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.
1 By contrast, viruses generally carry information-for example, DNA or RNA, packaged in a protein and/or membranous coat. 2  They need the host cell's machinery to reproduce. 3  The legs of a virus attach onto the surface of the cell and then the genetic material contained inside the virus is injected into the cell. Bacteria are single-celled organisms that can live either inside or outside other cells. 2  They can survive without a cellular host. 3  Viruses, on the other hand, are only intracellular organisms, meaning that they infiltrate the host cell and live inside the cell.