Biological Molecules PDF

Lec 2 Biological Molecules = Biomolecules Biomolecules are essential molecules for all living organisms. Have unique characteristics and properties that show how they contribute to the structure and function of...

Lec 2 Biological Molecules = Biomolecules Biomolecules are essential molecules for all living organisms. Have unique characteristics and properties that show how they contribute to the structure and function of the cells.  Biomolecules consist mainly of 6 elements: Carbon Hydrogen Oxygen Nitrogen Sulphur Phosphorus Biomolecules are very large molecules of many atoms that are covalently bound together. Four Classes of Biomolecules  Biomolecules include carbohydrate, lipid, protein, nucleic acid and water molecules. Water is the solvent of life and contributes to more than 60% of the weight. This is followed by protein (mostly in muscle) and lipid (mostly in adipose tissue). The carbohydrate content is rather low which is in the form of glycogen. The biomolecules is made of smaller components called monomers. Monomers and Polymers of Biomolecules. Biological Monomer Polymer Molecules Carbohydrate Monosaccharides Polysaccharides Proteins Amino Acids Polypeptide Lipids Fatty Acid, Lipid Glycerol Nucleic Acids Nucleotide Nucleic Acids Another definition of Biomolecules: Biomolecules: any molecule that is involved in the metabolic processes of living organisms. What Are Metabolic Processes? Is the sum of chemical reactions that occur throughout the body within each cell and that provide the body with energy.  These reactions are controlled by the presence or absence of enzymes which act as catalysts. Metabolic pathways can be described as a series of chemical reactions that: Start with a substrate Finish with an end product Metabolic processes = metabolism. Metabolism is a balancing act involving two kinds of activities that go on at the same time: building up body tissues and energy stores (called anabolism) breaking down body tissues and energy stores to get more fuel for body functions (called catabolism)  Types of Metabolic Reactions 1- Anabolic reactions build complex molecules from simpler subunits (for organic monomers, this involves condensation polymerization). 2- Catabolic reactions break down complex molecules into smaller components (for organic polymers, this involves hydrolysis reactions)  Anabolism Catabolism This is building process This is a breaking down process Small molecules combine Large molecule break into together to form larger smaller molecules molecules Energy required for the Release energy when bonds formation of chemical bonds are broken (Exerogenic) (Endrogenic) Involves creation of bonds Involves breaking of bonds by reduction or condensation by oxidation or hydrolysis reactions reactions Anabolic Reaction Catabolic Reaction  Stages of catabolism of Macromolecules 1st Stage : Digestion& Absorption 2nd Stage: Formation of Acetyl COA 3rd stage: Krebs's cycle ATP Respiratory chain Cellular Respiration: Harvesting Chemical Energy  To use ATP for energy, the cell cleaves the chemical bond between phosphate groups. This bond, called a phosphodiester bond, holds a lot of energy. Why Is It So Important? There are basically three reasons why ATP is so important in biology: 1. It’s the molecule the body uses directly as energy. 2. Other forms of chemical energy get turned into ATP. 3. It’s easy to recycle, so a cell can use a single molecule again and again. It’s often called the “energy currency” of metabolism and cells. ATP acts as an energy link between the catabolism and anabolism in the biological system. How Do Cells Keep Metabolic Reactions in Balance?  Cells employ various mechanisms to regulate their metabolism. Three primary methods through which cells control metabolic processes include: – Managing substrate availability, – Modulating enzyme concentration, – Regulating enzyme activity.  Elements Simplest form of a substance. Cannot broken down into more simpler form. 25 out of the nature elements are essential to life. 98-99% of the body is composed of 6 major elements C, H, O, N, S, P. Other than C, H, O, N, P, S are also common, Metal ions (e.g., K+, Na+, Ca++, Mg++, Zn++, Fe++) play important roles in metabolism  Compounds A substance composed of 2 or more elements that are chemically bonded together. Can be classified into inorganic or organic compounds. Functional Groups determine chemical properties of compounds. Several Functional groups in a single biomolecule Major Types of Chemical bonds in Biomolecules Ester Bond Disulphide Bond Peptide Bond Glycosidic Bond Ester Bond Disulfide Bond ‘ Peptide Bond Glycosidic Bond  Major Types of Chemical reactions occur in the cell Group transfer Oxidation-reduction Rearrangement Cleavage Condensation Group transfer Oxidation-reduction Rearrangement Cleavage Condensation