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MolBiol #3.2
 

MolBiol #3.2

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    MolBiol #3.2 MolBiol #3.2 Presentation Transcript

    • ЛЕКЦИЯ 3-2
      • Метаболизм
      • Metabolism: The sum of the chemical reactions in an organism
      • Catabolism: The energy-releasing processes
      • Anabolism: The energy-using processes
      Microbial Metabolism
    • Microbial Metabolism
      • Catabolism provides the building blocks and energy for anabolism.
      Figure 5.1
      • 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.
      PLAY Animation: Metabolic Pathways (Overview)
      • 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.
    • Enzymes Figure 5.2
    • Enzymes
      • Biological catalysts
        • Specific for a chemical reaction; not used up in that reaction
      • Apoenzyme: Protein
      • Cofactor: Nonprotein component
        • Coenzyme: Organic cofactor
      • Holoenzyme: Apoenzyme plus cofactor
    • Enzymes Figure 5.3
    • Important Coenzymes
      • NAD +
      • NADP +
      • FAD
      • Coenzyme A
    • Enzymes
      • The turnover number is generally 1-10,000 molecules per second.
      PLAY Animation: Enzyme–Substrate Interactions Figure 5.4
    • Enzyme Classification
      • Oxidoreductase: Oxidation-reduction reactions
      • Transferase: Transfer functional groups
      • Hydrolase: Hydrolysis
      • Lyase: Removal of atoms without hydrolysis
      • Isomerase: Rearrangement of atoms
      • Ligase: Joining of molecules, uses ATP
    • Factors Influencing Enzyme Activity
      • Enzymes can be denatured by temperature and pH
      Figure 5.6
    • Factors Influencing Enzyme Activity
      • Temperature
      Figure 5.5a
    • Factors Influencing Enzyme Activity
      • pH
      Figure 5.5b
    • Factors Influencing Enzyme Activity
      • Substrate concentration
      Figure 5.5c
    • Factors Influencing Enzyme Activity
      • Competitive inhibition
      Figure 5.7a–b
    • Factors Influencing Enzyme Activity
    • Factors Influencing Enzyme Activity
      • Noncompetitive inhibition
      Figure 5.7a, c
    • Factors Influencing Enzyme Activity
      • Feedback inhibition
      Figure 5.8
    • Ribozymes
      • RNA that cuts and splices RNA
    • 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
    • Oxidation-Reduction
      • In biological systems, the electrons are often associated with hydrogen atoms. Biological oxidations are often dehydrogenations.
      Figure 5.10
    • The Generation of ATP
      • ATP is generated by the phosphorylation of ADP.
    • The Generation of ATP
      • Substrate-level phosphorylation is the transfer of a high-energy PO 4 – to ADP.
    • 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.
    • 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.
    • Metabolic Pathways
    • Carbohydrate Catabolism
      • The breakdown of carbohydrates to release energy
        • Glycolysis
        • Krebs cycle
        • Electron transport chain
    • Glycolysis
      • The oxidation of glucose to pyruvic acid produces ATP and NADH.
      Figure 5.11, step 1
    • Preparatory Stage
      • Two ATPs are used
      • Glucose is split to form two Glucose-3-phosphate
      1 3 4 5 Figure 5.12, step 1
    • Energy-Conserving Stage
      • Two Glucose-3-phosphate oxidized to two Pyruvic acid
      • Four ATP produced
      • Two NADH produced
      9 Figure 5.12, step 2
    • Glycolysis
      • Glucose + 2 ATP + 2 ADP + 2 PO 4 – + 2 NAD +  2 pyruvic acid + 4 ATP + 2 NADH + 2H +
      PLAY Animation: Glycolysis
    • 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
    • Cellular Respiration
      • Oxidation of molecules liberates electrons for an electron transport chain.
      • ATP is generated by oxidative phosphorylation.
    • Intermediate Step
      • Pyruvic acid (from glycolysis) is oxidized and decarboyxlated.
      Figure 5.13 (1 of 2)
    • Krebs Cycle
      • Oxidation of acetyl CoA produces NADH and FADH 2 .
      PLAY Animation: Krebs Cycle
    • Krebs Cycle Figure 5.13 (2 of 2)
    • The Electron Transport Chain
      • A series of carrier molecules that are, in turn, oxidized and reduced as electrons are passed down the chain.
      • Energy released can be used to produce ATP by chemiosmosis.
      PLAY Animation: Electron Transport Chains and Chemiosmosis
    • Figure 5.11
    • Chemiosmosis Figure 5.16
    • Chemiosmosis Figure 5.15
    • Respiration
      • Aerobic respiration: The final electron acceptor in the electron transport chain is molecular oxygen (O 2 ).
      • Anaerobic respiration: The final electron acceptor in the electron transport chain is not O 2 . Yields less energy than aerobic respiration because only part of the Krebs cycles operations under anaerobic conditions.
    • Anaerobic Respiration CH 4 + H 2 O CO 3 2 – H 2 S + H 2 O SO 4 – NO 2 – , N 2 + H 2 O NO 3 – Products Electron acceptor
    • Plasma membrane Mitochondrial inner membrane ETC Cytoplasm Cytoplasm Cytoplasm Prokaryote Mitochondrial matrix Krebs cycle Cytoplasm Intermediate step Cytoplasm Glycolysis Eukaryote Pathway
      • Energy produced from complete oxidation of one glucose using aerobic respiration.
      2 2 0 FADH 2 produced 10 4 Total 6 2 2 NADH produced 2 Krebs cycle 0 Intermediate step 2 Glycolysis ATP produced Pathway
      • ATP produced from complete oxidation of one glucose using aerobic respiration.
      • 36 ATPs are produced in eukaryotes.
      4 30 4 Total 4 0 From FADH 18 2 Krebs cycle 6 6 From NADH By oxidative phosphorylation 0 Intermediate step 2 Glycolysis By substrate-level phosphorylation Pathway