metabolism 1

• catabolic reaction: for a cell to generate energy
• anabolic reaction: synthesise molecules
• coupled reaction: cell uses energy from catabolic to drive anabolic reactions
• 2 types of ATP production: substrate level phosphorylation and oxidative phosphorylation
• substrate level phosphorylation: no oxygen required, direct transfer of Pi to ADP
• oxidative phosphorylation: requires oxygen, needs energy from redox reactions to power ATP synthesis
• majority of ATP is formed by oxidative phosphorylation
• redox reaction: oxidation and reduction, coenzymes are involved
• coenzymes temporarily recieve E or H to facilitate chemical reactions
• coenzymes collect electrons (reduced) and deliver them to the mitochondria (where oxidised)
• NADH produces 2.5ATP
• FADH2 produces 1.5 ATP
• glycolysis occurs in the cytosol
• krebs cycle occurs in the mitochondrial matrix
• ETC occurs in the inner mitochondrial membrane
• glycolysis is important as: oxygen is not limiting, for RBC, fast production of ATP
• glycolysis first step: glucose enters cell via transport protein and is converted to G-6-P
• conversion to G-6-P requires hexokinase and ATP
• the conversion to G-6-P is only reversible in the liver
• Glut 4 is the transporter for skeletal and adipose tissue, it needs insulin to be activated
• after conversion into G-6-P, the molecule is cleaved into 2, creating fructose 1,6 bisphosphate
• the conversion into fructose 1,6 bisphosphate creates 2 3C molecules
• conversion from G-3-P requires ATP and NAD, from this 1NADH is reduced and 2 ATP is produced
• the presence or absence of oxygen in high enough amounts determines the fate of pyruvate
• if rate of oxidative phosphorylation is high, glycolysis may be used to meet energy requirements
• if o2 is a limiting factor, ATP must be produced by glycolysis, but this requires NAD
• if there is an absence of oxygen, pyruvate forms lactate and the NADH is oxidised to regenerate NAD to go through glycolysis
• the Cori Cycle is the production of lactate, forming pyruvate, forming glucose
• pyruvate can be transported from the cytosol into the mitochondria to form acetyl CoA
• PDH helps convert pyruvate to acetyl CoA, this requires NAD and CoA
• Carbs, fats, and amino acids can be metabolised to form CoA
• The Krebs cycle requires oxygen and happens in mitochondrial matrix
• the Krebs cycle produces 2 Co2, 3 NADH, 1 FADH2 and 1 ATP each cycle with a total of 2 cycles
• the first step of the Krebs cycle is OAA + Acetyl CoA = citric acid
• collected electrons from glycolysis, pyruvate and the Krebs cycle go to the ETC
• in the ETC, NADH is oxidised to NAD and FADH2 is oxidised to become FAD, the donated electrons move through the complexes to reach the oxygen, that recieve them to make h2o
• energy produced by ETC initiates proton pump and protons are pumped into IMM and cannot reenter, matrix becomes negative and IMM becomes positive, protons can then reenter to form ATP through the ATP synthase by donating a phosphate
• oxygen is the final electron acceptor, if it is not present, ATP productio cannot continue
• ETC produces 32-34 ATP
• glycolysis is 10 reactions