Some viruses have accessory structures htat help them infect their hosts. For ex., a __ surrounds the capsids of flu viruses and many othe viruses. These __, which are derived from the embranes of the host cell, contain hlost cell phospholipids and membrane proteins. They also contain __ and __ of viral origin. Some viruses carry a few viral enzyme molecules within their capsids.
- membranous envelope
- viral envelopes