Presentation on theme: "Chapter 23 Metabolic Pathways for Carbohydrates"— Presentation transcript:
1 Chapter 23 Metabolic Pathways for Carbohydrates 23.1 Metabolism and Cell Structure23.2 ATP and Energy23.3 Important Coenzymes inMetabolic Pathways
2 Metabolism 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.
3 Stages of Metabolism Catabolic reactions are organized as stages: In Stage 1, digestion breaks down large molecules into smaller ones that enter the bloodstream.In Stage 2, molecules in the cells are broken down to two- and three-carbon compounds.In Stage 3, compounds are oxidized in the citric acid cycle to provide energy.
10 ATP and Muscle Contraction Muscle fibers contains filaments of actin and myosin.When a nerve impulse increases Ca2+, the filaments slide closer together to contract muscle.The hydrolysis of ATP in muscle provides the energy for contraction.As Ca2+ and ATP decrease, the filaments return to the relaxed position.
12 Coenzyme NAD+In cells, the oxidation of compounds provides 2H as 2H+ and 2e- that reduce coenzymes.NAD+ (nicotinamide adenine dinucleotide) participates in reactions that produce a carbon-oxygen double bond (C=O).Oxidation O||CH3—CH2—OH CH3—C—H + 2H+ + 2e-ReductionNAD H+ + 2e NADH + H+
13 Structure of Coenzyme NAD+ NAD+ (nicotinamide adenine dinucleotide) contains ADP, ribose, and nicotinamide.NAD+ reduces to NADH when the nicotinamide group accepts H+ and 2e-.
14 Coenzyme FADFAD participates in reactions that produce a carbon-carbon double bond (C=C).Oxidation—CH2—CH2— —CH=CH— + 2H+ + 2e-ReductionFAD + 2H+ + 2e FADH2
15 Structure of Coenzyme FAD FAD (flavin adenine dinucleotide) contains ADP and riboflavin (vitamin B2).FAD reduces to FADH2 when flavin accepts 2H+ and 2e-.
16 Coenzyme ACoA activates acyl groups such as the two-carbon acetyl group for transfer.O O|| ||CH3—C— + HS—CoA CH3—C—S—CoA