| Term | Description | SeeAlso |
| V Segment | Antibodies are created by the stochastic (random) splicing of three different gene sequences: a V Segment, a J Segment, and a D Segement. In this way, the immune system can create many different antibodies. Note that the joining of the V, J, and D segment is somewhat sloppy, resulting in even more mutations and variations in antibodies. | Antibody, Antigen |
| Vacuole | A small, membrane-bound cavity that is used by the cell for storage. Vacuoles are used for storing water, food, or metabolic waste. The membranes of vacuoles are typically made from a lipid bilayer. | Lipid, Vesicle, Lipid |
| Vector | A scientist, wishing to insert some foreign DNA into a cell (thus "transforming" the cell), uses a stretch of DNA called a "vector" to do this. This stretch of DNA has replication initiation sites ("origins of replication", so that the inserted DNA can be replicated). Episomes are good candiates for vectors in bacteria. | DNA Cloning, Transform, Episome |
| Vesicle | a small, membrane-bound, bubble-like container that is used for storage and transport within the cytoplasm of the cell. For example, the Golgi Apparatus uses vesicles to store proteins. The membrane of the vesicle is created by a lipid bilayer. | Lipid, Golgi Apparatus, Vacuole, Cytoplasm, Protein |
| Viral Tropism | The specificity of a virus for a particular cell type. Viruses typically invade a cell through a particular receptor, exhibiting a "tropism" ("facing towards") for that particular cell type. For example, the HIV virus has a tropism for T Helper Cells which have the CD4 receptor which the virus attaches to. | AIDS, CD4 |
| Virion | A virus particle. | Virus |
| Virus | A sub-cellular particle that don't have their own energy metabolism and that parasitize the macro-molecular machinery of a cell so that they can grow and reproduce. The virus enters a cell by "fooling" a receptor on the cells surface. The virus carries a genome, which can be either DNA or RNA. If the genome consists of RNA, the virus will bring Reverse Transcriptase (a protein) into the cell. Some viruses are cytopathic (causing cell death, lysis), while others are not. Viruses generally have a lipid-bilayer cell membrane encapsulating a protein capsid with an RNA or DNA genome (single or double-stranded) and some specialized proteins (e.g. integrase, reverse transcriptase). The layer of plasma membrane is often taken from an infected cell and added to the virion as it is pushed out of the infected cell | DNA, RNA, Lysis, Integrase, Reverse Transcriptase |