NEETClass 11thClass 12thClass 12th PlusJEEClass 11thClass 12thClass 12th PlusClass 6-10Class 6thClass 7thClass 8thClass 9thClass 10thOnline CoursesDistance LearningInternational OlympiadNEETClass 11thClass 12thClass 12th PlusJEE (Main+Advanced)Class 11thClass 12thClass 12th PlusJEE MainClass 11thClass 12thClass 12th PlusClass 6-10Class 6thClass 7thClass 8thClass 9thClass 10thKCET/MHT-CETKCETMHT-CETNEET20262025202420232022JEE20262025202420232022Class 6-1020262025JEE MainPrevious Year PapersSample PapersMock TestResultAnalysisSyllabusExam DatePercentile PredictorAnswer KeyCounsellingEligibilityExam PatternJEE MathsJEE ChemistryJEE PhysicsJEE AdvancedPrevious Year PapersSample PapersMock TestResultAnalysisSyllabusExam DateAnswer KeyEligibilityExam PatternRank PredictorNEETPrevious Year PapersSample PapersMock TestResultAnalysisSyllabusExam DateCollege PredictorAnswer KeyRank PredictorCounsellingEligibilityExam PatternBiologyNCERT SolutionsClass 6Class 7Class 8Class 9Class 10Class 11Class 12TextbooksCBSEClass 12Class 11Class 10Class 9Class 8Class 7Class 6SubjectsSyllabusNotesSample PapersQuestion PapersICSEClass 10Class 9Class 8Class 7Class 6State BoardBiharKarnatakaMadhya PradeshMaharashtraTamilnaduWest BengalUttar PradeshOlympiadMathsScienceEnglishSocial ScienceNSOIMONMTCTALLENTEXASATInstant Online ScholarshipAIOT(NEET)ALLEN for SchoolsAbout ALLENBlogsNewsCareersRequest a call backBook a demo
1.0Proteins and Amino Acids
The term "protein" originates from the Greek word "proteios," which translates to primary or of prime importance. Proteins are fundamental molecules in living organisms, essential for various biological functions.
Amino Acids
Amino acids, the building blocks of proteins, contain amino (–NH2) and carboxyl (–COOH) functional groups. They are characterized by the presence of both an amino group and a carboxyl group attached to the same carbon atom, known as the α-carbon. When proteins are hydrolyzed, they break down into their constituent amino acids. While amino acids can contain other functional groups, those that are derived from proteins are primarily α-amino acids.
Classification of α-Amino Acids
α-Amino acids can be classified into three main categories based on the properties of their side chains:
Acidic Amino Acids: Acidic amino acids possess a carboxyl group in their side chain, rendering them acidic in nature.
Examples include:
- Aspartic acid (Asp)
- Glutamic acid (Glu)
Basic Amino Acids: Basic amino acids carry a positively charged amino group in their side chain at physiological pH.
Examples include:
- Lysine (Lys or K)
- Arginine (Arg or R)
- Histidine (His or H)
Neutral Amino Acids:
- Neutral amino acids have side chains that are neither acidic nor basic at physiological pH.
- They can be further categorized based on the properties of their side chains, such as polar, nonpolar, aromatic, etc.
Examples include:
Structure of Proteins
Proteins are intricate molecules, serving essential roles in various biological processes. They are composed of chains of α-amino acids linked together by peptide bonds or peptide linkages.
- Peptide Bond Formation: Chemically, a peptide bond is an amide linkage formed between the carboxyl (-COOH) group of one amino acid and the amino (-NH2) group of another. When two amino acid molecules react, the amino group of one amino acid combines with the carboxyl group of the other, resulting in the elimination of a water molecule. This process is called condensation or dehydration synthesis. The resulting bond is a peptide bond (-CO-NH-), which joins the α-carbons of adjacent amino acids.
- Polypeptide Chains: The repetitive formation of peptide bonds between successive amino acids results in the formation of a polypeptide chain. These chains can vary in length and sequence, giving rise to the diverse structures and functions of proteins.
- Primary Structure: The primary structure of a protein refers to the linear sequence of amino acids in the polypeptide chain. It is determined by the specific order of amino acids linked together by peptide bonds. The sequence of amino acids is encoded by the genetic information stored in DNA.
