Common ciliated eucaryotic unicellular organisms widespread in freshwaters.
paramecium caudatum, unicellular, unicellular eukaryotes, Ciliatea, cell organelle, contractile vacuole, cilia, digestive vacuole, cilium, cytostome, freshwater, Ciliophora, animal, biology
- contractile vacuole - It pumps excess water and waste materials out of the cell. In freshwater environments the concentration of solutes inside the cell is higher than outside the cell, therefore water flows from the environment into the cell by osmosis. The excess water needs to be removed by an energy-intensive process.
- cytostome - Food (organic debris, bacteria) enter the cell through it.
- cytopharynx - Food enters through the cytostome, then it is absorbed by endocytosis.
- cilia - Their rhythmic, coordinated whipping motions provide mobility for the cell and direct food towards the cytostome.
- micronucleus (generative) - It contains the cell's DNA, which is exchanged during sexual reproduction.
- macronucleus (vegetative) - Controls the cell's vegetative functions.
- digestive vacuole - Food is absorbed from the cytopharynx by endocytosis. Food granules are packed in membrane vacuoles, where they are digested.
Widespread heterotrophic unicellular organisms with constantly changing shapes
Unicellular eukaryotes living in freshwaters, capable of feeding autotrophically and heterotrophically.
Tardigrades can survive in extreme environments, they can even stay alive in outer space.
There are two basic cell types: prokaryotic and eukaryotic cells.
Eukaryotic cells contain a number of organelles.
Bacteria occur in a wide range of shapes, including spheres, rods and spirals.
Jellyfish are free-swimming marine animals, a species of Cnidaria, the most ancient group of Eumetazoans.
Eukaryotic cells with nuclei measuring only a few micrometres may contain nearly 2 metres of DNA, coiled multiple times.
Viruses consist of protein and DNA or RNA, they reprogram infected cells to produce more viruses.