FIGURE 7-2 Eukaryotic cellular membranes are dynamic structures. (a) An electron micrograph of the plasma membrane of an HIV-infected cell, showing HIV particles budding into the culture medium. As the virus core buds from the cell, it becomes enveloped by a membrane, derived from the cell’s plasma membrane, that contains specific viral proteins. (b) Stacked membranes of the Golgi complex with budding vesicles. Note the irregular shape and curvature of these membranes.

[Part (a) from W. Sundquist and U. von Schwedler, University of Utah; part (b) Biology Pics/Science Source.]