PHYSICS-15-10- 11th (PQRS) SOLUTION

https://docs.google.com/document/d/1CGTrI2oXfER1yhnFFXC9_ys-_mivj2vA/edit?usp=sharing&ouid=109474854956598892099&rtpof=true&sd=true Biomolecules General introduction and importance of biomolecules. CARBOHYDRATES - Classification: aldoses and ketoses; monosaccharides (glucose and fructose), constituent monosaccharides of oligosacchorides (sucrose, lactose, maltose) and polysaccharides (starch, cellulose, glycogen). PROTEINS - Elementa ry Idea of ? - a mino a c ids, peptid e bond, polypeptides; Proteins: primary, secondary, tertiary and quaternary structure (qualitative idea only), denaturation of proteins, enzymes. VITAMINS - Classification and functions. NUCLEIC ACIDS - Chemical constitution of DNA and RNA. Biological functions of nucleic acids. All living organisms are made of one or more cells which are considered as the smallest units of life. Thus cell is a fundamental structural and functional unit of living organisms. All the carbon compounds associated with cells are classified as Carbohydrates Amino Acids and Proteins Nucleic Acids Lipids CARBOHYDRATES Carbohydrates are mainly compounds of carbon, hydrogen and oxygen. General formula initially considered was Cx(H2O)y e.g., glucose – C6H12O6, sucrose C12H22O11 etc. But many of the compounds behave as carbohydrates but do not follow the Cx(H2O)y formula. Thus carbohydrates are the class of compounds that include polyhydroxy aldehydes or polyhydroxy ketones. Carbohydrates are also known as saccharides. Classification The carbohydrates are classified into three major classes Monosaccharides Oligosaccharides Polysaccharides Monosaccharides Monosaccharides are simple sugars with single unit of polyhydroxy aldehyde or polyhydroxy ketones. General formula CnH2nOn (with some exceptions). C H A P T E R CHAPTER INCLUDES Carbohydrates Monosaccharides Disaccharides Oligosaccharides Polysaccharides Glucose Preparation and Properties Amino Acids Proteins Enzymes Nucleic Acids Vitamins Oligosaccharides Oligosaccharides are made up of 2-9 units of monosaccharides or simple sugars. Oligosaccharides with two, three, four monosaccharides respectively known as disaccharides, trisaccharides, tetrasaccharides. Sucrose is the example of this class C H O H O H+ C H O C H O 12 22 11 2 ⎯ ⎯→ 6 12 6 6 12 6 Polysaccharides (sucrose) (glucose) (fructose) Polysaccharides are made up of 'n' number of monosaccharide units (above 10 carbon atoms). Starch, cellulose, glycogen are the examples of this class. (C6H10O5 )n ⎯⎯nH2⎯O → nC6H12O6 starch H+ glucose Homopolysaccharides are made up of single type of monosaccharides. Heteropolysaccharide is made up of two or more different types of monosaccharides. Monosaccharide-Glucose Glucose is known as dextrose and also known as grape sugar. Preparation Acid hydrolysis of cane sugar in presence of alcohol gives glucose (along with fructose). C12H22O11 + H2O ⎯→ C6H12O6 + C6H12O6 sugar Chemical Properties Reaction with PCl5 : CHO glucose CHO fructose (CHOH)4 CH2OH + 5PCl5 (CHCl)4 CH2Cl + 5POCl3 + 5HCl Glucose Penta-chloroglucose Reaction with acetic anhydride : CHO (CHOH)4 CH2OH + (CH3CO)2O CHO (CHOCOCH3)4 CH2OOCCH3 Penta-acetate glucose Reduction : CHO (CHOH)4 + 2H CH2OH Na-Hg H2O CH2OH (CHOH)4 CH2OH Sorbitol Reaction with Fehling's solution : CHO (CHOH)4 CH2OH + 2CuO COOH (CHOH)4 CH2OH Gluconic acid + Cu2O red ppt. Reaction with Tollen's reagent : CHO (CHOH)4 CH2OH + Ag2O COOH (CHOH)4 CH2OH + 2Ag (mirror) Reaction with HNO3 : Gluconic acid CHO (CHOH)4 CH2OH + 3[O] HNO3 COOH (CHOH)4 COOH Saccharic acid (Glucaric acid) Reaction with phenylhydrazine : CHO CHOH (CHOH)3 CH2OH D-glucose + H2NNHC6H5 CH NNHC6H5 (Phenylyhydrazine) CHOH (CHOH)3 