Glycolysis

• ATP hydrolysed (ATP +$H_2O$)


  ATP +$H_2O$$\rightarrow$ADP + inorganic phosphate + 30.5 kJ
• 2 types of phosphorylation occur during respiration

  1. substrate-level: glycolysis and krebs cycle
  2. oxidative: electron transport chain
• phosphorylation


  addition of an inorganic phosphate group to a molecule like ADP
• coenzymes


  • molecules that bind with a specific enzyme or substrate, helping to catalyse a reaction by breaking bonds between coenzyme and product after reaction
• 3 major coenzymes used in respiration

  • NAD
  • Coenzyme A
  • FAD
• NAD


  • can accept a hydrogen molecule, forming reduced NAD (NADH)
  • $^{NAD^+}$+ 2H $\rightarrow$ NADH + $^{H^+}$
  • used to regenerate ADP in ECT ( electron transport chain)
• Coenzyme A


  • Aids transition between glycolysis and krebs cycle, by converting pyruvate to acetyl coenzyme A
• FAD


  • like NAD, can accept hydrogen to form reduced FAD (FADH2) - donate later to create ATP for ETC (electron transport chain)
• 10 reactions split into 3 sections 


  • phosphorylation
  • splitting
  • oxidation
• • the initial stage of respiration known as glycolysis, takes place in the cytoplasm of cells
  • glucose is a good source of energy, but is unreactive, so it requires an input of energy from ATP to get the reaction started
  • two phosphate groups are added to the glucose in a process called phosphorylation
• • after phosphorylation, glucose can be split into 2 3 carbon compounds. (TP)
  • Each 3C compound is then oxidised producing pyruvate. This is controlled by an enzyme - dehydrogenase
  • 2 ATP molecules can be produced in this process by each triose phosphate group
  • 2 hydrogen atoms are also removed by coenzyme NAD forming reduced NAD
• • glucose is at a higher energy level than the pyruvate and some of that energy becomes available for the formation of ATP
  • glycolysis reactions yield a net gain of 2 ATP, 2 pairs of hydrogen atoms and 2 molecules of 3C pyruvate
• glycolysis steps

  1. phosphorylation of glucose
  2. so forming hexose 1,6 biphosphate
  3. splitting into 2 TP
  4. formation of reduced NAD
  5. pyruvate produced from TP
  6. total production 4 ATP