<Tr> <Td> Sodium </Td> <Td> 12 </Td> <Td> 145 </Td> </Tr> <Tr> <Td> Chloride </Td> <Td> 4 </Td> <Td> 116 </Td> </Tr> <Tr> <Td> Bicarbonate </Td> <Td> 12 </Td> <Td> 29 </Td> </Tr> <Tr> <Td> Amino acids in proteins </Td> <Td> 138 </Td> <Td> 9 </Td> </Tr>

Where does most of metabolic activity in a cell occur