- Secondary Structure: The secondary structure of a protein arises from interactions between amino acids that are close in the primary sequence. Common secondary structures include α-helices and β-sheets, stabilized by hydrogen bonds between backbone atoms.
- Tertiary Structure: The tertiary structure of a protein refers to the overall three-dimensional arrangement of the polypeptide chain. It is dictated by interactions between amino acid side chains, including hydrogen bonds, disulfide bonds, hydrophobic interactions, and electrostatic interactions.
- Quaternary Structure: In some cases, proteins consist of multiple polypeptide chains that come together to form a functional protein complex. The arrangement of these subunits is referred to as the quaternary structure.
2.0Vitamins
Vitamins are essential organic compounds that are required in small amounts in the diet to support various biological functions necessary for optimal growth and health maintenance in organisms.
1. Fat soluble vitamins : A, D, E and K
2. Water soluble vitamins : B and C
S.N. | Vitamin | Chemical name | Deficiency disease | Source |
1 | Vitamin-A | Retinol | Xerophthalmia (Hardening of cornea of eye) and Night blindness | Fish liver oil, Carrot, Butter, Milk |
2 | Vitamin-B1 | Thiamine | Beri-beri (Loss of appetite and retarded growth), Paralysis | Yeast, Milk, Green vegetables, Cereals |
3 | Vitamin-B2 | Riboflavin | Cheilosis (Fissuring at corners of mouth and lips) | Milk, Egg white, Liver, Kidney |
4 | Vitamin-B6 | Pyridoxine | Convulsion | Milk, Yeast, Egg yolk, Cereals |
5 | Vitamin B12 | Cyanocobalamine | Pernicious anaemia (RBC deficient in Hb) | Fish, Meat, Egg, curd |
6 | Vitamin-C | Ascorbic acid | Scurvy (bleeding gums) | Citrus fruits, Amla Green leafy vegetables |
7 | Vitamin-D | Calciferol | Rickets (Bone deformities in children) Osteomalacia (soft bones & joint pain in adults) | Exposure to sunlight, Fish, Egg yolk |
8 | Vitamin-E | Tocoferol | Increased fragility of RBC muscular weakness | Vegetable oil, Sunflower oil |
9 | Vitamin-K | Phylloquinone | Increased blood clotting time | Green leafy vegetables |
3.0Nucleic Acids
Nucleic acids are complex biomolecules that play essential roles in the storage, transmission, and expression of genetic information in living organisms. They are polymers made up of repeating units called nucleotides.
Structure of Nucleic Acids
Nucleic acids, the carriers of genetic information in living organisms, consist of nucleotides, which are the building blocks of these molecules.
Nucleoside: A nucleoside is formed by the attachment of a nitrogenous base to the 1' position of a sugar molecule. The carbons in the sugar molecule are numbered as 1', 2', 3', etc., to distinguish them from the atoms in the base. Nucleosides serve as the basic units for the construction of nucleotides.
Nucleotide: When a nucleoside is linked to a phosphoric acid group at the 5'-position of the sugar moiety, it forms a nucleotide. The addition of the phosphate group gives the nucleotide its characteristic structure and functionality. Nucleotides are the fundamental building blocks of nucleic acids, such as DNA and RNA.
Types of Nucleic Acids
Nucleic acids are primarily categorized into two types:
Deoxyribonucleic Acid (DNA):
- DNA serves as the repository of genetic information in living organisms.
- It is a double-stranded helical molecule composed of nucleotides.
- Each nucleotide consists of a sugar molecule (deoxyribose), a phosphate group, and one of four nitrogenous bases: adenine (A), thymine (T), cytosine (C), and guanine (G).
- The sequence of these nitrogenous bases encodes the genetic instructions for the development, functioning, and reproduction of organisms.
Ribonucleic Acid (RNA):
- RNA plays various crucial roles in protein synthesis, gene regulation, and other cellular processes.
- Unlike DNA, RNA is typically single-stranded, although it can fold into complex secondary and tertiary structures.
- Similar to DNA, RNA is composed of nucleotides, each containing a ribose sugar, a phosphate group, and one of four nitrogenous bases: adenine (A), uracil (U), cytosine (C), and guanine (G).
- RNA molecules are involved in translating the genetic information stored in DNA into functional proteins through the process of transcription and translation.
Also Read: