Carbohydrates
The word 'Carbohydrate' is made up of Carbon and hydrate - Water/H2O.
Carbohydrates are divided into three main groups:
Monosaccharide, Disaccharide, Polysaccharide
Carbohydrates are divided into three main groups:
Monosaccharide, Disaccharide, Polysaccharide
Monosaccharide
Has the molecular formula of Cx(H2O)y, with 'x' being the number of Carbon atoms in the molecule and 'y' for the water molecule.
Monosaccharide means a single (one) sugar molecule. In everyday lives, Monosaccharides is used as a source of respiration energy for different kinds of organisms, but most importantly, it acts as building blocks for larger molecules.
Common examples of Monosaccharides are:
Monosaccharide means a single (one) sugar molecule. In everyday lives, Monosaccharides is used as a source of respiration energy for different kinds of organisms, but most importantly, it acts as building blocks for larger molecules.
Common examples of Monosaccharides are:
- Triose (3 Carbons)
- Pentose (5 Carbons) (Ribose & Deoxyribose)
- Hexose (6 Carbons), including Glucose, Fructose, and Galactose
Disaccharide (and glycosidic bond)
Common examples of disaccharides are:
There are 2 forms of glucose, a-glucose and b-glucose as shown in Figure 1.1:
- Maltose (glucose + glucose)
- Sucrose (glucose + fructose)
- Lactose (glucose + galactose)
There are 2 forms of glucose, a-glucose and b-glucose as shown in Figure 1.1:
A disaccharide is formed by two monosaccharides joining together by glycosidic bonds.
These glycosidic bonds only forms when the two molecules goes through condensation, where the H2O is released and an oxygen atom then becomes the bridge between the two molecules. This is shown in Figure 1.2.
These glycosidic bonds only forms when the two molecules goes through condensation, where the H2O is released and an oxygen atom then becomes the bridge between the two molecules. This is shown in Figure 1.2.
Polysaccharide
A polymer which is made of lots of monosaccharides with glycosidic bonds forming in between each molecules. Mostimportant polysaccharides are monomers of glucose, and since glucose is used as energy for cells, it needs to be stored appropriately.
Glucose is stored by condensing them to a storage polysaccharide. It forms as starch in plants and glycogens in animals.
Starch is made of mixtures of amylose and amylopectin (Figure 2.1), and is very common in potatoes.
Amylose is made of 1,4 linked a-glucose, is long and unbranched. They are curved and coil up into helical structures.
Amylopectin is made of 1,4 linked a-glucose, is short and branched to the side by 1,6 links.
Glycogen is a stoage carbohyrate for animals. It is made of amylopectin, but is more branched than amylopectin.
Glucose is stored by condensing them to a storage polysaccharide. It forms as starch in plants and glycogens in animals.
Starch is made of mixtures of amylose and amylopectin (Figure 2.1), and is very common in potatoes.
Amylose is made of 1,4 linked a-glucose, is long and unbranched. They are curved and coil up into helical structures.
Amylopectin is made of 1,4 linked a-glucose, is short and branched to the side by 1,6 links.
Glycogen is a stoage carbohyrate for animals. It is made of amylopectin, but is more branched than amylopectin.
Cellulose is a strong molecule, and is similar to Amylopectin but is a polymer of b-glucose. One of the molecule needs to be turned upside down 180 degrees (Fig 2.2) in order for the condensation process to happen. This arrangement also forms hydrogen bonds.
The cellulose molecules will be "tightly cross-linked" to form bundles called as microfibrils. They will be held together in bundles by hydrogen bonding to something known as fibers.
Cellulose is a strong molecule, and is similar to Amylopectin but is a polymer of b-glucose. One of the molecule needs to be turned upside down 180 degrees (Fig 2.2) in order for the condensation process to happen. This arrangement also forms hydrogen bonds.
The cellulose molecules will be "tightly cross-linked" to form bundles called as microfibrils. They will be held together in bundles by hydrogen bonding to something known as fibers.
Tests
Testing the presence of Sugar: Benedict's Test
Reducing sugar intensity: green, yellow, orange, red-brown Procedure Add Benedict's reagant to the solution and heat it. If the results turn colour to one of the above, it contains reducing sugar. For non reducing sugar Heat the solution with hydrochloric acid, neutralise it by adding an alkali (Sodium Hydroxide). Add benedict's reagant and heat. Observe Testing the presence of Starch: Iodine solution Iodine solution fits in the hold of starch molecules. Procedure Drop Iodine solution to the substance. If starch is present, the colour should turn to blue-black. |