Nutrition & Metabolism (1) (Fdt309) Lecture PDF

1 Shady ElShehawy ,2022 - [email protected] 10/11/2022  Nutrition & Metabolism (1) (Fdt309) Dietetic Program Introduction Professor Shady M. ElShehawy Professor of Food...

1 Shady ElShehawy ,2022 - [email protected] 10/11/2022  Nutrition & Metabolism (1) (Fdt309) Dietetic Program Introduction Professor Shady M. ElShehawy Professor of Food Science & Technology Food Industries Department, Faculty of Agriculture Mansoura University, Egypt 10/11/2022 Shady ElShehawy ,2022 - [email protected] 2 10/11/2022 Shady ElShehawy ,2022 - [email protected] 3 10/11/2022 Shady ElShehawy ,2022 - [email protected] 4 10/11/2022 Shady ElShehawy ,2022 - [email protected] 5 10/11/2022 Shady ElShehawy ,2022 - [email protected] 6  Our body is a wonderfully efficient factory. It accepts raw materials (food), burns some to generate power, uses some to produce finished goods, routes the rest to storage, and discard wastes and by- products. 10/11/2022 Shady ElShehawy ,2022 - [email protected] 7  Under normal nutrients supply, it hums along nicely with all process in balance. When supply exceeds demand, the body stores the excess raw materials in inventory. When supply fails to meet demand, your body draws on these stored materials to meet its needs. Our biological factory never stops, even though a storage or energy-production process may dominate, all our factory operations are always active. 10/11/2022 Shady ElShehawy ,2022 - [email protected] 8  Collectively, these processes are known as metabolism. Metabolism is a central theme in biochemistry; it keeps cells and organisms alive, by giving them the energy they need and the building blocks they require for growth and propagation. 10/11/2022 Shady ElShehawy ,2022 - [email protected] 9  Metabolism is the means by which the body derives energy and synthesizes the new molecules it needs from the fats, carbohydrates and proteins we eat as food, by enzymatic reactions helped by minerals and vitamins. To carry out metabolic processes, thousands of chemical reactions occur every moment in cells throughout our body. The most active metabolic sites include liver, muscle, and brain cells. 10/11/2022 Shady ElShehawy ,2022 - [email protected] 10  Chemical reactions: breaking and making covalent bonds 10/11/2022 Shady ElShehawy ,2022 - [email protected] 11  Breaking a covalent bond requires an initial input of energy in some form - normally as heat, but in some cases also light or other radiation. This is the activation energy of the reaction. The process of breaking a bond requires activation of the electrons forming the bond - a temporary movement of electrons from orbitals in which they have a stable configuration to orbitals further from the nucleus. 10/11/2022 Shady ElShehawy ,2022 - [email protected] 12 10/11/2022 Shady ElShehawy ,2022 - [email protected] 13  Electrons that have been excited in this way have an unstable configuration, and the covalent bonds they contributed to are weakened and broken. Electrons cannot remain in this excited state for more than a fraction of a second. Sometimes, they simply return to their original unexcited state, emitting the same energy as was taken up to excite them, but usually as a series of small steps, rather than as a single step. Overall, there is no change when this occurs. 10/11/2022 Shady ElShehawy ,2022 - [email protected] 14  More commonly, the excited electrons adopt a different stable configuration, by interacting with electrons associated with different atoms and molecules. The result is the formation of new covalent bonds, and hence the formation of new compounds. In this case, there are three possibilities, as shown as follow: 10/11/2022 Shady ElShehawy ,2022 - [email protected] 15 1. There may be an output of energy equal to the activation energy of the reaction, so that the energy level of the products is the same as that of the starting materials. Such a reaction is energetically neutral (Thermo-neutral). 10/11/2022 Shady ElShehawy ,2022 - [email protected] 16 2. There may be an output of energy greater than the activation of the reaction, so that the energy level of the products is lower than that of the starting materials. This is an Exothermic reaction - it proceeds with the output of heat. An exothermic reaction will proceed spontaneously once the initial activation energy has been provided. 