CH2OH D-glucose phenylhydrazone H2NNHC6H5 CH NNHC6H5 CH NNHC6H5 C NNHC6H5 H2NNHC6H5 C O (CHOH)3 CH2OH Lobry de Bruyn-van Ekenstein rearrangement reaction : Glucose on reaction with dilute NaOH undergoes a reversible isomerisation and is converted into a mixture of D-Glucose, D-Mannose and D-Fructose. D-Glucose D-Mannose D-Fructose. Structure of D-Glucose Open chain structure : The reaction of glucose with HI to give hexane Hydroxylamine to form monoxime HCN to form cyanohydrin gives the existence to the open chain structure of glucose Cyclic structure of glucose : The open chain structure of glucose fails to explain No reaction with NaHSO3 and NH3 – even though – CHO is present. Glucose does not react with Grignard reagent. Negative test (for aldehydes) with Schiff's base. All the above observation indicates that free aldehydic group is not present. H H HO 1 H C CHOH CH2OH D-glucose – H+ CH O CH2OH H+ CH O CH2OH α-D-glucose CHOH or CHOH CHOH CH O CH2OH β-D-glucose α-D-glucose and β-D-glucose are anomers of each other. CH2OH CH2OH O H H H 1 OH H OH OH H OH O H OH H OH H OH H H OH α-D-glucose β-D-glucose α-D-glucose and β-D-glucose on treatment with CH3OH in presence of dry HCl gas forms methyl α-D-glucoside and methyl β-D-glucoside. CHO H C OCH3 H3CO C H H C OH HO C H H C OH H C OH CH3OH HCl H C HO C H C H C OH H & OH O H C HO C H C H C OH H OH O CH2OH CH2OH Methyl α-D-glucoside CH2OH Methyl β-D-glucoside Glucose ring can be easily broken up by strong reagents like HCN, NH2OH and C6H5NHNH2. Mutarotation : The α and β anomers of glucose are obtained from crystallisation at 30°C and 98°C respectively. If either of the two forms are allowed to stand, the specific rotation of the solution changes slowly and reaches a constant value. The spontaneous change is specific rotation of an optically active compound is called mutarotation. α-D-glucose Eq. mixture β-D-glucose +111° +52.5° +19° Disaccharides Disaccharides are composed of two molecules of monosaccharides linked by glycosidic linkage. The disaccharides may be reducing or non reducing in nature depending upon linkage. H O/H+ Sucrose (C H O ) 2 Glucose + Fructose 12 22 11 H O/H+ Lactose (C H O ) 2 Glucose + Galactose 12 Maltose (C 22 11 H O H O/H+ ) 2 Glucose + Glucose 12 22 11 Structure of Sucrose, Lactose and Maltose Sucrose 6CH2OH H 5 O H H 4 OH H 1 β-linkage O O 2 OH CH2OH H HO 3 2 H OH α-linkage H HOH2C H OH Glucose unit Fructose unit Lactose CH2OH HO O H β-linkage H OH 3 O OH OH H 1 OH H 1 4 H H H O H 5 H OH CH2OH 6 Maltose CH2OH O H H 1 OH H HO H OH α -linkage H OH Polysaccharides : In polysaccharides thousands of monosaccharide units are joined together by glycosidic linkage. Starch : (C6H10O5)n H+/H O (C6H10O5)n C12H22O11 C6H12O6 Starch Maltose D-glucose Starch does not reduce Fehling’s solution or Tollen’s reagent. Starch does not form an Osazone. Starch is a mixture of two polysaccharides i.e., amylose and amylopectin. Cellulose : (C6H10O5)n Cellulose is a straight chain polysaccharide composed of only D-glucose units. Cellulose does not reduce Tollen’s reagent or Fehling’s solution. AMINO ACIDS Amino acids are small molecules made of carbon, hydrogen, oxygen and nitrogen and in some cases also sulphur. A free amino group is basic, a free carboxyl group is acidic. Lysine and arginine are Basic Amino Acids because they carry two amino groups and one carboxyl group is acidic. Glutamic acid (glutamate) and aspartic acid (aspartate) contain one amino and two carboxyl groups each and are classified as Acidic Amino Acids. Alanine, glycine, valine and phenylalanine are Neutral Amino Acids as these contain one amino and one carboxyl group R CH COOH NH2 Lysine Side chains Side chain of a