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. Formation of ATP from Carbs, Proteins and Fat
Enzymes of metabolic pathways are able to capture the energy contained in carbohydrates, proteins and fatty acids in small portions and store it in form of internal high energy compounds such as ATP, drastically reducing the amount of energy lost as heat.

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

10. Adenosine Triphosphate (ATP)
Figure 2.22

11. How ATP Drives Cellular Work
Figure 2.23

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

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

14. Structural Levels of Proteins
Figure 2.17a-c

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

18. Structural Levels of Proteins
Figure 2.17d, e

19. 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

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

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

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

23. 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

24. Characteristics of Enzymes
Figure 2.19

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

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

27. Enzymes speed biochemical reactions
Lower activation E
Specific
May require Cofactors or Coenzymes
Modulators
Acidity
Temperature
Competitive inhibitors
Allosteric
Concentrations

28. Cofactors and Enzyme Activity
Cofactors are inorganic substrates. Some cofactors are required to produce a chemical reaction between the enzyme and the substrate, while others merely increase the rate of catalysis. Cofactors are sometimes attach to the enzyme, much like a prosthetic limb. Others are loosely bound to the enzyme.

29. Coenzymes and Enzyme Activity
Unlike the inorganic cofactors, coenzymes are organic molecules. Certain enzymes need coenzymes to bind to the substrate and cause a reaction. Since the coenzymes are changed by the chemical reaction, these are considered to be secondary substrates of the reaction. Though enzymes are specific to the substrate, coenzymes are not specific to the enzymes they assist. Some chemical reactions within the cells of the body do require a cofactor or a coenzyme to work properly, while others do not. The body is unable to manufacture these products, so the way to get the vitamins necessary to produce cofactors and coenzymes is to eat a healthy, balanced diet full of all the vitamins necessary for bodily functions.

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

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

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

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

34. 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

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

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

40. 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

41. Figure 4-23: Pyruvate metabolism

42. 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

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

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

46. Protein Catabolism
Deaminated
Conversion
Glucose
Acetyl CoA

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

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

55. 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.

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

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

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

59. 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