As we learn more about specific microbes, they will become indispensable. For each such description, be able to identify how the organism obtains its C and its energy. We'll come back later to how organisms acquire S, P, and N. skim this section on p. 100. Note that, although facilitated diffusion is common inside the animal body, it is not common in procaryotes. Considering that bacteria are unicellular and have little control of their environment, suggest a reason why active transport mechanisms are preferred.
Many bacteria use ion gradients to power active transport with a number of carriers.
Ion gradients can be coupled either in symport or antiport fashion. Yet another way of powering active transport is group translocation . Instead of ATP or ion gradients, a different molecule with high-energy phosphate provides initial activation energy that is ultimately coupled to entry of substrate with accompanying phosphorylation. The PTS system in E. coli is a common example, though by no means an isolated one. Be able to recognize and distinguish this type of transport from those mentioned above.