Energy Transfer In The Body Flashcards
What is ATP?
The only usable form of energy in the body.
What is ATP made of?
Energy from foods is broken down and is used to form ATP.
It’s 1 molecule of adenosine and 3 phosphates
How is energy released?
By breaking down the bonds that hold ATP together.
How is ATP broken down?
The enzyme ATP-ase
This leaves ADP - adenosine di-phosphate - and an inorganic phosphate (Pi).
How do we get ATP back?
The body has to constantly rebuild ATP by converting the ADP and Pi back into ATP.
We can re-synthesise ATP from 3 different types of chemical reaction in the muscle cells; these are fuelled by either food or a chemical called phosphocreatine
What are the energy systems?
Aerobic
ATP-PC
Anaerobic glycolytic
When is the aerobic system used?
When exercise intensity is low and oxygen supply is high (jogging), its the preferred energy pathway.
What are the stages of the aerobic system?
Glycolysis
Krebs cycle
Electron transport chain
What is glycolysis?
The breakdown of glucose into pyruvic acid.
What happens in glycolysis?
The first stage is anaerobic so it takes place in the sarcoplasm of the muscle cell.
For every molecule of glucose undergoing anaerobic glycolysis, a net of two molecules of ATP is formed.
What happens before the Krebs cycle?
Before the pyruvic acid produced in glycolysis can enter the next stage, it splits into two acetyl groups
It is then carried into the Krebs cycle by coenzyme A.
What is the Krebs cycle?
A series of chemical reactions that take place using oxygen in the matrix of the mitochondria.
What happens in the Krebs cycle?
Acetyl coenzyme A diffuses into the matrix of the mitochondria and a complex cycle of reactions occur
The acetyl coenzyme A combines with oxaloacetic acid, forming citric acid.
Hydrogen is removed from the citric acid and the rearranged form of citric acid undergoes oxidative carboxylation (carbon and hydrogen are given off).
The carbon forms carbon dioxide which is transported to the lungs and breathed out.
The hydrogen is taken to the electron transport chain.
The reaction produces 2 molecules of ATP.
What happens if fat enters the Krebs cycle?
Stored fat is broken down into glycerol and free fatty acids for transportation by the blood.
These fatty acids then undergo a process called beta oxidation, whereby they are converted into acetyl coenzyme A, which is the entry molecule for the Krebs cycle.
From this point on, fat metabolism follows the same path as glycogen metabolism.
More ATP can be made from 1 mole of fatty acids than 1 mole of glucose, which is why in long-duration, low-intensity exercise, fatty acids will be the predominant energy source - but this does depend on the fitness of the performer.
What is beta-oxidation?
A process where fatty acids are broken down to generate acetyl-CoA, which enters the Krebs cycle.