RESPIRATION

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 - ) © 2010 Paul Billiet ODWSODWS

Energy transformations Light  Chemical (mostly in chemical bonds) Chemical  Heat Chemical  Kinetic (movement) Chemical  Chemical COUPLED REACTIONS e.g. Food  ATP © 2010 Paul Billiet ODWSODWS

The energy in Adenosine Triphosphate (ATP) ADP + Pi  ATP + H 2 O  E = kJ mol -1 Inorganic phosphate High energy bond ADENOSINE  P  P  P © 2010 Paul Billiet ODWSODWS

A stepwise energy release is needed Complete oxidation of glucose C 6 H 12 O 6 + 6O 2  6CO 2 + 6H 2 O  E = 2880 kJ mol -1 Complete oxidation of a fat (lipid) C 18 H 34 O O 2  18CO H 2 O  E = 9800 kJ mol -1 © 2010 Paul Billiet ODWSODWS

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 © 2010 Paul Billiet ODWSODWS

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) © 2010 Paul Billiet ODWSODWS