1. Chapter 4
Cellular Metabolism

2. About this Chapter Energy for synthesis and movement
Energy transformation
Enzymes and how they speed reactions
Metabolic pathways
ATP its formation and uses in metabolism
Synthesis of biologically important molecules

3. Energy (E) Transfer Overview
Energy does work
Kinetic energy
Potential energy
Energy conversion

4. Energy (E) Transfer Overview
Figure 4-1: Energy transfer in the environment

6. Chemosynthesis versus Photosynthesis
6CO2 + 6H2S → C6H12O6 + 6S
Needs heat added such as from hydrothermal vents in the deep ocean
Photosynthesis
2n CO2 + 2n H2O + photons → 2(CH2O)n + 2n O2
Occurs in Two Stages
Stage 1: Light energy used to form ATP and NADPH
Stage 2: Uses ATP and NADPH to reduce CO2

7. Energy and Chemical Reactions
Figure 4-5: Energy transfer and storage in biological reactions

8. Adenosine Triphosphate (ATP)
Source of immediately usable energy for the cell
Adenine-containing RNA nucleotide with three phosphate groups

9. Adenosine Triphosphate (ATP)
Figure 2.22

10. How ATP Drives Cellular Work
Figure 2.23

11. Protein
Macromolecules composed of combinations of 20 types of amino acids bound together with peptide bonds
Figure 2.16

12. Structural Levels of Proteins
Primary – amino acid sequence
Secondary – alpha helices or beta pleated sheets

13. Structural Levels of Proteins
Figure 2.17a-c

14. Structural Levels of Proteins
Tertiary – superimposed folding of secondary structures
Quaternary – polypeptide chains linked together in a specific manner

15. Structural Levels of Proteins
Figure 2.17d, e

16. Fibrous and Globular Proteins
Fibrous proteins
Extended and strandlike proteins
Examples: keratin, elastin, collagen, and certain contractile fibers
Globular proteins
Compact, spherical proteins with tertiary and quaternary structures
Examples: antibodies, hormones, and enzymes

17. Protein Synthesis
Figure 4-34: Summary of transcription and translation

18. Post – Translational protein modificaiton
Figure 4-35: Post-translational modification and the secretory pathway

19. Post – Translational protein modificaiton
Folding, cleavage, additions: glyco- lipo- proteins

20. Characteristics of Enzymes
Most are globular proteins that act as biological catalysts
Holoenzymes consist of an apoenzyme (protein) and a cofactor (usually an ion)
Enzymes are chemically specific
Frequently named for the type of reaction they catalyze
Enzyme names usually end in -ase
Lower activation energy

21. Characteristics of Enzymes
Figure 2.19

22. Enzymes speed biochemical reactions
Figure 4-8: Two models of enzyme binding sites

23. Mechanism of Enzyme Action
Enzyme binds with substrate
Product is formed at a lower activation energy
Product is released

24. Enzymes speed biochemical reactions
Lower activation E
Specific
Cofactors
Modulators
Acidity
Temperature
Competitive inhibitors
Allosteric
Concentrations

25. Protein Denaturation
Reversible unfolding of proteins due to drops in pH and/or increased temperature
Figure 2.18a

26. Protein Denaturation
Irreversibly denatured proteins cannot refold and are formed by extreme pH or temperature changes
Figure 2.18b

27. Law of Mass Action Defined: Equlibrium Reversible
Figure 4-17: Law of mass action

28. Types of Enzymatic Reactions
Oxidation–reduction
Hydrolysis–dehydration
Addition–subtraction exchange
Ligation

29. Figure 4-18b: A group of metabolic pathways resembles a road map
Cell Metabolism
Pathways
Intermediates
Catabolic - energy
Anabolic - synthesis
Figure 4-18b: A group of metabolic pathways resembles a road map

30. Control of Metabolic Pathways
Feedback inhibition
Figure 4-19: Feedback inhibition

32. ATP Production Glycolysis Pyruvate Anaerobic respiration
Lactate production
2 ATPs produced
Figure 4-21: Overview of aerobic pathways for ATP Production

34. Pyruvate Metabolism Aerobic respiration In mitochondria
Acetyl CoA and CO2
Citric Acid Cycle or Kreb’s Cycle or TCA Cycle
Energy Produced from 1 Acetyl CoA
1 ATP
3 NADH
1 FADH2
Waste–2 CO2s

35. Figure 4-23: Pyruvate metabolism

36. Electron Transport High energy electrons Energy transfer
ATP synthesized from ADP
H2O is a byproduct- In a typical individual this amounts to approximately 400 ml/day

38. Electron Transport
Figure 4-25: The electron transport system and ATP synthesis

41. Biomolecules Catabolized to make ATP
Complex Carbohydrates
Glycogen catabolism
Liver storage
Muscle storage
Glucose produced
Figure 4-26: Glycogen catabolism

42. Protein Catabolism
Deaminated
Conversion
Glucose
Acetyl CoA

43. Protein Catabolism
Figure 4-27: Protein catabolism and deamination

46. Lipid Catabolism Higher energy content Triglycerides to glycerol
Fatty acids
Ketone bodies - liver

47. Fat mass, adipose tissue and energy stores
Liver triglycerides = 450 kcal
Muscle triglycerides = 3000 kcal
Liver glycogen = 400 kcal
Muscle glycogen = 2500 kcal
Adipose tissue triglycerides = 120,000 kcal
Data for a 70 kg lean subject.

48. Synthetic (Anabolic) pathways
Glycogen synthesis
Liver storage
Glucose to glycogen
Gluconeogenesis
Amino acids
Glycerol
Lactate
Figure 4-29: Gluconeogenesis

49. Figure 4-30: Lipid synthesis
Lipogenesis
Acetyl Co A
Glycerol
Fatty acids
Triglycerides
Figure 4-30: Lipid synthesis

50. Figure 4-30: Lipid synthesis
Lipogenesis
Figure 4-30: Lipid synthesis

51. Summary Energy: chemical, transport, mechanical work
Reactions: reactants, activation energy, directions
Enzymes: characteristics, speed & control pathways
Metabolism: catabolic, anabolic
ATP production: anaerobic, aerobic, glycolysis,
citric acid cycle, & electron transport
Synthesis of carbohydrates, lipids and proteins