Overview of Metabolism and The Provision of Metabolic Fuels (Biochemistry) PDF

‫ﺟﺎﻣﻌﮫ اﻻﺳراء‬ Universty of Al-esrra Collage of Pharmacy Overview of Metabolism and The Provision of Metabolic Fuels Prepared by Dr...

‫ﺟﺎﻣﻌﮫ اﻻﺳراء‬ Universty of Al-esrra Collage of Pharmacy Overview of Metabolism and The Provision of Metabolic Fuels Prepared by Dr. Alaa Alnoori Dr Tariq Alhakeem Lec. 1: Biochemistry 3rd year 2nd semester 29:01:2024  The chemistry of life is organized into metabolic pathways Ø Metabolism: The sum of all the chemical processes occurring in an organism at one time Ø The totality of an organism's chemical reaction is called metabolism Ø A cell metabolism is an elaborate road map of the chemical reaction in the cell Ø Metabolic pathways alter molecules in a series of steps Ø Enzymes selectively accelerate each step  Pathway classification Ø Individual enzymic reactions were analyzed in an effort to explain the mechanisms of catalysis. However, in cells, these reactions rarely occur in isolation but rather are organized into multistep sequences called pathways, such as that of glycolysis. Ø These are collectively called metabolism, which is the sum of all the chemical changes occurring in a cell, a tissue, or the body. Ø Most pathways can be classified as either catabolic (degradative) or anabolic (synthetic).  Type of metabolic pathways: Ø Catabolic Pathways Release energy by breaking down complex molecules into simpler ones, such as proteins, polysaccharides, and lipids, to a few simple molecules, for example, CO2, NH3 (ammonia), and water. C6H12O6 + 6O2 à 6CO2 + 6H2O + energy Ø Anabolic Pathways Consume energy by building molecules Photosynthesis uses energy 6CO2 + 6H2O energy à C6H12O6 + 6O2  Comparison of catabolic and anabolic pathways Ø Catabolic pathways involve the degradation (or breakdown) of complex molecules into simpler ones.. Ø Anabolic pathways require an input of energy to synthesize complex molecules from simpler ones. Synthesizing sugar from CO2 is one example. Other examples are the synthesis of large proteins from amino acid building blocks Ø These biosynthetic processes are critical to the life of the cell, take place constantly, and demand energy provided by ATP and other high-energy molecules like NADH  Catabolic pathway Ø Hydrolysis of complex molecules: In the first stage, complex molecules are broken down into their component building blocks. For example, proteins are degraded to amino acids, poly-saccharides to monosaccharides, and fats (triacyl glycerols) to free fatty acids and glycerol. Ø Conversion of building blocks to simple intermediates: In the second stage, these diverse building blocks are further degraded to acetyl coenzyme A (CoA) and a few other, simple molecules. Ø Oxidation of acetyl CoA: The tricarboxylic acid (TCA) cycle is the final common pathway in the oxidation of fuel molecules that produce acetyl CoA.  Anabolic pathways Ø Anabolic pathways Anabolic reactions combine small molecules, such as amino acids, to form complex molecules, such as proteins. Ø Anabolic reactions require energy (are endergonic), which is generally provided by the breakdown of ATP to adenosine diphosphate (ADP) and inorganic phosphate (Pi ).  Protein metabolism Ø It is important to know that the chemical reactions of metabolic pathways don’t take place spontaneously. Each reaction step is facilitated, or catalyzed, by a protein called an enzyme. Ø Enzymes are important for catalyzing all types of biological reactions—those that require energy as well as those that release energy. Ø Catalyst—chemical agent that speeds up a chemical reaction without being consumed by the reaction  Enzymes speed up metabolic reaction Ø An enzyme is a catalytic protein. Ø Catalytic proteins that speed up metabolic reactions by lowering energy barriers Ø Enzymes regulate the movement of molecules through metabolic pathways Ø The chemical reaction between molecules involves both bond-breaking and bond- forming  The Activation Energy Barrier Ø Every chemical reaction between molecules involves bond breaking and bond forming. Ø The initial energy needed to start a chemical reaction is called the free energy of activation, or activation energy (EA). Ø Activation energy is often supplied in the form of heat from the surroundings  Fat metabolism Ø Fat metabolism is a biological metabolic process that breaks down ingested fats into fatty acids and glycerol after which into simpler compounds that can be used with the aid of cells of the body. Ø These compounds ultimately get processed and broken down to produce energy for the body's cells  Carbohydrate metabolism Ø Carbohydrate metabolism is the whole of the biochemical processes responsible for the metabolic formation, breakdown, and interconversion of carbohydrates in living organisms. Ø Carbohydrates are central to many essential metabolic pathways Ø Humans can consume a variety of carbohydrates, digestion breaks down complex carbohydrates into a few simple for metabolism. Ø Glucose is distributed to cells in the tissues, where it is broken down or stored as glycogen  Carbohydrate chemical structure Ø Hydrolysis of sucrose by the enzyme sucrase is an example of an enzyme-catalyzed reaction  Integrating metabolic pathways Ø Metabolic pathways interconnect glycogen, fat and protein reserves to store and retrieve ATP and glucose Ø ATP is the immediate source of energy for cellular processes Ø Glucose is essential for the metabolism of fat and the providing ATP in red cells and brain Ø Glucose cannot be made from fat  Generalities of metabolism Ø ATP and glucose levels must be reasonably constant Ø The utilizing of fat for energy required carbohydrate Ø Synthesis and degradative pathways don’t happen at the same time Ø Low energy levels turn on glycolysis and lipolysis Ø Low glucose levels turn on gluconeogenesis and protein degradation Thank you for your listening