Chapter 22 Metabolic Pathways Lecture Presentation Chapter 22 Metabolic Pathways for Carbohydrates Karen C. Timberlake

Chapter 22 Metabolic Pathways for Carbohydrates The clinical lipid specialist provides care for patients with liver-related conditions. Nursing care involves diagnosing illnesses, ordering and analyzing laboratory tests, developing appropriate treatment plans, providing patient education, and giving instruction in preventative care.

Chapter Readiness Core Chemistry Skills Identifying D- and L-Fischer Projections (15.2) Describing Enzyme Action (20.1) Classifying Enzymes (20.2) Identifying Factors Affecting Enzyme Activity (20.3) Describing the Role of Cofactors (20.6)

Chapter Readiness Metabolism involves catabolic reactions that break down large, complex molecules to provide energy and smaller molecules. anabolic reactions that use ATP energy to build larger molecules. Learning Goal Describe the three stages of catabolism, the structure of ATP, and the role of ATP.

Stages of Catabolism Catabolic reactions are organized in stages as shown below. Stage 1: Digestion and hydrolysis break down large molecules to smaller ones that enter the bloodstream. Stage 2: Within the cells, degradation breaks down molecules to two- and three-carbon compounds. Stage 3: Oxidation of small molecules in the citric acid cycle and electron transport provides ATP energy.

Stages of Catabolism In the three stages of catabolism, large molecules from foods are digested and degraded to provide smaller molecules that can be oxidized to produce energy.

Cell Structure for Metabolism Cells in plants and animals are known as eukaryotic cells, which have a nucleus that contains DNA. In animals, a cell membrane separates the materials inside the cell from the aqueous environment surrounding the cell. the cell nucleus contains the genes that control DNA replication and protein synthesis. the cytosol, or fluid part of the cell, contains electrolytes and enzymes that catalyze chemical reactions in the cell.

Cell Structure Metabolic reactions occur at specific sites within cells.

Cell Components and Function

ATP, Adenosine Triphosphate The ATP molecule, composed of the base adenine, a ribose sugar, and three phosphate groups, hydrolyzes to form ADP and AMP along with a release of energy.

Hydrolysis of ATP Yields Energy The hydrolysis of ATP to ADP releases 7.3 kcal (31 kJ) per mole. ATP  ADP + Pi + 7.3 kcal/mole The hydrolysis of ADP to AMP releases 7.3 kcal (31 kJ) per mole. ADP  AMP + Pi + 7.3 kcal/mole

ATP Drives Reactions When ATP hydrolyzes, the energy released can be used to drive an energy-requiring reaction.

Chemistry Link to Health: ATP, Ca2+ in Muscle Contraction Muscle fibers consist of protein fibers containing two kinds of proteins, actin and myosin. contract when a nerve impulse increases Ca2+ concentration. obtain energy for contraction from the hydrolysis of ATP. return to the relaxed position as Ca2+ and ATP decrease.

Chemistry Link to Health: ATP, Ca2+ in Muscle Contraction Muscle contraction continues as long as both ATP and Ca2+ levels are high around the filaments. When the nerve impulse ends, the calcium channels close. Ca2+ concentration decreases as energy from ATP pumps the remaining Ca2+ out of the filaments and back across the membrane, causing the muscle to relax.

Study Check Match the following: 1) ATP 2) ADP + Pi A. used in anabolic reactions B. the energy-storage molecule C. combined with energy-requiring reactions D. hydrolysis products

Solution Match the following: 1) ATP 2) ADP + Pi A. used in anabolic reactions 1) ATP B. the energy-storage molecule 1) ATP C. combined with energy-requiring reactions 1) ATP D. hydrolysis products 2) ADP + Pi