How many molecules of water are released during the polymerization of a 20 monomer-long cellulose molecule?
A 20
B 40
C 10
D 19
The correct answer and explanation is:
The correct answer is D) 19.
Cellulose is a polymer made up of glucose monomers linked by β-1,4-glycosidic bonds. When cellulose is synthesized, each time a new monomer is added, a molecule of water is released. This occurs through a condensation reaction where a hydroxyl group (–OH) from one glucose molecule reacts with a hydrogen atom (–H) from the other monomer, forming a glycosidic bond and releasing one molecule of water.
To understand how many water molecules are released in the polymerization of a cellulose molecule that is 20 monomers long, let’s break it down:
- For the first monomer, there is no water released, as it is the starting point of the chain.
- For each additional monomer added, a water molecule is released.
- If the molecule has 20 monomers, then 19 bonds are formed between the monomers (one less than the total number of monomers because the first monomer does not require a bond).
Thus, 19 water molecules are released as 19 glycosidic bonds are formed between the 20 glucose units.
This concept of water release due to condensation reactions is common in the formation of polysaccharides like cellulose and starch, where each addition of a monomer to the polymer chain involves the release of one water molecule. Therefore, for a 20 monomer-long cellulose molecule, 19 water molecules are released during its polymerization.