Name: Important Sources of Vitamins
Uploaded: 2019-07-19
Duration: 2 min 57 s
Description: Vitamins are essential for several biochemical reactions and the development of the body. This video describes their sources, types based on their solubility...

Question

Name the monosaccharide units present in sucrose and lactose.

Accepted Answer

Sucrose- It is the common disaccharide found in sugar cane and sugar beet. The sugar obtained from sugar beet is called beet sugar. Sucrose is the carbohydrates that on hydrolysis give two same or different monosaccharides $D - (+) - glucose and D - (-) - fructose$ , which are linked by each other by glycosidic linkage in the condensation reaction. Its general formula is $C_{12} H_{22} O_{11}$ . The following chemical reaction can be seen showing monosaccharide units found in fructose on hydrolysis-

$\underset{Sucrose}{C_{12} H_{22} O_{11}} + H_{2} O \overset{HCl / Invertase}{\to} \underset{D - (+) - glucose}{C_{6} H_{12} O_{6}} + \underset{D - (-) - fructose}{C_{6} H_{12} O_{6}}$

Fig- Monosaccharide units present in sucrose

Lactose- The disaccharide present in milk is lactose also known as milk sugar. It is a reducing sugar. Lactose on hydrolysis gives an equimolar mixture of $β - D -$ glucose and $β - D -$ galactose. Therefore, lactose is a disaccharide of glucose and galactose. It forms a glycosidic linkage between $C_{1}$ of galactose and $C_{4}$ of the glucose unit.

Fig- Monosaccharide units present in lactose

Name the monosaccharide units present in sucrose and lactose.

Important Questions on Biomolecules

Learn and Prepare for any exam you want !