Harvesting Chemical Energy Flashcards
What is the ATP cycle?
The transfer of energy between complex and simple molecules in the body, with ATP as the mediator
Fuel is needed to generate ATP, what are the major categories of fuel?
- Carbohydrates: broken down to simple sugars
- Proteins: break down to amino acids
- Fats: broken down to simple fats
What is Cellular respiration?
It is the controlled release of energy from organic compounds to produce ATP
What are the 4 main steps of Conversion of glucose to ATP?
- Glycolysis
- Pyruvate oxidation
- Citric acid cycle (or krebs cycle)
- Electron transport chain
What does the first step of Glycolysis do?
Invests and produces ATP - but not much.
Occurs in the cytosol and oxygen is NOT required.
Two ATP are invested –> Four ATP are produced
Two ATP and 2NADH are produced.
What is step 2 of Pyruvate oxidation?
It forms Acetyl CoA which links glycolysis to the citric acid cycle.
Occurs in the mitochondrial matrix and oxygen IS REQUIRED. Produced no ATP, but produces 1 NADH per pyruvate ( or 2 per glucose) plus 1 CO2.
The acetyl CoA enables the 2-carbon acetyl group to enter the citric acid cycle
What is step 3 of the Citric acid cycle?
Occurs in the mitochondrial matrix.
Results in:
2 ATP
6 NADH
2 FAFH2
4 CO2
(Per glucose molecule)
Requires oxygen - it is an aerobic process
(FADH2 and NADH are electron donors in the electron transport chain
What is substrate phosphorylation
ATP generated by direct transfer (from a substrate) of a phosphate group to ADP.
Glycolysis and Citric acid cycle make ATP via substrate phosphorylation
What is oxidative phosphorylation?
ATP is generated from the oxidation of NADH and FADH2 and the subsequent transfer of electrons and pumping of protons
What is step 4 of the electron transport chain?
Occurs at proteins within the inner membrane.
Requires oxygen - it is an aerobic process.
NADH and FADH2 are oxidised to donate electrons.
Electrons transfer from protein-to-protein along the chain in a series of redox reactions
At each transfer, each electron gives up a small amount of energy which enables H+ ions to be pumped into intermembrane space.
Oxygen pulls the electrons down the chain, and is then the final electron acceptor where it is reduced to water
What is the step 4 continue onto?
Chemiosmosis.
The hydrogen ions in the intermembrane space rush down their concentration gradient (Chemiosmosis) through ATP synthase. This causes the “turbine” within ATP synthase to turn.
The rotation of the ATP synthase turbine enables the phosphorylation of ADP to generate ATP.
This results in the production of 26 or 28 ATP (per glucose)
Step 4: ETC and chemiosmosis = ?
Oxidative phosphorylation.
The bulk of ATP production occurs here.
“Fall” of electrons down the chain enables
movement of H+ ions into intermembrane
space and generates a proton gradient
which “drives” the ATP synthase turbine.
Oxygen is REQUIRED. Oxygen is the final electron acceptor - cyanide blocks passage of electrons to O2 = death of cell
Putting all the steps from 1 (Glycolysis) to 4 (Electron transport chain) will make the?
Cellular respiration
Is Cellular respiration versatile?
Yes! It can derive energy from more than just glucose. Fats, proteins and more complex carbohydrates generate ATP also.
Monomers enter glycolysis and the citric acid cycle at different points.
What is phosphofructokinase?
a rate-determining enzyme of glycolysis, is an allosteric enzyme that regulates the oxidation of glucose in cellular respiration.
Inhibited by citrate and ATP. I.e products of cellular respiration
Stimulated by AMP which accumulates when ATP is being used rapidly
