The Perfect Mechanism
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The Perfect Mechanism
8
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The Secret of Cells
The human body is made up of about 4 × 1013 cells, which
vary greatly in both size and shape. The largest cell is the egg, which can reach up to 100 microns in diameter. The smallest ones are the platelets, which are blood components with
a size of a mere 2 microns.
Their life span varies too: while certain white blood cells survive only for a few hours, most neurons are formed
before birth and survive for our entire lifetime. While the shape of cells varies, their structure is nearly the same.
Animal or plant cell?
Endoplasmic reticulum
A complex, interconnected network
of membrane vesicles inside the cell.
It plays an important role in protein synthesis, protein processing, lipid synthesis and the breaking down of certain substances.
The cell is the basic structural and func-
tional unit of all living organisms. Plants and animals are all built up of cells. Our bodies are also made up of animal cells.
There are significant differences between the cells of plants and animals, and they can be easily distinguished from one another. If we look closely, we can see
the green chloroplasts, the cell wall and vacuoles in plant cells, which are not present in animal cells.
nuclear membrane
chloroplast
cell wall
Nucleus
The control centre of the cell, it controls cellular metabolic processes. It consists of three components: the cell membrane, the nucleolus and chromatin. The nucleus contains the genetic information of the cell.
vacuole
Cell membrane
A thin layer that separates the cell from the outside environment. It controls
the transport of substances in and
out of the cell, thereby maintaining
the internal balance of the cell.
Cytoplasm
A transparent, gel-like
substance; the site of
some of the cell’s
metabolic processes.
Mitochondrion
It provides the energy
necessary for the cell for its processes. It releases carbon dioxide as a by-product.
The Golgi apparatus
It packages substances
produced by the cell
before sending them
to their final destination.
Protein filaments
These protein filaments are found in the cytoplasm. Together with the microtubules, they form the cytoskeleton. The cytoskeleton plays an important role in the movement
of the constituents of the cytoplasm and provides the cell with a structural framework.
chromatin
nucleolus
