TLDR;
This video provides a comprehensive overview of biomolecules, covering their chemical composition, classification, and functions. It begins with an introduction to the importance of biomolecules in living organisms and their connection to evolution. The discussion includes chemical analysis, the distinction between biomicro and biomacromolecules, and detailed explanations of carbohydrates, lipids, proteins, and nucleic acids. The video emphasizes the structural and functional aspects of these molecules, highlighting their roles in various biological processes.
- Biomolecules are essential for life, playing key roles in cellular structure and function.
- The video covers chemical analysis, biomicro vs. biomacromolecules, carbohydrates, lipids, proteins, and nucleic acids.
- Key concepts include glycosidic bonds, peptide bonds, and the different levels of protein structure.
Introduction [0:00]
The video introduces the topic of biomolecules, emphasizing its importance as one of the most significant chapters for NEET preparation. It highlights that a minimum of four questions can be expected from this chapter. Additionally, understanding biomolecules is crucial for grasping the nucleic acid part in the "Molecular Bases of Inheritance" chapter. The presenter advises students to study biomolecules before moving on to genetics and biotechnology for a comprehensive understanding.
Biomolecules and Evolution [4:05]
The discussion starts by defining "bio" as related to living organisms and connects the chapter to the concept of evolution, beginning with the Big Bang Theory proposed by George Lemaître. It mentions the widely accepted Oparin and Haldane theory on the origin of life, which includes chemical and biological evolution. The process involves atoms forming molecules, progressing from inorganic to complex organic compounds, and eventually aggregating into protocells. The presenter emphasizes that cells are made up of organic and inorganic components, highlighting the importance of both biology and chemistry in understanding life processes.
Chemical Composition: Analyzing Living and Non-Living Matter [10:52]
The chapter starts with chemical composition, focusing on how to analyze it. Elemental analysis reveals similar elements in living organisms (plant, animal tissues, microbial paste) and non-living matter (Earth's crust), with carbon and hydrogen being more abundant in living organisms. The process involves grinding a living tissue in trichloroacetic acid using a mortar and pestle to create a slurry. This slurry is then strained through cheesecloth to separate it into filtrate (acid-soluble pool) and retentate (acid-insoluble pool).
Acid Soluble vs. Insoluble Pools [19:02]
The filtrate, or acid-soluble pool, contains substances with a molecular weight less than 1,000 Daltons, including biomicro molecules, inorganic compounds like sulfates and phosphates, and thousands of organic compounds. This pool roughly represents the cytoplasmic composition. The retentate, or acid-insoluble pool, contains substances with a molecular weight above 10,000 Daltons, primarily biomacro molecules like proteins, polysaccharides, and nucleic acids, but excludes lipids. Lipids, although biomicro molecules, are part of the acid-insoluble fraction because they are insoluble in water and form insoluble vesicles when cells are broken.
Analysis of Inorganic Compounds [32:46]
The analysis of inorganic compounds involves taking a living tissue, measuring its wet weight, and then burning it to evaporate all water and carbon compounds. The remaining ash contains inorganic elements like calcium, magnesium, sulfate, and phosphate. This ash represents the inorganic composition of the living tissue.
Chemical Analysis and Elemental Composition Tables [36:04]
The video emphasizes the importance of understanding tables in the NCERT textbook, particularly those detailing chemical analysis and elemental composition. It compares the elemental composition of the Earth's crust and the human body, noting that oxygen is abundant in both. However, silicon is abundant in the Earth's crust but negligible in the human body. In the human body, after oxygen, carbon and nitrogen are the most abundant elements.
Primary and Secondary Metabolites [42:15]
The discussion transitions to primary and secondary metabolites. Primary metabolites have identifiable functions and play known roles in normal physiological processes, such as amino acids, sugars, and chlorophylls involved in photosynthesis, respiration, and protein/lipid metabolism. Secondary metabolites, such as alkaloids, flavonoids, rubber, essential oils, antibiotics, colored pigments, scents, and gums, do not have identifiable roles but are important for the host organism and human welfare.
Carbohydrates: Introduction and Classification [58:49]
Carbohydrates are defined as hydrates of carbon, organic compounds containing carbon, hydrogen, and oxygen, with some also containing nitrogen and sulfur. Chemically, they are polyhydroxy aldehydes or ketones. The ratio of carbon, hydrogen, and oxygen is 1:2:1. Carbohydrates are classified into monosaccharides, oligosaccharides, and polysaccharides based on hydrolysis products.
