Difference Between Similar Terms and Objects. MLA 8 ,. Name required. Email required. Please note: comment moderation is enabled and may delay your comment. There is no need to resubmit your comment. Notify me of followup comments via e-mail. Written by : lancepenpal. User assumes all risk of use, damage, or injury. You agree that we have no liability for any damages. Cellulose is the most abundant natural biopolymer.
The cell wall of plants is mostly made of cellulose; this provides structural support to the cell. Wood and paper are mostly cellulosic in nature. Figure 7. Because of the way the glucose subunits are joined, every glucose monomer is flipped relative to the next one resulting in a linear, fibrous structure. As shown in Figure 7, every other glucose monomer in cellulose is flipped over, and the monomers are packed tightly as extended long chains. This gives cellulose its rigidity and high tensile strength—which is so important to plant cells.
In these animals, certain species of bacteria and protists reside in the rumen part of the digestive system of herbivores and secrete the enzyme cellulase.
The appendix of grazing animals also contains bacteria that digest cellulose, giving it an important role in the digestive systems of ruminants. Cellulases can break down cellulose into glucose monomers that can be used as an energy source by the animal. Termites are also able to break down cellulose because of the presence of other organisms in their bodies that secrete cellulases.
Figure 8. Insects have a hard outer exoskeleton made of chitin, a type of polysaccharide. Carbohydrates serve various functions in different animals. Arthropods insects, crustaceans, and others have an outer skeleton, called the exoskeleton, which protects their internal body parts as seen in the bee in Figure 8.
This exoskeleton is made of the biological macromolecule chitin, which is a polysaccharide-containing nitrogen. Chitin is also a major component of fungal cell walls; fungi are neither animals nor plants and form a kingdom of their own in the domain Eukarya. Carbohydrates are a group of macromolecules that are a vital energy source for the cell and provide structural support to plant cells, fungi, and all of the arthropods that include lobsters, crabs, shrimp, insects, and spiders. Carbohydrates are classified as monosaccharides, disaccharides, and polysaccharides depending on the number of monomers in the molecule.
Monosaccharides are linked by glycosidic bonds that are formed as a result of dehydration reactions, forming disaccharides and polysaccharides with the elimination of a water molecule for each bond formed.
Glucose, galactose, and fructose are common monosaccharides, whereas common disaccharides include lactose, maltose, and sucrose. Starch and glycogen, examples of polysaccharides, are the storage forms of glucose in plants and animals, respectively. The long polysaccharide chains may be branched or unbranched.
Cellulose is an example of an unbranched polysaccharide, whereas amylopectin, a constituent of starch, is a highly branched molecule. This forms a six-member ring structure. The ring is also called a hemiacetal ring, due to the presence of carbon that has both an ether oxygen and an alcohol group. Because of the free aldehyde group, glucose can be reduced. Thus, it is called a reducing sugar. Further, glucose is also known as dextrose because it rotates plane-polarized light to the right.
When there is sunlight, in plant chloroplasts, glucose is synthesized using water and carbon dioxide. This glucose is stored and used as a source of energy. Animals and human obtain glucose from plant sources.
The glucose level in human blood is regulated by the homeostasis mechanism. Insulin and glucagon hormones are involved in the mechanism. When there is high glucose level in the blood, it is called a diabetic condition. The measurement of blood sugar level measures the glucose level in blood. Therefore, glucose is called an aldohexose. Figure 1: The chair confirmation of D-Glucose. The above image shows the general structure of glucose. This image indicates that glucose has four chiral centers.
A chiral center is a carbon atom having four different groups attached to it. Therefore, glucose has stereoisomers. The naturally occurring glucose is known as D-Glucose. The isomer of D-Glucose is L-Glucose. But the L-Glucose does not occur naturally.
Glucose is water soluble and is colorless when dissolved in water. Glucose can occur as an open chain or as a cyclic structure. But the open chain is typically unstable and spontaneously converts into cyclic form.
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