state that all viruses are non-cellular structures with a nucleic acid core (either DNA or RNA) and a capsid made of protein, and that some viruses have an outer envelope made of phospholipids

All viruses are non-cellular structures composed of a nucleic acid core, which can be either DNA or RNA, and a protein capsid that surrounds and protects the nucleic acid. Additionally, some viruses have an outer envelope made of phospholipids, which they acquire from the host cell membrane. This envelope often contains viral proteins that assist in infecting host cells.

All Viruses are Non-Cellular Structures with the following key components:

1. 1. Nucleic Acid Core: Contains either DNA (Deoxyribonucleic Acid) or RNA (Ribonucleic Acid), but not both, which serves as the genetic material.
   2. Capsid: A protein shell that encloses and protects the nucleic acid core from the environment. The capsid is composed of one or more types of proteins that repeat to form the structure.
   3. Outer Envelope (in some viruses): An additional lipid layer, primarily composed of phospholipids, which surrounds the capsid in certain types of viruses. This envelope is typically derived from the host cell membrane (e.g., plasma membrane, endoplasmic reticulum, Golgi complex, or nuclear membrane) during the virus’s exit from the host cell.

Key Points

• Viral Structure:
  • Nucleocapsid (Naked Viruses): Consists of a genome surrounded by a capsid.
  • Enveloped Viruses: Have an additional outer envelope surrounding the nucleocapsid, derived from host cell membranes.
• Capsid Function:
  • Protects the fragile nucleic acid genome from the environment.
  • Composed of one or a few proteins that repeat to form the structure due to the small genome size.
• Envelope (when present):
  • A lipid membrane derived from host cell membranes.
  • May include matrix proteins to connect the envelope to the capsid.