It also serves as an attachment. It basically allows the virus to attach onto living cells. So the lipid code can have receptor proteins that can recognize and bind to other living cells and in fact, those living cells. Now, as I mentioned earlier viruses cannot actually reproduce on their own and this is because they did not contain the proper machinery to actually reproduce and create the molecules needed for reproduction and division. For example, viruses do not have ribosomes and that means they cannot themselves produce proteins. However, instead of actually replicating and dividing on their own our viruses can actually infect living cells and use the machinery, the organelles of the living cells to actually reproduce and divide and form other viruses.