Microbiology AN INTRODUCTION

Transcription

1 TORTORA FUNKE CASE Microbiology AN INTRODUCTION EIGHTH EDITION B.E Pruitt & Jane J. Stein Chapter 5, part A Microbial Metabolism PowerPoint Lecture Slide Presentation prepared by Christine L. Case

2 Microbial Metabolism Metabolism is the sum of the chemical reactions in an organism. Catabolism is the energy-releasing processes. Anabolism is the energy-using processes.

3 Microbial Metabolism Catabolism provides the building blocks and energy for anabolism. Figure 5.1

4 A metabolic pathway is a sequence of enzymatically catalyzed chemical reactions in a cell. Metabolic pathways are determined by enzymes. Enzymes are encoded by genes.

5 The collision theory states that chemical reactions can occur when atoms, ions, and molecules collide. Activation energy is needed to disrupt electronic configurations. Reaction rate is the frequency of collisions with enough energy to bring about a reaction. Reaction rate can be increased by enzymes or by increasing temperature or pressure.

6 Enzymes Figure 5.2

7 Enzymes Biological catalysts Specific for a chemical reaction; not used up in that reaction Apoenzyme: protein Cofactor: Nonprotein component Coenzyme: Organic cofactor Holoenzyme: Apoenzyme + cofactor

8 Enzymes Figure 5.3

9 Important Coenzymes NAD + NADP + FAD Coenzyme A

10 Enzymes The turnover number is generally 1-10,000 molecules per second. Figure 5.4

11 Enzyme Classification Oxidoreductase Transferase Hydrolase Lyase Isomerase Ligase Oxidation-reduction reactions Transfer functional groups Hydrolysis Removal of atoms without hydrolysis Rearrangement of atoms Joining of molecules, uses ATP

12 Factors Influencing Enzyme Activity Enzymes can be denatured by temperature and ph Figure 5.6

13 Factors Influencing Enzyme Activity Temperature Figure 5.5a

14 Factors Influencing Enzyme Activity ph Figure 5.5b

15 Factors Influencing Enzyme Activity Substrate concentration Figure 5.5c

16 Factors Influencing Enzyme Activity Competitive inhibition Figure 5.7a, b

17 Factors Influencing Enzyme Activity

18 Factors Influencing Enzyme Activity Noncompetitive inhibition Figure 5.7a, c

19 Factors Influencing Enzyme Activity Feedback inhibition Figure 5.8

20 Ribozymes RNA that cuts and splices RNA

21 Oxidation-Reduction Oxidation is the removal of electrons. Reduction is the gain of electrons. Redox reaction is an oxidation reaction paired with a reduction reaction. Figure 5.9

22 Oxidation-Reduction In biological systems, the electrons are often associated with hydrogen atoms. Biological oxidations are often dehydrogenations. Figure 5.10

23 The Generation of ATP ATP is generated by the phosphorylation of ADP.

24 The Generation of ATP Substrate-level phosphorylation is the transfer of a high-energy PO 4 - to ADP.

25 The Generation of ATP Energy released from the transfer of electrons (oxidation) of one compound to another (reduction) is used to generate ATP by chemiosmosis.

26 The Generation of ATP Light causes chlorophyll to give up electrons. Energy released from the transfer of electrons (oxidation) of chlorophyll through a system of carrier molecules is used to generate ATP.

27 Metabolic Pathways

28 Carbohydrate Catabolism The breakdown of carbohydrates to release energy Glycolysis Krebs cycle Electron transport chain

29 Glycolysis The oxidation of glucose to pyruvic acid, produces ATP and NADH.

30 Preparatory Stage Preparatory Stage Glucose 1 2 ATPs are used Glucose is split to form 2 Glucose-3- phosphate Glucose 6-phosphate Fructose 6-phosphate Fructose 1,6-diphosphate 5 Dihydroxyacetone phosphate (DHAP) Glyceraldehyde 3-phosphate (GP) Figure

31 Energy-Conserving Stage 6 1,3-diphosphoglyceric acid 2 Glucose-3- phosphate oxidized to 2 Pyruvic acid 4 ATP produced 2 NADH produced phosphoglyceric acid 2-phosphoglyceric acid Phosphoenolpyruvic acid (PEP) 10 Pyruvic acid Figure

32 Glycolysis Glucose + 2 ATP + 2 ADP + 2 PO NAD + 2 pyruvic acid + 4 ATP + 2 NADH + 2H +

33 Alternatives to Glycolysis Pentose phosphate pathway: Uses pentoses and NADPH Operates with glycolysis Entner-Doudoroff pathway: Produces NADPH and ATP Does not involve glycolysis Pseudomonas, Rhizobium, Agrobacterium