What you should know from today’s lecture Energy and carbon sources in biology Autotrophs and heterotrophs Overall chemical reactions and sites of photosynthesis and respiration Common features of photosynthesis and respiration (electron transport; chemiosmotic formation of ATP) Uncouplers

What does life require? Energy – to do work Carbon – to make the physical structure

How do organisms acquire energy and carbon? Autotrophs –Carbon from CO 2 –Energy from sunlight – photoautotrophs –Energy from simple inorganic chemicals (e.g., hydrogen gas) – chemoautotrophs Heterotrophs –Carbon and energy from complex organic molecules (e.g., glucose)

Autotrophs and heterotrophs Photoautotrophs –Green plants –Algae –Some protists –Blue-green bacteria –Purple photosynthetic bacteria Chemoautotrophs –Archaea Heterotrophs –Animals –Fungi –Parasitic plants –Some protists –Most bacteria

Types of energy Used by humans: Gravitational (e.g., hydro, tidal) Kinetic (e.g., wind, waves) Geothermal Nuclear Solar Chemical (combustion of petroleum, coal, gas, wood, H 2 )  Often converted to electricity Used by cells: Chemical energy –Breaking of covalent bonds in complex molecules like glucose and ATP

6CO 2 + 6H 2 O  C 6 H 12 O 6 + O 2 glucose 54 ATP equiv. 36 ATP

Common features of photosynthesis and respiration Electron transport Chemiosmotic formation of ATP

Electron transport C ---- C V C --* *--C

Chemiosmotic formation of ATP Effect of uncouplers (e.g., 2,4- dinitrophenol)

Photosynthesis: the big picture Takes place in the chloroplasts of eukaryotes and in the membrane and cytoplasm of blue-green bacteria

Respiration: the big picture Takes place in the mitochondria of eukaryotes and in the membrane and cytoplasm of prokaryotes