Students can go through TS Inter 2nd Year Chemistry Notes 9th Lesson Biomolecules will help students in revising the entire concepts quickly.
TS Inter 2nd Year Chemistry Notes 9th Lesson Biomolecules
→ Carbohydrates are optically active polyhydroxy aldehydes or ketones or molecules which provide such units on hydrolysis.
→ Most of the carbohydrates have the general formula Cx(H2O)y.
→ Carbohydrates which are sweet to taste are called sugars.
→ Carbohydrates are also called saccharides.
→ On the basis of hydrolysis, carbohydrates are classified into monosaccharides, oligosaccharides and polysaccharides.
→ Carbohydrates which cannot be hydrolysed into simpler units are called monosaccharides. Ex: Glucose, fructose.
→ Carbohydrates which yield two to ten mono-saccharide units on hydrolysis are called oligosaccharides.
→ Sucrose (Cane sugar) is a disaccharide. It gives one molecule of glucose and one molecule of fructose on hydrolysis.
→ Maltose on hydrolysis gives two molecules of glucose only.
→ Carbohydrates which yield a large number of monosaccharide units on hydrolysis are called polysaccharides. Ex: Starch, cellulose.
→ Glucose is an aldohexose whereas fructose is a ketohexose. Glucose is also known as dextrose.
→ In the laboratory glucose is prepared by boiling sucrose with dil. HCl or H2SO4 in alcoholic solution.
→ Starch on boiling with dilute H2SO4 at 120°C and under pressure, undergoes hydrolysis and gives Glucose.
→ On prolonged heating with HI glucose forms n – Hexane.
→ Glucose reacts with hydroxylamine to give an oxime.
→ Glucose is oxidised by bromine water to give gluconic acid.
→ Acetylation of glucose with acetic anhydride gives glucose pentaacetate.
→ Glucose and gluconic acid on oxidation with nitric acid give saccharic acid.
→ The letter ‘D’ or ‘L’ before the name of any compound indicates relative configuration of a particular stereo isomer.
→ Glucose is correctly named as D – (+) – glucose. Here (+) represents dextrorotatory nature.
→ The open chain structure of glucose explained most of its properties but it could not explain some facts regarding glucose. Glucose does not give Schiff’s test and it does not form bisulphite addition product with NaHSO3.
→ A pyranose ring structure was proposed for glucose.
→ Glucose exists in two cyclic hemiacetal forms which differ in their configuration at C1, called the anomeric carbon. These isomers
i. e., α – form and β – form are called anomers.
→ Glucose is dextrorotatory whereas fructose is laevorotatory.
→ Fructose is given a furanose ring structure.
→ The two monosaccharide units in a disaccharide are joined by an oxide linkage formed by the loss of a water molecule. Such a linkage between two monosaccharide units through oxygen atom is called glycosidic linkage.
→ Sucrose on hydrolysis gives equimolar mixture of glucose and fructose. The product is called invert sugar.
→ Lactose on hydrolysis gives galactose and glucose.
→ Starch is a polymer of a – glucose and consists of two components – Amylose and Amylopectin.
→ The carbohydrates are stored in animal body as glycogen.
→ Proteins are the polymers of about 20 different α – amino acids which are linked by peptide bonds.
→ Amino acids which can be synthesised in the body are called non – essential amino acids. Ex: Glycine, Alanine.
→ Amino acids which cannot be synthesised in the body and must be obtained through diet are known as essential amino acids. Ex: Valine, Lysine.
→ When a protein in its native form, is subjected to physical change like change of temperature or chemical change like change in pH, it loses its biological activity. This is called denaturation of protein.
→ Enzymes are biocatalysts which speed up the reactions in biosystems.
→ Vitamins are organic molecules which are required in small quantities in our diet and their deficiency causes specific diseases.
→ Nucleic acids are five membered ring sugars linked by phosphate groups.
→ Nucleic acids are mainly of two types.
- Deoxyribonucleic acid (DNA) and
- Ribo-nucleic acid (RNA). Nucleic acids are also called polynucleotides.
→ Hormones are molecules that act as intercellular messengers.
→ Hormones have several functions in the body and help to maintain the balance of biological activities in the body.