RESPIRATION © 2016 Paul Billiet ODWS

Energy in food Carbohydrates (17 kJ g-1) Proteins (17 kJ g-1) Lipids (34 kJ g-1) These are sources of reduced carbon This can supply hydrogen atoms  protons (H+) + electrons (e-). © 2016 Paul Billiet ODWS

Energy transformations Light  Chemical (mostly in chemical bonds) Chemical  Heat Chemical  Kinetic (movement) Chemical  Chemical COUPLED REACTIONS e.g. Food  ATP. © 2016 Paul Billiet ODWS

The energy in Adenosine Triphosphate (ATP) ADP + Pi  ATP + H2O E = + 30.5 kJ mol-1 Inorganic phosphate ADENOSINE  P  P  P High energy bond © 2016 Paul Billiet ODWS

A stepwise energy release is needed Complete oxidation of glucose C6H12O6 + 6O2  6CO2 + 6H2O E = 2880 kJ mol-1 Complete oxidation of a fat (lipid) C18H34O2 + 25.5O2  18CO2 + 17H2O E = 9800 kJ mol-1 © 2016 Paul Billiet ODWS

Respiration is efficient This is too much to handle all at once Energy is released step by step Coupled to ATP synthesis The energy in 1 molecule of glucose is used to synthesise 36 molecules of ATP 37.5 % efficient This is a very efficient energy conversion Because the release of the energy from the food molecules is done stepwise © 2016 Paul Billiet ODWS

Coupling the energy released from glucose to ATP Two reaction pathways GLYCOLYSIS in the cytoplasm KREB'S CYCLE in mitochondria of eukaryotes (in the cytoplasm of prokaryotes). © 2016 Paul Billiet ODWS