prions Resembling viruses, these pathogens are composed only of protein, with no detectable nucleic acid.
prokaryotes Simple organisms with no cell nuclei and very few cell organelles.
protein Macromolecules whose structures are coded in an organisms DNA. Each is a chain of more than 40 amino acids folded back upon itself in a partic ular way.
proteolytic Capable of lysing (denaturing, or breaking down) proteins.
recombinant Containing genetic material from another organism. Genetically altered microorganisms are usually referred to as recombinant, whereas plants and animals so modified are called transgenic (see transgen ics).
restriction enzyme An bacterial enzyme that cuts DNA molecules at the location of particular sequences of base pairs.
ribosome Cell organelles that translate RNA to build proteins.
RNA Ribonucleic acid; similar to DNA but based on ribose, and with the base uracil (U) in place of thymine (T). Various forms of RNA are found: mRNA (messenger RNA); tRNA (transfer RNA); and rRNA (ribosomal RNA). Most RNA molecules are single-stranded, although they can form double-stranded units.
roller bottle A container with large growth surfaces in which cells can be
grown in a confluent monolayer. The bottles are rotated or agitated to keep
cells in suspension, but they require extensive handling, labor, and media. In
large-scale vaccine production, roller bottles have been replaced by microcar
rier culture systems that offer the advantage of scale-up