A cell is a holistic system where each component is interconnected with another. This interconnection of organoids ensures the ordering of the cell as a system. The cell membrane separates the cell from the external environment, it is strong, it includes cellulose (in plants), chitin (in fungi). The cell membrane gives shape, and serves not just as a mechanical skeleton. The membrane is involved in the absorption and excretion of cell substances, being an anti-infection barrier. An animal cell has no cell membrane; it has a cytoplasmic membrane. Any organism is characterized by all the signs of a living: metabolism and energy conversion, growth, development and reproduction, heredity and variability. The cell has all these properties.
Metabolism and energy – carried out at the cellular level – is the synthesis of proteins, lipids, carbohydrates, nucleic acids due to special organoids: ribosomes, lysosomes, Golgi complex, mitochondria.
Growth, reproduction, heredity and variability – due to cell division – mitosis, meiosis – is carried out using the nucleus, DNA, or nucleoid (in prokaryotes).
Remember: The process of learning a person lasts a lifetime. The value of the same knowledge for different people may be different, it is determined by their individual characteristics and needs. Therefore, knowledge is always needed at any age and position.