basic and an acidic amino acids COOH H2N — C — H CH3 Alanine (nonpolar) COOH H2N — C — H CH2 CH2 COOH Glutamic acid (polar) COOH H2N — C — H H2COH Serine (polar) Examples of polar and nonpolar amino acids Amino Acids which occur in Proteins Glycine, alanine, serine, cysteine, aspartic acid, glutamic acid, asparagine, glutamine, methionine, threonine, valine, leucine, isoleucine, lysine, histidine, arginine phenylalanine, tyrosine, tryptophan and proline. PROTEINS Proteins are polyamides formed from amino acids. The α-carbon atom of the amino acids is asymmetric and show optical isomerism (stereo). Proteins consist mainly of l isomers of amino acids. These are 20 commonly occurring amino acids in proteins. Amino acids form zwitter ion. Lack of essential amino acids in diet can cause diseases such as Kwashiorkar. Peptide Bond and Structure of Proteins Amino acids are joined together by an amide linkage called peptide bond. Proteins are long polymers of amino acids linked by peptide bonds (polypeptides). The sequence in which the amino acids are arranged in a protein is called the primary structure. The secondary structure arises due to the regular folding of the backbone of the polypeptide chain due to intramolecular hydrogen bonding between the carboxyl and amino groups. The tertiary structure is the three-dimensional structure of globular proteins. It arises due to folding and superimposition of various secondary structural elements. ENZYMES Enzymes are biological catalysts which increase the rate of biochemical reactions even under mild conditions of temperature and pH of living organisms. Properties of Enzymes : They speed up reactions up to ten million times compared to the uncatalyzed reactions. They are very specific in their action on substrates and each enzyme catalyzes only specific type of reaction. They are active at moderate temperature and pH. The action of enzymes are inhibited by various organic and inorganic molecules. Enzymes and Diseases : Certain diseases are caused by enzyme deficiencies. The congenital disease phenylketone urea, is due to a deficiency of the enzyme phenylanine hydroxylase. Albinism is another disease caused due to deficiency of an enzyme tyrosinase. Many heart attacks are caused by blood clot formation in a coronary artery. The enzyme streptokinase is used to dissolv e the clot. NUCLEIC ACIDS Nucleic acids play an essential role in transmission of the hereditary characteristics and the biosynthesis of proteins. There are two classes of nucleic acids : DNA (deoxyribonucleic acid) and RNA (ribonucleic acid). Nucleic acids are the long polymers in which the monomeric units are nucleotides. The nucleotides are made up of three chemical components; a nitrogen containing heterocyclic base, a five-carbon sugar and a phosphoric acid. In nucleic acids, the individual nucleotides are linked through phosphate groups to give rise to long polynucleotide structures. Structure of DNA DNA consists of two strands of polynucleotides coiled around each other in the form of a double helix. Functions of Nucleic Acids Replication : The genetic information for the cell is contained in the sequence of the bases A, T, G and C in the DNA molecule. The DNA sequence that codes for a specific protein or polypeptide is called a GENE and thus every protein in a cell has a corresponding gene.The relation between the nucleotide triplets and the amino acids is called the GENETIC CODE. VITAMINS Vitamins are organic compounds necessary for normal health but cannot be synthesised in human body. Deficiency of vitamins causes many disorders and diseases. Vitamins B and C are water soluble while vitamins A, D, K and E are fat soluble. ❑ ❑ ❑