cells are the main biological unit. The volume varies between 1 to 1000 mircrometri.
The relationship between surface and volume: volume determines the amount of time for reactions, the surface the amount of substances that can absorb or expel.
cells are surrounded by a
cytoplasmic membrane (phospholipid bilayer) and are intended to maintain internal continuous, selectively permeable barrier, communication with neighboring cells and receive signals. cell bodies are divided between
Archaea, Bacteria
(prokaryotic cells) and eukaryotes (cells ecucariotiche).
Prokaryotic cells Prokaryotic cells are smaller than the eukaryotic, but may use many more types of energy and survive the most extreme environments. They are structurally simple but functionally complex, thousands of chemical reactions. are composed of membrane and cytoplasmic
nucleoid that contains the DNA. The rest is
cytoplasm containing cytosol (H20, ions, proteins) and ribosome
(sets of RNA).
Some prokaryotes have developed other properties in
Cell wall outside, may contain peptidoglycan phospholipid and an additional barrier.
Some have a capsule that can withstand attacks other bodies.
Flagella and pili
The flagella, flagellin
contain protein, are grafted onto the membrane and are driven by a motor protein, they serve the movement. Pili are smaller than flagella and are used for the exchange of material between prokaryotes.
Cytoskeleton
Some bacteria contain a stick-helical structure that gives the filamentous form.
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