Metabolic Processes Metabolic reactions are of two types: in anabolic reactions, larger molecules are constructed from smaller ones, a process requiring energy; 2. in catabolic reactions, larger molecules are broken down, releasing energy. The reactions of metabolism are often reversible.

Anabolism 1. Anabolism provides the substances needed for growth and repair. 2. These reactions occur by dehydration synthesis, removing a molecule of water to join two smaller molecules. 3. Polysaccharides, lipids, and proteins are constructed via dehydration synthesis. a. To form fats, glycerol and fatty acids bond. b. The bond between two amino acids is a peptide bond; two bound amino acids form a dipeptide, while many joined form a polypeptide.

Pg. 124 Dehydration synthesis of a carbohydrate

Pg. 124 Dehydration Synthesis of a Lipid

Pg. 125 Dehydration Synthesis of a Protein

Catabolism Catabolism breaks apart larger molecules into their building blocks. 2.These reactions occur by hydrolysis, wherein a molecule of water is inserted into a polymer which is split into two smaller molecules.

ATP Hydrolysis

WHY WE NEED ENZYMES

Catabolic Anabolic

Control of Metabolic Reactions: A.Enzymes control the rates of all the metabolic reactions of the cell. B.Enzyme Action 1.Enzymes are complex proteins that function to lower the activation energy of a reaction so it may begin and proceed more rapidly. Enzymes are called catalysts. 2.Enzymes work in small quantities and are recycled by the cell. 3.Each enzyme is specific, acting on only one kind of substrate. 4. Active sites on the enzyme combine with the substrate and a reaction occurs. 5.The speed of enzymatic reactions depends on the number of enzyme and substrate molecules available.

Fig. 4.04a Pg. 126

Fig. 4.04c

Enzyme catalyzed reaction Slide number: 2 Substrate molecule Active site Enzyme molecule Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

Enzyme catalyzed reaction Slide number: 3 Enzyme-substrate complex Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

Enzyme catalyzed reaction Slide number: 4 Product molecules Unaltered enzyme molecule Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

Enzyme catalyzed reaction Slide number: 1 Substrate molecule Active site Enzyme molecule Enzyme-substrate complex Product molecules Unaltered enzyme molecule Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

Concentration

Temperature

pH

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Co-factor – ions of elements such as copper, iron, zinc. Inorganic Co-enzyme – a co-factor that is organic, many are vitamins such as co-enzyme A Function – when they bind to enzymes, they activate them

Pg. 126 Metabolic Pathway Rate Limiting Enzyme

Creatine Phosphate – Phosphocreatine System 2. Anaerobic Glycolysis Energy is the ability to do work. All our energy needs must come from ATP’s So how is energy transferred to ATP’s from all the energy compounds in our body? 3 Ways the muscle cell can synthesize ATP Creatine Phosphate – Phosphocreatine System 2. Anaerobic Glycolysis 3. Aerobic Respiration – Oxidative Phosphorylation

Creatine Phosphate At rest cells store energy in creatine by transferring a phosphate and energy from an ATP, producing an ADP. This molecule is now known as phosphocreatine When energy is needed the phosphate breaks from the phosphocreatine and returns the energy to an ADP to become a usable ATP. Phosphocreatine has now turned back to creatine

2. Anaerobic Glycolysis Cytosol Mitochondrion Glucose Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

Glycolysis Pg 129 Glycolysis 1 Glucose Glycolysis High energy electrons (e–) 1 The 6-carbon sugar glucose is broken down into two 3-carbon pyruvic acid molecules with a net gain of 2 ATP and the release of high energy electrons. Glycolysis 2 ATP Cytosol Pyruvic acid Mitochondrion Pg 129 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

