Paramecium: A genus of ciliate protozoa that is often large enough to be seen by the naked eye. Paramecia are commonly used in genetic, cytological, and other research.Paramecium tetraurelia: A species of ciliate protozoa. It is used in biomedical research.Paramecium caudatum: The most widely distributed species of PARAMECIUM. It is elongated and possesses a bluntly pointed posterior.Paramecium aurelia: A species of ciliated PARAMECIUM possessing two micronuclei.Cilia: Populations of thin, motile processes found covering the surface of ciliates (CILIOPHORA) or the free surface of the cells making up ciliated EPITHELIUM. Each cilium arises from a basic granule in the superficial layer of CYTOPLASM. The movement of cilia propels ciliates through the liquid in which they live. The movement of cilia on a ciliated epithelium serves to propel a surface layer of mucus or fluid. (King & Stansfield, A Dictionary of Genetics, 4th ed)Chlorella: Nonmotile unicellular green algae potentially valuable as a source of high-grade protein and B-complex vitamins.Genes, Protozoan: The functional hereditary units of protozoa.Macronucleus: The larger of two types of nuclei in ciliate protozoans. It is the transcriptionally active nucleus of the vegetative cells as distinguished from the smaller transcriptionally inert GERMLINE MICRONUCLEUS.Micronucleus, Germline: The smaller, reproductive, transcriptionally inert nucleus in the cells of ciliate protozoans, as distinguished from the larger, vegetative, transcriptionally active MACRONUCLEUS. Micronuclei participate in MEIOSIS and autogamy during GENETIC CONJUGATION.DNA, Protozoan: Deoxyribonucleic acid that makes up the genetic material of protozoa.Phycodnaviridae: A family of DNA plant viruses that infect eukaryotic algae.Genome, Protozoan: The complete genetic complement contained in a set of CHROMOSOMES in a protozoan.Protozoan Proteins: Proteins found in any species of protozoan.Ciliophora: A phylum of EUKARYOTES characterized by the presence of cilia at some time during the life cycle. It comprises three classes: KINETOFRAGMINOPHOREA; OLIGOHYMENOPHOREA; and POLYMENOPHOREA.Exocytosis: Cellular release of material within membrane-limited vesicles by fusion of the vesicles with the CELL MEMBRANE.Holosporaceae: A family of bacteria comprised of endosymbionts of protozoa.Organoids: An organization of cells into an organ-like structure. Organoids can be generated in culture. They are also found in certain neoplasms.