METABOLISM - Sum total of all chemical reactions in a living organism Chemical processes to provide energy, growth substance and cell repair - CATEGORIES CATABOLISM - - large biochemical molecules are broken down ro smaller ones energy is released ANABOLISM - - small molecules are joined to form larger ones requires energy ADP and ATP – key components of metabolic pathways Net energy produced is used for cellular reactions ➢ - FLAVIN ADENINE DINUCLEOTIDE (FAD) Coenzyme needed for numerous redox reactions OXIDIZED FORM Reduced form is FADH2 Oxidizing agent in conversion of alkane to an alkene ➢ - NICOTINAMIDE ADENINE DINUCLEOTIDE (NAD) A coenzyme Reduced form is NADH 3 subunit structure: → Nicotinamide-ribose-ADP → 6 subunit structure (nico-ribo-phosphos-ribo-adenine) Serves as an oxidizing agent in the oxidation of secondary alcohol to give ketone METABOLIC PATHWAY (MP) – series of consecutive biochemical reactions used to convert a starting material into an end product - TYPES: ➢ Linear ➢ Cyclic ➢ COENZYME A - Derivative of vitamin B - Active in the form of sulfhydryl group (-SH group) in the ethanethiol subunit - Acetyl-CoA (acetylated) IMPORTANT NUCLEOTIDE-CONTAINING COMPOUNDS IN MP ➢ HIGH-ENERGY PHOSPHATE COMPOUNDS – have greater free energy of hydrolysis than a typical compound - Contains strained bond (~) – they have at least one reactive bond - Less energy needed to break the bonds - Free energy released is greater than 6.0 kcal/mole ➢ ADENOSINE PHOSPHATES (ATP, ADP, & AMP) AMP – RNA’s structural component - Phosphate groups connected to AMP (thru strained bonds) require less than normal energy to hydrolyze them CLASSIFICATION OF METABOLIC INTERMEDIATE COMPOUNDS BIOCHEMICAL ENERGY PRODUCTION STEP 1: DIGESTION → Begins in the mouth, continues in the stomach, completed in the small intestine - Resulting small molecules can cross intestinal membrane in to the blood → End products are absorbed in blood and transported to body’s cells - Glucose and monosaccharides - Amino acids - Fatty acids and glycerol STEP 2: ACETYL GROUP FORMATION → Small molecules from stage 1 are further oxidized → Reactions occur in cytosol (glucose metabolism) and mitochondria (fatty acid metabolism) → Primary products: two-carbon acetyl units (attached to coenzyme A = Acetyl CoA) and NADH → End product is acetyl CoA STEP 3: CITRIC ACID CYCLE → → → Takes place in mitochondria → Some are lost energy in the form of heat Acetyl group is oxidized = CO2 and energy Most energy is trapped and carried by NADH and FADH2 to the fourth stage STEP 4: ETC PHOSPHORYLATION and OXIDATIVE → Happens in mitochondria → NADH and FADH2 are oxidized and releases H+ that is transported to mitochondria’s intermembrane space → Electrons transfer to O2 and will reduce to H2 → H+ reenters the mito-matrix and drive ATPsynthase reaction to produce ATP – primary energy carrier in metabolic pathways Common Metabolic Pathways – sum of reactions that occur in the citric acid cycle, ETC, and oxidative phosphorylation. CHEMICAL PROCESS PRIOR TO METABOLISM ➢ Digestion – breakdown of food by hydrolysis into simpler chemical units that can be used by cells in metabolic processes ➢ Absorption – process where digested molecules are transferred to bloodstream and ultimately into the cells - Takes place in small intestine thru villi (supplied w/ network of blood vessels and a central lymph vessel)