Monosaccharides: Structure and Properties [1:09:36]
Monosaccharides are the simplest sugars that cannot be further hydrolyzed. Their general formula is CN(H2O)N. They contain 3 to 7 carbon atoms and are highly soluble in water, sweet in taste, and have a reducing nature. Monosaccharides can occur in straight-chain (Fischer projection) and ring forms (pyranose and furanose). Examples include glucose, ribose, and deoxyribose.
Monosaccharides: Aldoses and Ketoses [1:22:10]
Monosaccharides are classified as aldoses or ketoses based on their functional group: aldehyde or ketone, respectively. Examples include glucose (aldose) and fructose (ketose). The video also explains alpha and beta glucose, which are anomers differing in the position of the hydroxyl group on the first carbon. Additionally, it describes epimers, which are isomers differing in the configuration around a single carbon atom.
Monosaccharides: Examples and Importance [1:40:06]
Glucose is highlighted as the main respiratory substrate and blood sugar. Fructose is known as fruit sugar and is the sweetest. Galactose is referred to as brain sugar and is a component of lactose. Ribose and deoxyribose are essential components of RNA and DNA, respectively, with deoxyribose lacking an oxygen atom at the second carbon.
Oligosaccharides: Disaccharides and Glycosidic Bonds [2:05:51]
Oligosaccharides are formed by the condensation of 2 to 10 monosaccharide units. Disaccharides, a type of oligosaccharide, include lactose (glucose + galactose), maltose (glucose + glucose), and sucrose (glucose + fructose). Monosaccharides are linked by glycosidic bonds, which involve dehydration. The video details the formation of glycosidic bonds, specifically 1-4 glycosidic linkages in maltose and lactose, and 1-2 glycosidic linkages in sucrose.
Disaccharides: Lactose, Maltose, and Sucrose [2:13:02]
Maltose is composed of two glucose units with a 1-4 glycosidic linkage. Lactose consists of glucose and galactose, also with a 1-4 glycosidic linkage. Sucrose, or table sugar, is made of glucose and fructose with a 1-2 glycosidic bond and is a non-reducing sugar.
Polysaccharides: Structure and Function [2:29:15]
Polysaccharides are long chains of more than 10 monosaccharides, also known as glycans. They are non-sweet, tasteless, and insoluble in water. Polysaccharides can be nutritive or structural. They are classified as homopolysaccharides (same type of monomers) or heteropolysaccharides (different types of monomers). Examples of homopolysaccharides include glycogen, starch, cellulose, inulin, and chitin. Heteropolysaccharides include hyaluronic acid, heparin, hemicellulose, pectin, and chondroitin.
Polysaccharides: Cellulose, Inulin, and Chitin [2:36:16]
Cellulose is a structural polysaccharide found in plant cell walls, composed of beta-D-glucose units with beta 1-4 glycosidic linkages. Inulin is a polymer of fructose with 1-2 glycosidic linkages, stored in the roots of Dahlia and artichoke, and used to check the glomerular filtration rate (GFR). Chitin is a homopolysaccharide made of N-acetylglucosamine (NAG) and is a component of fungal cell walls and the exoskeleton of insects.
Polysaccharides: Glycogen and Starch [2:41:18]
Glycogen, also known as animal starch, is a branched polysaccharide made of glucose, serving as a stored food in animals and fungi. It has both 1-4 and 1-6 glycosidic linkages and gives a red color with iodine. Starch, the stored food in plants, consists of amylose (linear, unbranched, helically coiled) and amylopectin (branched). Amylose gives a blue color with iodine, while amylopectin gives a red color.
Lipids: Introduction and Properties [3:00:12]
Lipids are bio micro molecules with a molecular weight ranging from 18 to 800 Daltons, present in the acid-insoluble fraction. They are fats and their derivatives, composed of carbon, hydrogen, and oxygen, but not in a 1:2:1 ratio. Lipids are insoluble in water but soluble in organic solvents. They serve as a reservoir, shock absorber, and provide insulation.
