Every living thing is made up of cells, including the human body, which contains billions of cells with different functions. Cells are tiny functional units that show independent living characteristics.
Structure of cells
Cells are separated from the environment by a thin cell membrane, which encloses a gelatinous substance, the cytoplasm. In addition to many other tiny cell organelles, every cell contains a nucleus, which is also surrounded by a thin membrane called the nu-clear envelope.
The nucleus contains the genetic material surrounded by the nuclear envelope. Controlling basic life functions, it is the most important component of the cell. DNA, which is the genetic material, codes the genetic information that determines our traits.
Cell membrane
The cell membrane separates the cell from the environment, maintaining a controlled connection with it. Cells take up and release various substances through the cell membrane. Chemical regulatory substances e.g. hormones that modulate cell functions, can bind to the surface of the membrane.
Cytoplasm
The inside of the cell is filled with a gelatinous substance called the cytoplasm, which is mostly composed of water. Cell organelles float around in it. Most cell organelles are wrapped in their own thin membranes and perform various functions. Examples include the mitochondria, which are the powerhouses of cells. There are large numbers of mitochondria in cells that carry out processes that require a lot of energy (e.g. cardiac and skeletal muscle cells).
