Sugar molecule that strengthens wood: Cellulose

How does cellulose, which is in fact a sugar molecule, strengthen wood?

Why is this molecule important for termites?

Despite the fact that koalas cannot digest cellulose, the primary material of eucalyptus, how is this molecule utilized in the koala bear’s system?

“Sugar” generally reminds people of something that they add to their tea or something sweet they eat. However, the sugar we use in our daily lives is a derivate of sugar molecule which is found in a variety of forms in nature and used in a wide range of areas. Sugar molecule is one of the members of the large family, called “carbohydrates” in chemistry. Carbohydrates are of great importance for living organisms. Glucose and glycogen, two of the most important energy sources of living beings; starch that is created through photosynthesis in plants, and cellulose, the most important constituent of the cell wall of plants are all carbohydrates, that is, sugar molecules.

It is a little known fact that cellulose, a molecule that constitutes 50% of wood texture and 90 % of cotton, is in fact a sugar molecule. However, the incredible features of cellulose are not limited to these.
 

Vital Qualities of Cellulose

Cellulose is a hard and water insoluble material. It is generally found in the protective walls of plants, tree branches, tree bodies and wooden textures of trees.

 Cellulose is the primary component of the plant cell wall. Some plants,  especially aquatic ones, are in a dangerous environment. These plants sometimes have to live in salt water, and sometimes in environments where the salt concentration is reduced due to the melting of snow or flux of lakes. They need a strong cell wall to protect themselves from such a harsh environment. That is why Allah has created tightly packed cellulose groups in plant cells. (Prof. Dr. Engin M. Gözükara, Biyokimya [Biochemistry], Vol. 1, 3. Edition, 1997, Nobel Tıp Kitabevleri, p. 232)

Although cellulose is a sugar molecule, a polysaccharide, like starch, it is not possible for humans to digest it as the glucose units in cellulose are bound  together  with glycosidic bonds. There is not an enzyme that can digest this bond in the alimentary canal of mammals. That’s why cellulose is not a food source for us. It can only be digested by ruminants, since there are some microorganisms in the alimentary canals of these animals. These microorganisms can easily digest the cellulose in the body with their enzymes and transfer them into food and energy for the animal.
 

How Can A Sugar Molecule Strengthen Wood?

The hard and tough structure of the tree is formed thanks to cellulose fibers. What makes wood advantageous in buildings is this feature of cellulose. Cellulose, which is defined as a “stretchable and novel” material, is used in the building of structures and bridges that can stand still for ages, and the manufacture of furniture and many devices.

Wood consists of  long, hollow cells that are laid end-to end. It is covered by spiral cellulose fibers.  Moreover, these cells swim in “lignin”, which is made of complex polymer structured gum.  These spirally covered layers, make up 80 % of the total thickness of the cell wall and the part that carries the main load. When a wood cell is damaged, it absorbs the energy of the impact by splitting itself from the cells surrounding it. Although collapses create a deep crack along the fibers, the wood remains complete. Thus, the wood has the power to carry the entire load although it is broken.

Wood is an important material from the point of view that it absorbs the energies of low-speed impacts and reduces the damage impacts may cause. In the manufacture of “Mosquito” planes used in World War II, the most damage tolerant planes were built by sandwiching wood in plywood layers. The hardness and toughness of wood make it a reliable material. When the wood is breaking, cracking happens in such a slow way that one can see it before it is broken; and this feature allows us time to take necessary measures. (Julian Vincent, “Tricks of Nature”, New Scientist, 17 August 1996, vol. 151, no. 2043, p. 39)

A material, made by taking the structure of wood as the model, is 50 times more durable than today’s synthetic materials. This special structure of wood is imitated in materials developed to provide special security against destructive, high speed bullets and bombs. However, it is impossible for scientists to imitate a piece of wood, with all its qualities. Every detail in the creation of wood – the refinement of its layers, the number of veins, its arrangement and constituents - are all specially created to provide this strength.
 

Everything in the heavens and the earth glorifies Allah. He is the Almighty, the All-Wise. (Surat al-Hadid, 1)