<Tr> <Td> Electron donor </Td> <Td> organic compound </Td> <Td> </Td> <Td> organo - </Td> <Td> </Td> </Tr> <Tr> <Td> inorganic compound </Td> <Td> litho - </Td> </Tr> <Tr> <Td> Carbon source </Td> <Td> organic compound </Td> <Td_colspan="2"> </Td> <Td> hetero - </Td> </Tr> <Tr> <Td> inorganic compound </Td> <Td> auto - </Td> </Tr>

Where do most metabolic reactions take place in a cell