Cellulose (C6H10O5)


By Tiffany Petrisko and Nikki Randall
cellulose.gif



Cellulose Structure


The polymer cellulose is made up of a long chain of the monomer glucose. The length of the chain can vary from a few 100 sugar units to over 6 000 sugar units. Scientists estimate that over 1 trillion tons of cellulose is synthesized by plants alone each year—this makes it one of the most common natural occurring polymers.

cellulose_diagram.gif
This is a 3D diagram of cellulose with its Beta-linkage

Dehydration Synthesis (Condensation)


Cellulose is a polysaccharide: a polymer of carbohydrates that is formed as many monosaccharide’s (in this case glucose) joined together by dehydration synthesis. Cellulose always forms in Beta- Linkage. Dehydration synthesis, also known as Condensation, is when a water molecule is removed “between” two monomers so that they may bond to one another. Cross-Linkage does not occur naturally in Cellulose. When cellulosed is used in manufacturing, cross-linkage often does occur then. Cross-linkage strengthens the bonds even more and makes it harder to break.

For a video of how dehyradtion synthesis works, check out this really helpful video!
http://www.coolschool.ca/lor/BI12/unit2/U02L05/DeSyn-maltosemovie.htm</span>




Nature's Gift


Cellulose occurs naturally and is thus found in nature. One of the most common (and certainly important) natural uses of cellulose is its presence in the cell walls of all plants. The cellulose is what gives the plants the stability to stand up and grow. Cellulose also occurs naturally in trees—it is the cellulose in the trees that also gives them their strength. Cellulose also occurs naturally in cotton (it makes up a very high percentage of cotton, estimated around 90%). Cellulose is also used by manufacturers to help build their products. It is commonly used in the textile industry to produce paper and cardboard. Cellulose is also used as an anticake agent, emulsifier, stabilizer, dispersing agent, a thickener, and gelling agent. There has also been a lot of studies done to understand cellulose to help aid the killing of pests (using it for pesticides).

Cellulose is also being considered as a biofuel. Cellulosic ethanol is a type of biofuel that is produced from lignocelluloses. Since cellulose is so abundant, it makes a great option for fuel; however, the question is, can we (mass) produce it. If you would like more information about cellulose as a biofuel, check out US New's opinion with the following link
http://www.usnews.com/articles/business/your-money/2008/01/11/cellulosic-ethanol.html<span. And for even more information on how understanding the digestion of cellulose is helping with pesticides, cellulosic ethanol, and more, check out some of the break through findings at the University of Florida's website at [[http://news.ufl.edu/2007/02/27/termite-gut/%3C/span%3E%3Cspan|http://news.ufl.edu/2007/02/27/termite-gut/<span]]


Physical Characteristics


Physically, the polymer cellulose is an insoluble straight-chained polymer. It is tasteless and odorless. The polymer is also chiral (there is no symmetrical plane in the polymer). Cellulose is also insoluble. Cellulose's other properties depend on the length of its chain. (And also, since cellulose occurs naturally it is of course, biodegradable).

Chemical Characteristics


Cellulose is very stable-- and that is a good thing! Without it, we would not have all the plants and trees that we do!

Many animals lack the ability to digest cellulose -- even many herbivores ("plant eaters"). Cows, koalas, and horses do digest cellulose, but they have special enzymes that digests the cellulose for them. Termites also contain special enzymes that can digest the cellulose for them. The termite, for example, contains protists (single celled organisms) called mastigophrans, in their digestive system that carry out the digestion of cellulose so their bodies may use it for energy. The termite provides a home for the protist while in return the cellulose is digested.
Humans lack the enzymes necessary to digest cellulose. Thankfully, humans do not eat food that is pure cellulose. Humans get a very low intake of cellulose from fruits and vegetables -- ever heard of dietary fiber? Cellulose is part of what makes up dietary fiber.

Another example of animals not being able to digest cellulose occurs in many insects. As of 1991, there were 4 ways in which it was believed that insects could digest cellulose.