10/11/2022 Shady ElShehawy ,2022 - [email protected] 17 3. There may be an output of energy less than the activation energy, so that the energy level of the products is higher than that of the starting materials. The solution will take up heat from its surroundings and will have to be heated for the reaction to proceed. This is an Endothermic reaction. 10/11/2022 Shady ElShehawy ,2022 - [email protected] 18 10/11/2022 Shady ElShehawy ,2022 - [email protected] 19 10/11/2022 Shady ElShehawy ,2022 - [email protected] 20  In general, reactions in which relatively large complex molecules are broken down to smaller molecules (catabolic reactions) are exothermic, whilst reactions that involve the synthesis of larger molecules from smaller ones (anabolic or biosynthetic reactions) are endothermic. 10/11/2022 Shady ElShehawy ,2022 - [email protected] 21 10/11/2022 Shady ElShehawy ,2022 - [email protected] 22  Enzymes and Metabolism 10/11/2022 Shady ElShehawy ,2022 - [email protected] 23  Enzymes are proteins that catalyze metabolic reactions. Proteins are linear polymers of amino acids. Any protein adopts a characteristic pattern of folding, determined largely by the amino acids in its sequence, and their interactions with each other and the surrounding environment. 10/11/2022 Shady ElShehawy ,2022 - [email protected] 24  This folding of the protein chain results in reactive groups from amino acids that may be widely separated in the primary sequence coming together at the surface and creating a site that has a defined shape and array of chemically reactive groups. This is the active site of the enzyme, which can be divided into two distinct domains: the binding site for the compounds that are to undergo reaction (the substrates) and the catalytic site. 10/11/2022 Shady ElShehawy ,2022 - [email protected] 25  Each enzyme mediates a particular biochemical reaction by functioning as a biological catalyst. Without enzymes, biological reactions would occur too slowly for cellular viability. 10/11/2022 Shady ElShehawy ,2022 - [email protected] 26  Enzymes operate by temporarily binding to their substrate molecule, imposing molecular modification and finally releasing the altered molecule (the reaction product). 10/11/2022 Shady ElShehawy ,2022 - [email protected] 27  Enzyme Structure 10/11/2022 Shady ElShehawy ,2022 - [email protected] 28  Although most enzymes are proteins, many contain small non-protein molecules as an integral part of their structure. These may be organic compounds or metal ions. In either case, they are essential to the function of the enzyme, and the enzyme has no activity in the absence of cofactor. 10/11/2022 Shady ElShehawy ,2022 - [email protected] 29  Cofactors are the helper molecules of enzymes. They are not proteins and are either inorganic or organic molecules. Coenzymes and prosthetic groups are two types of helper molecules. A coenzyme is an organic molecule which binds loosely or may be tightly, but not covalently with enzymes to help reactions. A prosthetic group is an organic molecule or a metal iron which binds tightly or covalently with the enzyme to assist chemical reactions. 10/11/2022 Shady ElShehawy ,2022 - [email protected] 30 10/11/2022 Shady ElShehawy ,2022 - [email protected] 31 10/11/2022 Shady ElShehawy ,2022 - [email protected] 32  Enzyme nomenclature 10/11/2022 Shady ElShehawy ,2022 - [email protected] 33  Enzymes are named according to the reaction they catalyze, so their reaction can often be inferred from the name. 10/11/2022 Shady ElShehawy ,2022 - [email protected] 34 10/11/2022 Shady ElShehawy ,2022 - [email protected] 35  Enzyme Reaction catalysed Kinase Addition of a phosphate group (‘phosphorylation’) Removal of a phosphate group (‘dephosphorylation’) Phosphatase Synthase Synthesis of the molecule preceding the ‘synthase’ Incorporation of one carbon dioxide molecule into the substrate molecule Carboxylase Removal of one carbon dioxide molecule from the substrate molecule Decarboxylase Oxidation of the substrate via transfer of (one or more) hydride ions (H-) to an electron acceptor, often NAD+ or FAD Dehydrogenase Rearrangement of existing atoms within the substrate molecule. The product has the same chemical formula as the substrate Isomerase Transfer of a functional group within the substrate molecule to a new location within the same molecule Mutase 10/11/2022 Shady ElShehawy ,2022 - [email protected] 36 10/11/2022 Shady ElShehawy ,2022 - [email protected] 37 38 10/11/2022 Shady ElShehawy ,2022 - [email protected]