Download 25-01_pptlect

Anatomy & Physiology
SIXTH EDITION
Chapter 25, part 1
Metabolism and Energetics
PowerPoint® Lecture Slide Presentation prepared by
Dr. Kathleen A. Ireland, Biology Instructor, Seabury Hall, Maui, Hawaii
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings
Frederic H. Martini
Fundamentals of
Learning Objectives
• Explain why cells need to synthesis new organic
components
• Describe the basic steps in glycolysis, the TCA
cycle, and the electron transport chain
• Summarize the energy yield of glycolysis and
cellular respiration
• Describe the pathways involved in lipid, protein
and nucleic acid metabolism
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings
Learning Objectives
• Summarize the characteristics of the absorptive
and postabsorptive metabolic states
• Explain what constitutes a balanced diet and why
such a diet is important
• Define metabolic rate and discuss the factors
involved in determining an individual’s BMR
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings
SECTION 25-1
An Overview of Metabolism
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings
Metabolism
• Metabolism is all the chemical reactions that
occur in an organism
• Cellular metabolism
• Cells break down excess carbohydrates first,
then lipids
• Cells conserve amino acids
• 40% of the energy released in catabolism is
captured in ATP
• Rest is released as heat
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings
Figure 25.1 An Introduction to Cellular
Metabolism
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings
Figure 25.1
Anabolism
• Performance of structural maintenance and
repairs
• Support of growth
• Production of secretions
• Building of nutrient reserves
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings
Figure 25.2 Metabolic Turnover and Cellular
ATP Production
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings
Figure 25.2
Cells and Mitochondria
• cells provide small organic molecules for their
mitochondria
• Mitochondria produce ATP used to perform
cellular functions
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings
Figure 25.3 Nutrient Use in Cellular Metabolism
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings
Figure 25.3
SECTION 25-2
Carbohydrate Metabolism
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings
Most cells generate ATP through the breakdown
of carbohydrates
• Glycolysis
• One molecule of glucose = two pyruvate ions,
two ATP, two NADH
• Aerobic metabolism (cellular respiration)
• Two pyruvates = 34 ATP
• The chemical formula for this process is
C6H12O6 + 6 O2  6 CO2 + 6 H2O
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings
Glycolysis
• The breakdown of glucose to pyruvic acid
• This process requires:
• Glucose molecules
• Cytoplasmic enzymes
• ATP and ADP
• Inorganic phosphate
• NAD (nicotinamide adenine dinucleotide)
• The overall reaction is:
Glucose + 2 NAD + 2 ADP + 2Pi 
2 Pyruvic acid + 2 NADH + 2 ATP
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings
Figure 25.4 Glycolysis
PLAY
Animation: Steps in Glycolysis
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings
Figure 25.4
Figure 25.4 Glycolysis
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings
Figure 25.4
Mitochondrial ATP Production
(cellular respiration)
• Pyruvic acid molecules enter mitochondria
• Broken down completely in TCA cycle
• Decarboxylation
• Hydrogen atoms passed to coenzymes
• Oxidative phosphorylation
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings
Figure 25.5 The TCA Cycle
PLAY
Animation: TCA Cycle
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings
Figure 25.5
Figure 25.5 The TCA Cycle
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings
Figure 25.5a
Figure 25.5 The TCA Cycle
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings
Figure 25.5b
Oxidative phosphorylation and the ETS
• Requires coenzymes and consumes oxygen
• Key reactions take place in the electron transport
system (ETS)
• Cytochromes of the ETS pass electrons to
oxygen, forming water
• The basic chemical reaction is:
2 H2 + O2  2 H2O
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings
Figure 25.6 Oxidative Phosphorylation
PLAY
Animation: Chemiosmosis
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings
Figure 25.6
Figure 25.6 Oxidative Phosphorylation
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings
Figure 25.6a
Figure 25.6 Oxidative Phosphorylation
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings
Figure 25.6b
Energy yield of glycolysis and cellular respiration
• Per molecule of glucose entering these pathways
• Glycolysis – has a net yield of 2 ATP
• Electron transport system – yields
approximately 28 molecules of ATP
• TCA cycle – yields 2 molecules of ATP
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings
Figure 25.7 A Summary of the Energy Yield of
Aerobic Metabolism
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings
Figure 25.7
Synthesis of glucose and glycogen
• Gluconeogenesis
• Synthesis of glucose from noncarbohydrate
precursors
• Lactic acid, glycerol, amino acids
• Liver cells synthesis glucose when
carbohydrates are depleted
• Glycogenesis
• Formation of glycogen
• Glucose stored in liver and skeletal
muscle as glycogen
• Important energy reserve
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings
Figure 25.8 Carbohydrate Breakdown and
Synthesis
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings
Figure 25.8