What is the name for the protein coat surrounding a virus?

The correct answer is "Capsid." The capsid is the protein coat that surrounds and protects the genetic material of a virus. It plays a critical role in the virus's ability to infect host cells, as it not only serves as a protective layer but also helps in recognizing and attaching to host cells. The structure of the capsid can influence the virus's shape and stability, which are important for its infectious properties.

The genome refers to the complete set of genetic material within a virus, which can be DNA or RNA, but it is not the outer protective layer. The envelope is an additional lipid layer that surrounds some viruses and helps them enter host cells, but not all viruses have an envelope, making the capsid a universal feature. A cell wall is a structure found in plant cells, bacterial cells, and fungi, providing structural support; it is unrelated to viruses, which do not have cell walls since they are not classified as living cells.