Animal Cell Structure
This page includes the basic structure of a general human cell (i.e. an animal cell rather than a plant cell) and some of the organelles within it.
Histology is the microscopic study of the structure of biological tissues using special staining techniques combined with light and electron microscopy. The detail of even the general cell structure summarised below cannot be observed without the use of these modern techniques.
The structure of cells varies according to the type and purpose of the cell (for example, which functions it is performing and in which part of the body). All plant and animal cells contain organelles which are structures within the cell that are specialised for particular functions.
Are there any cells that do not contain organelles ?
Yes: Prokaryotic cells, e.g. bacteria cells, do not contain "true" membrane-bound organelles - not even a nucleus. Conversely, plant cells and animal cells are examples of eukaryotic cells which contain various types and quantities of membrane-bound organelles, depending on the specific type of cell and its functions within the organism of which it is a part.
The following very simple diagram illustrates a single animal cell with simple representations of key organelles:
Click on the names of the cell components and organelles listed below for more information:
It is also important to know something about each of these organelles:
Other components of a typical cell not shown on the above simple diagram include: cilia (sing. cilium), cytosol - a component of cytoplasma, glycogen granules, intermediate filaments, microtubules, microfilaments, pericentriolar areas (around the centrioles), peroxisomes and secretory vesicles.
A simple representation of the structure of animal cell membranes is shown below.
This is illustrates a cross-section of the phospholipid bilayer that forms the membrane around the outside of all animal (including human) cells.
This plasma membrane consists mainly of phospholipids and proteins, most of the membrane proteins being glycoproteins. The two components of the phospholipids are the heads (represented by black circles), and the fatty acid tails (that extend into the phospholipid bilayer).
Other molecules present in the plasma membrane generally include cholesterol (as illustrated) and glycolipids.
Note that this membrane is non-rigid; if the cell had a cell-wall then it would be rigid ... and a plant cell.
Integral Proteins extend through the bilipid layer and among the fatty acid tails of the phospholipids - though not necessarily all the way through the plasma membrane.
Peripheral Proteins are loosely attached to (either the interior or exterior) surface of the plasma membrane.