barm - a commercial leavening agent containing yeast cells; used to raise the dough in making bread and for fermenting beer or whiskey. yeast. yeast cake - small cake of compressed moist yeast. brewer's yeast - yeast used in fermenting beer. leaven, leavening - a substance used to produce fermentation in dough or a liquid. mother - a stringy slimy substance consisting of yeast cells and bacteria; forms during fermentation and is added to cider or wine to produce vinegar.
1 Viruses, on the other hand, do not have any cells. 2  Viruses are made up of a protein structure called a capsid. 3  Though this capsid contains the virus's genetic material, it lacks the features of a true cell, such as cell walls, transport proteins, cytoplasm, organelles, and so on. Viruses, on the other hand, do not have any cells. 2  Viruses are made up of a protein structure called a capsid. 3  Though this capsid contains the virus's genetic material, it lacks the features of a true cell, such as cell walls, transport proteins, cytoplasm, organelles, and so on.
In the appropriate cell, DNA viruses are able to program the cell to replicate the virus using the genes contained within the viral DNA genome. The extracellular form of a virus is known as a virion. For a DNA virus, the virion is composed of a set of DNA genes protected by a proteincontaining coat called a capsid.The coat is often characterized by regularity and symmetry in its structure and is capable of binding to and invading cells.ike all viruses, DNA viruses are small when compared to the cells they infect and as such are obligate intracellular parasites (parasites that can only replicate within cells).