Lipids: Classification and Structure [3:07:02]
Lipids are classified into simple lipids, conjugate or compound lipids, and derived lipids. Simple lipids are esters of alcohol with fatty acids, including neutral fats and waxes. Conjugate lipids are esters of fatty acids with alcohol containing other groups, such as phospholipids and glycolipids. Derived lipids, like cholesterol, have a long hydrocarbon ring with a hydrocarbon chain.
Simple Lipids: Glycerol and Fatty Acids [3:11:29]
Simple lipids are esters of fatty acids with alcohol, commonly glycerol (trihydroxy propane). Fatty acids contain a carboxylic group attached to an R group, which can be methyl, ethyl, or higher numbers of CH2 groups. The video explains esterification, where glycerol combines with fatty acids to form triglycerides, diglycerides, or monoglycerides.
Fatty Acids: Saturated vs. Unsaturated [3:22:51]
Fatty acids are classified as saturated or unsaturated. Saturated fatty acids have no carbon-to-carbon double bonds and are solid at room temperature (e.g., butter, ghee). Unsaturated fatty acids have one or more double bonds and are liquid at room temperature (e.g., mustard oil). Animal fats are mostly saturated, while plant fats are mostly unsaturated.
Saturated and Unsaturated Fatty Acids: Metabolic and Health Implications [3:28:54]
Saturated fatty acids are metabolically less reactive, tend to store in the animal body, and can increase blood cholesterol. Unsaturated fatty acids are metabolically more active and do not cause obesity or cholesterol deposition. Essential fatty acids, which cannot be synthesized by the body, are present in unsaturated fats. Examples of saturated fatty acids include stearic acid and palmitic acid, while unsaturated fatty acids include oleic acid, linoleic acid, linolenic acid, and arachidonic acid.
Phospholipids and Derived Lipids: Cholesterol and Steroids [3:39:31]
Phospholipids, a type of conjugate lipid, consist of glycerol, two fatty acids, phosphoric acid, and a nitrogenous compound. Lecithin is a common example. Derived lipids include cholesterol, which has a hydrocarbon ring and tail. Steroids, derived from lipids, are important for the formation of sex hormones.
Amino Acids: Structure and Properties [3:47:05]
Amino acids are bio micro molecules with a molecular weight less than 1,000 Daltons, making them part of the acid-soluble pool. They are the building blocks of proteins, joining via peptide bonds. There are 20 protein-forming amino acids, each with a unique one-word symbol. Amino acids are organic compounds with an amino group and a carboxylic group, and they are substituted methanes.
Amino Acids: Zwitterions and Classification [4:39:02]
Amino acids are amphoteric, meaning they have both acidic and basic groups. At the isoelectric point, they exist as zwitterions, which are electrically neutral but have both positive and negative charges. Amino acids are classified as acidic (more COOH than NH2), basic (more NH2 than COOH), or neutral. Examples of acidic amino acids are glutamic acid and aspartic acid, while basic amino acids include histidine, arginine, and lysine.
Amino Acids: Aromatic and Essential [4:48:20]
Glycine is the simplest amino acid, while tryptophan is the most complex. Tyrosine, tryptophan, and phenylalanine are aromatic amino acids. Tryptophan is required for auxin formation, and tyrosine is essential for melanin formation. Essential amino acids, which cannot be synthesized by the body, must be part of the diet. The trick to remember them is "Private Tim Hall."
Proteins: Structure and Denaturation [4:59:28]
Proteins are biomacro molecules and heteropolymers of amino acids. Amino acids join via peptide bonds to form polypeptides, which then form proteins. Proteins have four levels of structure: primary, secondary, tertiary, and quaternary. Primary structure is the linear sequence of amino acids. Secondary structure involves alpha helices and beta-pleated sheets. Tertiary structure gives a 3D view and is biologically active. Quaternary structure involves the assembly of multiple polypeptide chains. Denaturation of proteins involves changes in temperature or pH, disrupting hydrogen bonds and causing the protein to lose its 3D structure.
Proteins: Examples and Ramachandran Plot [5:05:15]
Collagen is the most abundant protein in the animal world, while rubisco is the most abundant protein in the biosphere. Other examples include trypsin, insulin, antibodies, and receptors. The Ramachandran plot is a graph used to analyze allowed conformations of proteins.
Nucleic Acids and Enzymes [5:31:00]
Nucleic acids are polymers of nucleotides, consisting of a nitrogenous base, sugar, and phosphoric acid. Enzymes, mostly proteins, will be discussed in a separate video.