All organisms on Earth are divided into two large groups - cellular and non-cellular. The latter include only viruses, and the former include all other living beings. Cells can be eukaryotes (they have a nucleus in the cell structure) or prokaryotes (there is no nucleus). The latter are represented by bacteria, and the former include all other groups of creatures. The structure of most of them consists of many cells, but there are unicellular organisms, plants, fungi and even animals in this group. The latter include amoeba, infusoria, and fungi - yeast, mucor, penicillium.
Structure of cells of unicellular plants
These organisms are eukaryotes, that is, their DNA is located in the nucleus, which performs a protective function. Like all plant cells, they contain specific organelles such as vacuoles and plastids. Also, their structure includes mitochondria, lysosomes, ribosomes, the Golgi complex and the endoplasmic reticulum, that is, a set of organelles that is standard for all eukaryotes.
Functions of organelles
Mitochondria perform one of the most important roles in the cell - they produce energy for all life processes. Lysosomes are responsible for intracellular digestion of nutrients. The functions of ribosomes are to synthesize proteins from individual amino acids.
Some molecules are synthesized in the Golgi complex and all substances produced by the cell are sorted.
The endoplasmic reticulum is also involved in metabolism, accumulating minerals, synthesizing lipids and phospholipids. Organelles, which are unique to plant cells, also perform equally important functions. In chloroplasts, the process of photosynthesis takes place, and vacuoles act as a reservoir for substances that are unnecessary to the cell.
Single-celled plants. Examples
This kind of organism belongs to the class of algae. The most striking example of a single-celled plant is Chlamydomonas. This also includes chlorella and various types of diatoms.
Building features
Single-celled plants of different species have their own distinctive features. Although they all consist of one cell, they may have their own specific features.
Chlamydomonas is the most famous representative of unicellular algae. They differ from others in that they have organelles such as a light-sensitive eye, with which organisms can determine where there is more solar energy for photosynthesis. Instead of numerous chloroplasts, they have one large one called a chromatophore. They also contain contractile vacuoles. They act as pumps that pump out excess fluid. Besides,they have two flagella-organelles that allow the body to move towards the light. Another unicellular plant is chlorella.
Like Chlamydomonas, they are green algae, but do not have as many special organelles as the organisms described above. Their cells are typical plant cells.
Diatoms are also unicellular plants. They are the main component of plankton living in large water bodies. They have a specific cell membrane that protects the body from the external environment. It consists of silicon dioxide, oxides of iron, aluminum and other compounds. Many minerals are formed from the remains of these shells. Most unicellular plants reproduce by division. All such organisms obtain their nutrients in the process of photosynthesis, that is, they are autotrophs.
