Carbohydrates: Monosaccharides, Disaccharides, Polysaccharides

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Definition of Carbohydrates

Carbohydrates are carbon, hydrogen, as well as oxygen-containing compounds.
Hydrogen atoms have twice the number of carbon or oxygen atoms.
C_x(H₂O)_y is a carbohydrate’s general formula.
They are energy sources (e.g. glucose), energy stores (e.g. starch as well as glycogen), as well as as structural elements (e.g. cellulose inside plants as well as chitins inside insects).

Polymers are the most common type of carbohydrate.
Polymers are lengthy chains of monomers that make up huge, complex compounds.
Monomers are molecular units that are tiny as well as simple.
Monosaccharides, disaccharides, as well as polysaccharides are the three types of carbohydrates available.

Monosaccharides are simple sugars that include one atom of oxygen plus two atoms of hydrogen for each atom of carbon.
Their general formula is (CH₂O)_n.
Monosaccharides help to lower blood sugar levels.
Benedict’s test is a procedure for lowering blood sugar levels.
Sweet-flavored sugars that are soluble in water but not soluble in non-polar solvents.
These could be seen in straight, ring, or cyclic chains.
Based on the number of carbon atoms within every molecule, these are classified as trioses (3C), tetroses (4C), pentoses (5C), hexoses (6C), heptoses (7), and so on.
The names of all sugars end in –ose.
Examples include Glyceraldehyde (triose), Erythrose (tetrose), Ribose (pentose), Glucose (hexose), Fructose (hexose), Galactose (hexose), Sedoheptulose (heptose), and others.
They provide energy to the body during respiration.
They are necessary for the formation of large molecules.

Disaccharides are formed by the condensation process of two monosaccharides.

The condensation reaction includes the production of a new chemical bond among two molecules, that results in the discharge of a water molecule.
A glycosidic bond is formed among two monosaccharides. Once carbon 1 on one monosaccharide connects carbon 4 on another monosaccharide, a 1,4-glycosidic bond is formed.

Maltose is composed of two -glucose molecules linked together by a glycosidic bond.
Sucrose is made whenever a glucose molecule as well as a fructose molecule combine in a condensation event.
Lactose is composed of a glucose molecule as well as a galactose molecule.
Sucrose is a non-reducing sugar.
The hydrolysis reaction breaks disaccharides into two monosaccharides by dissolving the glycosidic bond with the addition of water molecules. Water’s hydroxyl group (-OH) and hydrogen (-H) contribute in the breakdown of the glycosidic bond.
Sucrose is a transport sugar, whereas Lactose is a sugar present in milk, that is an essential nutrient of young mammals.

Polysaccharides are polymers generated by condensation processes which connect several monosaccharide molecules (more than two).
Oligosaccharides are molecules which contain 3-10 sugar units, while true polysaccharides contain 11 or more monosaccharides.
Polysaccharides do not have a sweet flavour.
The bulk of polysaccharides don’t dissolve in water because of their massive molecules.
Homopolysaccharides (Starch) are polysaccharides created entirely of one kind of monomer, whereas heteropolysaccharides are polysaccharides composed of than one monomer (Hyaluronic acid).

Long chains of -glucose make up starch (Amylose as well as Amylopectin). Glycogen is composed of α-glucose molecules connected by glycosidic linkages. Many β-glucose molecules are connected by glycosidic linkages between carbon 1 as well as carbon 4 in cellulose.
Starch is the main energy storage material in plants. Glycogen is the most common form of energy storage in mammals. Plant cell walls are primarily made up of cellulose.
An Iodine test is used to detect starch.

Carbohydrates Citations

2015. A-Level Biology Exam Board: AQA. Complete Revision and Practice. Original material by Richard Parsons.
Glenn Toole and Susan Toole. 2015. AQA Biology for A-Level. 2nd Edition. Oxford University Press.
Mary Jones, Richard Fosbery, Jennifer Gregory and Dennis Taylor. 2014. Cambridge International AS and A Level Biology Coursebook. 4th Edition. Cambridge University Press.
Mary Jones. 2010. Cambridge International A/AS-Level Biology Revision Guide. Hodder Education.
Sue Hocking, Frank Sochacki and Mark Winterbottom. 2015. OCR AS/A level Biology A. 2nd Edition. Pearson Education Limited

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