2 2 ATP’s in 4 ATP’s out Net Yield 2 ATP’s

Pg 129 Aerobic Respiration Citric Acid Cycle Cytosol 2 Glucose High energy electrons (e–) Glycolysis 2 ATP Cytosol Pyruvic acid Citric Acid Cycle 2 The 3-carbon pyruvic acids generated by glycolysis enter the mitochondria. Each loses a carbon (generating CO2) and is combined with a coenzyme to form a 2-carbon acetyl Coenzyme A (acetyl CoA). More high energy electrons are released. High energy electrons (e–) CO2 Acetyl CoA Mitochondrion Pg 129 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

Glycolysis Slide number: 5 Citric Acid Cycle Cytosol 2 Glucose High energy electrons (e–) Glycolysis 2 ATP Cytosol Pyruvic acid Citric Acid Cycle 2 The 3-carbon pyruvic acids generated by glycolysis enter the mitochondria. Each loses a carbon (generating CO2) and is combined with a coenzyme to form a 2-carbon acetyl Coenzyme A (acetyl CoA). More high energy electrons are released. High energy electrons (e–) CO2 Acetyl CoA 3 Each acetyl CoA combines with a 4-carbon oxaloacetic acid to form the 6-carbon citric acid, for which the cycle is named. For each citric acid a series of reactions removes 2 carbons (generating 2 CO2’s), synthesizes 1 ATP and releases more high energy electrons. The figure shows 2 ATP, resulting directly from 2 turns of the cycle per glucose molecule that enters glycolysis. Citric acid Mitochondrion Oxaloacetic acid Citric acid cycle High energy electrons (e–) 2 CO2 2 ATP Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

Glycolysis Slide number: 6 Electron Transport Chain Cytosol Glucose High energy electrons (e–) Glycolysis 2 ATP Cytosol Pyruvic acid High energy electrons (e–) CO2 Acetyl CoA Citric acid Mitochondrion Oxaloacetic acid Citric acid cycle High energy electrons (e–) 2 CO2 Electron Transport Chain The high energy electrons still contain most of the chemical energy of the original glucose molecule. Special carrier molecules bring the high energy electrons to a series of enzymes that convert much of the remaining energy to more ATP molecules. The other products are heat and water. The requirement of oxygen in this last step is why the overall process is called aerobic respiration. 2 ATP 4 Electron transport chain 32–34 ATP 2e– and 2H+ 1/2 O2 H2O2 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

Glycolysis Slide number: 1 Glycolysis Citric Acid Cycle Glucose Glycolysis High energy electrons (e–) 1 The 6-carbon sugar glucose is broken down into two 3-carbon pyruvic acid molecules with a net gain of 2 ATP and the release of high energy electrons. Glycolysis 2 ATP Cytosol Pyruvic acid Citric Acid Cycle 2 The 3-carbon pyruvic acids generated by glycolysis enter the mitochondria. Each loses a carbon (generating CO2) and is combined with a coenzyme to form a 2-carbon acetyl Coenzyme A (acetyl CoA). More high energy electrons are released. High energy electrons (e–) CO2 Acetyl CoA 3 Each acetyl CoA combines with a 4-carbon oxaloacetic acid to form the 6-carbon citric acid, for which the cycle is named. For each citric acid a series of reactions removes 2 carbons (generating 2 CO2’s), synthesizes 1 ATP and releases more high energy electrons. The figure shows 2 ATP, resulting directly from 2 turns of the cycle per glucose molecule that enters glycolysis. Citric acid Mitochondrion Oxaloacetic acid Citric acid cycle High energy electrons (e–) 2 CO2 2 ATP Electron Transport Chain 4 The high energy electrons still contain most of the chemical energy of the original glucose molecule. Special carrier molecules bring the high energy electrons to a series of enzymes that convert much of the remaining energy to more ATP molecules. The other products are heat and water. The requirement of oxygen in this last step is why the overall process is called aerobic respiration. Electron transport chain 32–34 ATP 2e– and 2H+ 1/2 O2 H2O2 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

3.

Electron Transport Chain

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