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.
A virus particle, also known as a virion, is essentially a nucleic acid (DNA or RNA) enclosed in a protein shell or coat. Viruses are extremely small, approximately 20 - 400 nanometers in diameter. The largest virus, known as the Mimivirus, can measure up to 500 nanometers in diameter.By comparison, a human red blood cell is around 6,000 to 8,000 nanometers in diameter. In addition to varying sizes, viruses also have a variety of shapes.iruses are unique in that they have been classified as both living and nonliving at various points in the history of biology. Viruses are particles that are capable of causing a number of diseases including cancer. They not only infect humans and animals, but plants and bacteria as well.