General Characteristics of Living Beings

How can you distinguish a living being from an inanimate being?

Living things share some characteristics in common. See below.

Cell Organization

With the exception of viruses, all living things are cells. Cell is the smallest part with definite form that constitutes a living being with self-duplicating ability (can divide itself). They are the structural and functional units of living organisms. They can be compared to the bricks of a house. Cells are usually so small that they can only be seen by microscope. Within them occur numerous processes that are fundamental to maintaining life.

Humans have about 100 trillion cells; a typical cell size is 10 µm (1 µm = 0.000001m); A typical cell mass is 1 nanogram (1ng = 0.000000001g). The largest known cell is the ostrich egg yolk.

A medium-sized ostrich egg is 15 cm long, 12 cm wide, and weighs 1.4 kg. They are the largest eggs of a living species (and the largest single cells), although they are actually the smallest relative to bird size.

Chemical composition

It is represented by:

  • Inorganic Substances: water and mineral salts.
  • Organic substances (carbon as main element): carbohydrates, lipids, proteins, nucleic acids and vitamins.

The approximate chemical composition of living matter is 75 to 85% water; 1% mineral salts; 1% carbohydrate; 2 to 3% lipids; 10 to 15% protein and 1% nucleic acid.

Cell Number

All living things are made up of cells, but the number of cells varies from one being to another.

There are beings unicellular, the word unicellular has its origin in Latin uni, which means "one, only". These are bacteria, cyanobacteria, protozoa, unicellular algae and yeast.

Bacterium Escherichia coli, electron microscope view, be unicellular.

Protozoan cell forms, beings unicellular.

The beings multicellular are formed by several cells, the word multicellular originates from the Latin pluriwhich means "more, bigger".

The onion is a vegetable, therefore a multicellular being.

Cut the onion tissue, showing the various cells placed next to each other.