Viral envelopes are typically derived from which structure of the host cell?

Viral envelopes are typically derived from which structure of the host cell?

• A. Cytoplasm
• B. Phospholipid bilayer of the plasma membrane
• C. Nuclear envelope
• D. Ribosome

Answer: (B)

Enveloped viruses get their lipid envelope from a host cell membrane as they exit. During budding, the virus borrows a portion of the host’s phospholipid bilayer, typically the plasma membrane, and incorporates viral glycoproteins into that membrane to form the envelope. This makes the envelope a host-derived lipid layer that surrounds the viral capsid. The other options aren’t sources of a lipid envelope: the cytoplasm is the interior of the cell, not a boundary; the nuclear envelope is a membrane around the nucleus and viruses usually bud from the plasma membrane rather than exiting through the nucleus; ribosomes are protein-synthesis sites, not membranes.

Enveloped viruses get their lipid envelope from a host cell membrane as they exit. During budding, the virus borrows a portion of the host’s phospholipid bilayer, typically the plasma membrane, and incorporates viral glycoproteins into that membrane to form the envelope. This makes the envelope a host-derived lipid layer that surrounds the viral capsid. The other options aren’t sources of a lipid envelope: the cytoplasm is the interior of the cell, not a boundary; the nuclear envelope is a membrane around the nucleus and viruses usually bud from the plasma membrane rather than exiting through the nucleus; ribosomes are protein-synthesis sites, not membranes.