what are the smallest cell and the biggest cell in the nature?
451866
It depends whether you are talking about organisms that are single cells, or cells that exist in eukaryotic tissues.\n\nThe problem with finding the smallest cells is that they will undoubtedly turn out to be the smallest bacteria... these organisms are likely to exist only in places that are very difficult to reach, because extremely small size is in fact an adaptation to a (typically harsh) environment: reduction in size maximises surface area in proportion to volume.  When life gets very tough, having a maximal surface area is important, because in general, important life processes occur through cell walls and surface membranes.\n\nSome hyperthermophilic archaea (archae-bacteria that colonise hot volcanic and deep subterranean environments) are rod-shaped organisms 0.17 microns in diameter (genus Thermofilium), disk-shaped organisms 0.2-0.3 microns in diameter, 0.08-0.1 thick (genera Thermodiscus & Pyrodictium).\n\nCells in the human body are typically 5-20 microns thick.  I think Bacteria_Boy could be right about the nerve cell.\n\nIndividuals of the genus Acetabularia, a protist (single-celled) marine green alga, are composed of clearly differentiated parts (eg: foot, stalk, head), but grow up to about 5 cm in height.  These are the largest single-celled organisms that I know of.
547120
A Bacterium.\n\nCells that lack a membrane-bound nucleus are called prokaryotes (from the Greek meaning before nuclei). These cells have few internal structures that are distinguishable under a microscope. Cells in the monera kingdom such as bacteria and cyanobacteria (also known as blue-green algae) are prokaryotes.
947862
With the most powerful electron micropscopes scientists can acheive a magnification of 2 million times which will still not allow us to see anything as tiny as proteins as molecules.  The smallest biological material that I can think of is nanobacteria that are 300 *10^-9 m in size but the existance of nanobacteria is still disputed.  The following gallery gives a good idea of the range that normal EM's work in.
523135
Human beings have an estimated 100 trillion or 10^14 cells; a typical cell size is 10 µm, a typical cell mass 1 nanogram.\nIf we take the latter number, then a adult of 80 kg has 8x10^13 cells, a teenager of 40 kg half as much.
539401
phytoplankton, algae, u name it, everything smaller than it is!
1038177
prokaryotic cells are the ONLY cells on that list that have no nucleus or organelles....\n\n...someone hasn't been paying very much attention in class....
89687
Both are eukaryotic (containing a "true nucleus").  \n\nAnimal Cells lack a cell wall and adjacent cells are connected by junctions (adhesive, gap or tight).  Animal cells contain centrioles (help create microtubules used in mitosis and meiosis) and lysosomes (organelles used to digest wastes and old organelles). During telophase and cytokinesis the cells separate via a cleavage furrow.\n\nPlant Cells contain a cell wall (think of the cell wall as the "skeleton" composed mainly of cellulose) and rely on turgor pressure to keep them upright.  Adjacent cells are connected by channels called plasmodesmata.  You will not find centrioles or lysosomes in a plant cell, but you will find a really cool organelle called a large centrol vacuole.  This organelle is where the water is stored in a cell and it helps maintain the turgor pressure described above.  It also acts as a lysosome, storing chemicals and waste products.  The Central vacuole can also store the pigments you see in flowers as well as poisons used to deter predators.  And of course, in a plant cell you will find the plasts as mentioned by someone earlier.. including the famous chloroplasts (the site for photosynthesis) as well as the chromoplasts (contain pigments) and amyloplasts (specialized for starch storage). During telophase and cytokinesis, the cells are separated by a structure called a cell plate.   \n\nUmmm, that's all I can come up with right now!
282546
well i know that a human red blood cell is 10 µm (10 - 30 µm), I'm not sure what a virus is but i think it is significantly smaller.
517457
Cells are not all of the same size, but average size is close to 15 micrometers.
455022
cells dont have cells but they they have organelles which are sort of like cells, which includes mitochondria, ribosomes, golgi apparatus, etc. that have various functions such as converting sugar to energy, synthesizing proteins, etc. they're sort of like minature organs if the cell was your body (hence the name organelles
891803
A cell would have the most entropy since it has a lot of different things inside of it that can be arranged in different ways.
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With the increase in cell size the ratio between surface area and volume decreases. A large cell will therefore  have less surface area compared to the volume to  cope with the demands of the cell as far as the exchange of materials between the extracellular environment and the cytoplasm is concerned.On the other hand a smaller cell will have large surface area to adequately meet the demands of the volume of the  cytoplasm.The cell volume depends upon r to the power 3 and the cell surface depends upon r(radius) to the power 2. This becomes the limiting factor for the growth of the cell.
819308
Cells. Cells are the basic unit of life. They make up every single living thing in the universe. Humans, plants, animal, bacteria, fungi, and every other living thing in the universe.
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sex cells. they only have half the nomal number of chromosomes.
283526
Cell bio would encompass all things on a cellular level.\nUsually organisms with a "life of their own".\nMolecular bio goes further into the atomic level.\nEg: a molecule of water (H2O) consists of 3 atoms. take a H away and you have Hydrogen peroxide(HO). A cell is usually made up of many different molecules when added together, make an organism like a liver cell, cancer cell, stem cell,etc...
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A plant cell has a cell wall.\n\nhttp://www.bbc.co.uk/schools/ks3bitesize/science/biology/lifecells2_3.shtml
899833
GB(GigaByte) is the biggest, MB (MegaByte) is in the middle, and KB (KiloByte) is the smallest.