Hi everyone,
For cellular respiration, do I need to memorise the steps descibed bellow or just memorize what the inputs and outputs are for each stage?
Eg: in the electron transport chain do I need to memorise the following?
1 NADH and FADH2 unload electrons and protons at the first and second protein
complexes of the electron transport chain that reside in the inner mitochondrial
membrane. The following reactions take place:
(1) NADH NAD+ + H+ + 2 e–
(2) FADH2 FAD + 2 H+ + 2 e–.
2 The excited electrons (from NADH and FADH2) are transferred through a number
of different protein complexes embedded in the electron transport chain, powering
the active transport of protons (H+) from the mitochondrial matrix into the narrow
intermembrane space.
3 This leads to a build-up of protons in the intermembrane space. As this space is very
narrow and small, the proton concentration here quickly increases, creating a steep
concentration gradient across the inner mitochondrial membrane.
4 To move down their concentration gradient, these protons must travel through
the specialised protein channel ATP synthase. As the protons pass through ATP
synthase, they cause the enzyme to spin like a turbine. The kinetic energy of this
movement powers the reaction ADP + Pi ATP, producing 32 or 34 ATP for each
original glucose molecule.
5 This process produces large amounts of ATP, but also leads to many free protons
and electrons building up in the matrix. Unbound protons and electrons can cause
problems for cells in large concentrations – they can damage DNA, interfere with
enzyme reactions and create dysfunctional proteins. To prevent this from happening,
oxygen acts as the terminal acceptor, binding with these dangerous protons and
electrons to form harmless water. Oxygen is therefore required for the electron
transport chain to proceed.
Same with the kerbs cycle..
• By breaking down acetyl-CoA, protons and high-energy electrons are released.
These protons and electrons are loaded onto NAD+ and FAD molecules to generate
high-energy coenzymes NADH and FADH2.
• The Krebs cycle produces two CO2 molecules for every one acetyl-CoA molecule.
When added to the single CO2 molecule produced from each of the two pyruvates
undergoing the link reaction, this means a total of six CO2 molecules are produced
for every original glucose molecule.
• The Krebs cycle produces a small amount of energy in the form of two ATP (one per
acetyl-CoA molecule).
And for glycolysis...
• 2 ADP + 2 Pi 2 ATP
− The ATP is now free to power cellular reactions.
• 2 NAD+ + 2 H+ + 4 e− 2 NADH
− The electrons (two per NAD+) are often not written in this equation, but they are
necessary for the reaction to proceed.
− The H+ and electrons come from the breakdown of glucose.
− The two NADH molecules will be transported to the mitochondria, where each
molecule will deliver protons and electrons to the electron transport chain, to help
make more ATP. For this reason, we call NADH an ‘electron and proton carrier’.