Respiration

DNA

Cristae

Outer membrane

Inner membrane 

Matrix 

Comparmentalization= some organisms contain membrane bound organelles. The membranses surrounding the organelles serve as barriers dividing the cell into seperate compartments. 

• Glycolysis= + 2 ATP    
• Link reaction= + 2 reduced NAD and releases 2 carbon dioxide 
• Krebs cycle= + 2 ATP 
• Oxidative phosphorylation/ Electron transfer chain = + 34 ATP

• Converts 6C glucose into 3C pyruvate 
• Occurs in cytoplasm 
• An anaerobic process 
• Glucose is split into two seperate triose sugars, this is done by the energy gained from the phosphrylation of 2 ATP. This forms two triose phosphate molecules 
• Each of the triose sugars are then oxidised by inorganic phosphates which in turn reduces the co enzyme NAD, as it gains electrons, creating 2X reduced NAD
• These triose sugars are then converted into pyruvate in this process, for each triose sugar 2 ADP molecules are phosphorylated into 2 ATP molecules .                                                    This is called SUBSTRATE LEVEL PHOSPHORYLATION
• Creates 4 ATP molecules with a net gain of 2 ATP 

• Also the first part of anaerobic respiration 
• In yeast the pyruvate is converted into ethanol and carbon dioxide and in mammals it's converted into lactic acid 
• This allows the regeneration of reduced NAD into NAD which is needed for the production of more pyruvate 
• This also has a gross gain of 4 ATP and a net gain of 2 ATP

• Pyruvate leaves the cytoplasm and enters the matrix of the mitochondria 
• The 3 carbon pyruvate goes through decarboxylation where it loses a a carbon as carbon dioxide
• At the same time the coenzyme NAD removes hydrogen from the pyruvate oxidising the pyruvate and reducing the NAD.
• This reaction is catalysed by an OXIREDUCTASE ENZYME ( dehydrogenate) .
• The two carbons left from the pyruvate then combine with Coenzyme A to produce ACETYL COENZYME A.
• Acetyl coenzyme A can be formed from both carbohydrates and fatty acids. 

• Occurs in matrix of the mitochondria 
• One ADP is phosphorylated into ATP and two carbon dioxides are produced 
• Four coenzymes are released 

• 2 Carbons from Acetyl coenzyme A join with a four carbon compound to form the six carbon compound (citrate) 
• In a series of reactions the 6C compound is converted back into the 4C compound.
• During this 3 NAD's become reduced as well as FAD. Both of these reductions are catalysed by an oxireductase enzyme
• One ADP is also phosphorylated into ATP 

Cytochrome= Protein that contains iron in a haem group. The iron is easily oxidised and reduced.

Electron transfer chain= compounds (e.g.cytochromes) transfer electrons from electron donors to electron acceptors by redox reactions. They couple this with the transfer of protons across a membrane.

• The reduced NAD and FAD pass their hydrogens and electrons to a chain of cytochrome carriers which are foudn in the cristae of the mitochondria. 
• This process seperates the hydrogen and electrons creating a proton gradient across the membrane. 
• The space between the inner and outer membrane has a low pH due to the acumulation of H ions. 
• Protons flow down and electrochemical gradient through ATP synthase. This movement powers ATP synthase which synthesis ADP + Pi to create ATP 

• Each NAD generates 3 ATP molecules 
• Each FAD generates 2 ATP molecules
• One turn of the respiration cycle forms 38 ATP, 
• the actual amount tends to be 30-32 however as there can be a leakage of protons and other molecules.

ATP is formed by 

• Substrate level phosphorylation- exergonic reaction of TP into pyruvate or the conversions of ketoglutarate into succinate in the krebs cycle. always anaerobic and only in respiration.
• Oxidative phosphorylation- ATP formed on the mitochondrial cristae, with energy from the oxidation of hydrogen. Alwasy aerobic.
• Photophosphorylation- ATP formed on the granal lammelae in the chloroplast. Energy supplieed by sunlight. This is anaerobix