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How leaky were primitive cells?

2008; Nature Portfolio; Volume: 454; Issue: 7200 Linguagem: Inglês

10.1038/454037a

1476-4687

David W. Deamer,

Photosynthetic Processes and Mechanisms

If the first cells were simple vesicles, how did nutrients cross their membranes without help from transport proteins? A model of a primitive cell suggests that early membranes were surprisingly permeable. The phospholipids that form the membranes of modern cells present a formidable barrier to polar and charged molecules, necessitating complex channels and pumps to permit the exchange of molecules with the external environment. This presents a problem when trying to imagine what a primitive cell would have looked like earlier in the evolution of life. With no transport machinery, how could simple cells take in complex nutrients? A possible answer comes in the form of a model 'protocell' produced by a team at Harvard. Fatty acids and their derivatives are attractive candidates as components of early protocell membranes as they are simple amphiphiles that form bilayer membrane vesicles. A proto-cell equipped with such a membrane is found to be able to take in charged molecules such as nucleotides, while retaining longer genetic polymers made from them inside.