  1. The first is by "protozoan symbionts residing in the hindgut (Bernays, 106)inside This coincides with what was said about the termites-- protozoan live inside the gut of the insect and digest the cellulose for it.
  2. The second way is the “capacity of bacteria residing in the hindgut” (Bernays, 106). This is the same idea as above, but with bacteria instead of protozoa.
  3. The third way is by the “reliance upon fungal celluloses, originating in the food, that remain active in the gut following digestion” (Bernays, 106). In simpler terms, this means that the insect eats a food that has fungi (most fungi are able to digest cellulose) and that fungi will continue to be able to digest the cellulose while in the gut of the insect.
  4. The final way is much debated in the scientific community “secretion by the insect of a complete cellulose system” (Bernays, 106). The quote means that the insect already contains all of the enzymes necessary for cellulose digestion, and as you have seen in the above, only fungi and protists have been able to digest cellulose.

As you can tell, it is not often that an animal can digest cellulose (especially without the aid of protists or fungi!)

cellulose-fibers.jpg
This picture is of the cellulose, and its fibers, in the cell wall of a plant.







Works Cited


American Fiber Manufacturers Association . Cellulose. 2008. 14 May 2008 <http://www.fibersource.com/f-tutor/cellulose.htm>.
Bernays, E.A, Martin, Michael M., Jones, C.G. “The Evolution of Cellulose Digestion in Insects [and Discussion]. Philosophical Transactions: Biological Services.333-1267 (Aug. 29, 1991): 281-288.
Chaplin, Martin. "Cellulose" Water Structure and Science. 12 May 2008. 13 May 1008 <[[http://trj.sagepub.com/cgi/content/abstract/31/2/160%3C/span%3E%3Cspan|http://trj.sagepub.com/cgi/content/abstract/31/2/160<span]]
Clark, Jim. "Stereoisomerism-potical isomerism" Chemguide. 2004. 13 May 2008
<http://www.chemguide.co.uk/basicorg/isomerism/optical.html#top>.
Decelles, Paul. Carbohydrates. 15 July 1999. 15 May 2008 <
http://staff.jccc.net/PDECELL/biochemistry/carbohyd.html>.
Garden, John L. Richard Steele. "Some Theoretical Considerations of Cellulose Cross-Linking". SAGE Journals Online. Sage Publications. 16 May 2008 <[[http://trj.sagepub.com/cgi/content/abstract/31/2/160%3C/span%3E%3Cspan|http://trj.sagepub.com/cgi/content/abstract/31/2/160<span]]
Net Industries . Cellulose Digestion . 2008. 14 May 2008 <
http://science.jrank.org/pages/1335/Cellulose-Cellulose-digestion.html>.

Nordie, Tom. UF research: Termite digestion findings could lead to new strategies for ethanol production, pest control. 27 February 2007. 15 May 2008 <http://news.ufl.edu/2007/02/27/termite-gut/>.
"Polymers Up Close and Personal" The Macrogelleria. 14 May 2008 <[[http://pslc.ws/macrog/level2.htm%3C/span%3E%3Cspan|http://pslc.ws/macrog/level2.htm<span]]
Renewable Fuels Association . Cellulosic Ethanol. 2005. 15 May 2008 <
http://www.ethanolrfa.org/resource/cellulosic/>.
Reuch, William. "Polymers" Virtual Textbook of Organic Chemistry.16 July 2007. 14 May 2008 <[[http://www.cem.msu.edu/~reusch/VirtualText/polymers.htm%3C/span%3E%3Cspan|http://www.cem.msu.edu/~reusch/VirtualText/polymers.htm<span]]
Senese, Fred. What is Cellulose. 2005. 13 May 2008 <[[http://antoine.frostburg.edu/chem/senese/101/consumer/faq/what-is-cellulose.shtml%3E%3C/span%3E%3C/span%3E.|http://antoine.frostburg.edu/chem/senese/101/consumer/faq/what-is-cellulose.shtml>.]]