carried (by NAD and FAD) to the mitochondria

4. BACKGROUND INFO: MITOCHONDRIAL STRUCTURE
to understand the ETC, we need to understand the unique structure of the mitochondria:
2 membranes (inner & outer) separate the MATRIX from the “inter membrane space”

5. DEFINITIONS: OXIDATION VS. REDUCTION
oxidization - when a molecule loses hydrogens or electrons (and the E! they carry)
reduction - when a molecule gains hydrogens or electrons (and the E! they carry)
example: NAD and FAD are reduced during the Krebs, citrate is oxidized
OIL RIG

6. HYDROGEN CARRIERS VS. ELECTRON CARRIERS
hydrogen carriers - transport H’s (which contain energy in the form of electrons) e.g. NAD & FAD
electron carriers/protein complexes - transport electrons (removed from the H atoms)

7. Let’s draw it!

8. STEPS OF THE ETC
NADH+H and FADH2 lose their H atoms inside the mitochondrial matrix (i.e., NADH+H & FADH2 become “oxidized”)
The electrons from the H atoms are removed and passed to the first of 3 electron carriers. The 3 electron carriers have slightly different E! levels (1st has the highest)
As the electrons are passed from one electron carrier to the next, the ‘extra’ E! is released. This energy is used to ‘pump’ the remaining H+ protons across the inner membrane.

9. the chain, the E! released moves H+ ions across the inner membrane
as e-’s are passed down
the chain, the E! released
moves H+ ions across
the inner membrane
NOTE: FAD doesn’t
drop off its e-’s until
2nd carrier, which explains
why it’s not quite as good
at making ATP

10. The H+ protons start to build up between the inner & outer membrane, creating an H+ gradient (i.e., H+ protons want to move from area of high concentration to low)
Since inner membrane is impermeable, H+ protons can only pass through a specialized channel, called ATP synthase
As the H+ protons pass, they provide the E! required to fuse ADP and Pi back together

11. H+ ions want to move to area of lower concentration
H+ gradient forms, so
H+ ions want to move to area of lower concentration
as H+ pass through ATP Synthase, it spins, forcing ADP & phosphate back together

12. Once back in the matrix, the H+ protons recombine with their electrons and are eventually combined with oxygen (to make water) (i.e., oxygen becomes “reduced”)
this explains why we need to breathe in oxygen when we exercise (no oxygen = no H+ ‘pick up’ = no gradient = no ETC)

13. H+ combines with oxygen to make water

14. ACETYL-COA CONVERSION
PROCESS
NADH+H
(3 ATP per)
FADH2
(2 ATP/per)
ATP
GLYCOLYSIS 2 -
ACETYL-COA CONVERSION
KREBS CYCLE 6
TOTAL
10 X 3 ATP
2 X 2 ATP
TOTAL ATP PER GLUCOSE 30 4

15. Learning goals
We are learning to explain how electrons aid in the synthesis of ATP.
We are learning to understand the final products of aerobic respiration.