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Ch.6: Introduction to Metabolism. Metabolism, Transformation of energy, ATP laws of thermo-dynamics Enzymes, Controls of metabolism. YIKES!!! Metabolic pathways. What is Metabolism? Put the following words into one of these two categories:. Anabolic Catabolic

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Ch 6 introduction to metabolism l.jpg

Ch.6: Introduction to Metabolism

Metabolism, Transformation of energy, ATPlaws of thermo-dynamics

Enzymes, Controls of metabolism


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YIKES!!!Metabolicpathways


What is metabolism put the following words into one of these two categories l.jpg
What is Metabolism?Put the following words into one of these two categories:

AnabolicCatabolic

exergonic, endergonic, nonspontaneous, spontaneous,

-ΔG, +ΔG, uphill, downhill, respiration, photosynthesis

ATP ADP + Pi, ADP + Pi  ATP

loss of free energy (G), gain of free energy (G)

products have greater G than reactants, reactants have greater G than products

absorbs free energy from surroundings, releases free energy to surroundings

hydrolysis, condensation/dehydration

ΔG= -686 kcal/mol, ΔG= 686 kcal/mol

C6H12O6 + O2  H20 + CO2, H20 + CO2  C6H12O6 + O2


What is metabolism put the following words into one of these two categories4 l.jpg
What is Metabolism?Put the following words into one of these two categories:

AnabolicCatabolic

exergonic, endergonic, nonspontaneous, spontaneous,

-ΔG, +ΔG, uphill, downhill, respiration, photosynthesis

ATP ADP + Pi, ADP + Pi  ATP

loss of free energy (G), gain of free energy (G)

products have greater G than reactants, reactants have greater G than products

absorbs free energy from surroundings, releases free energy to surroundings

hydrolysis, condensation/dehydration

ΔG= -686 kcal/mol, ΔG= 686 kcal/mol

C6H12O6 + O2  H20 + CO2, H20 + CO2  C6H12O6 + O2


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ATP’s Structure

It is a Nucleotide:Base Sugar Phosphates

Hydrolysis of ATP into ADP



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Energy Coupling:

The use of an exergonic process to drive an endergonic reaction.

  • Ex: Adding a phosphate group (Pi) to molecules makes them unstable and usually highly reactive

  • Where does that Pi come from?


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Example coupling reaction

  • ATP’sphosphatemakes GLU more reactive, this is phosphorylation/ energy coupling

Note: what is the second law of thermodynamics?

Exergonic


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What about this example?

A + B  AB ΔG = 9.0 kcal/mol

ATP+ H2O ADP+Pi ΔG = -7.3 kcal/mol


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Closed system

Using energy gradients (energy at each step) to help do work. Staying away from equilibrium. (like respiration!) how is a human an open system?

Open system



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Enzymes

  • Examples: hexokinase, sucrase, catalase, pepsin, trypsin---all are specific

  • Substrate(s) enzyme Product(s)

    The action can be catabolic or anabolic.

    “Induced fit” not rigid—like a hand shake

  • http://scholar.hw.ac.uk/site/biology/activity7.asp?outline=no


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Negative G= a loss of free Energy

The products have less energy than the reactants, EXERGONIC


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Enzyme rate and rate of reaction

  • How does the amount of enzyme affect the rate of the reaction?

  • How does the amount of enzyme affect the rate of an enzyme?

  • How does the amount of substrate affect the rate of the reaction?

  • How does the amount of substrate affect the rate of the enzyme?

  • What are the differences between competitive and noncompetitive inhibitors.

  • What is cooperativity? How might this be involved with negative feedback?


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Free Energy and Metabolism:

  • C6H12O6 + 6O2 6CO2 + 6H2O

  • G = - 686 kcal/mol (-2870 kJ/mol)

    • Is this Exergonic or Endergonic?• What is this reaction?

  • 6CO2 + 6H2O C6H12O6 + 6O2

  • G = +686 kcal/mol (+2870 kJ/mol)

  • This reaction is photosynthesis.

  • Where is the Energy coming from to drive this nonspontaneous reaction?


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Energy transformations

  • 1. First law of thermodynamics:Conservation of energy—it is not lost or destroyed. There is a constant amount in the universe. (what form has the lowest Energy?)

  • 2. Second law of thermodynamics: Entropy(S), every energy transfer increases entropy of the universe.


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G(free energy)=H(total Energy) –TS

This change in Energy can be harnessed to do work! Kinetic (KE) and Potential energy (PE)




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Toothpickase Demonstration

  • How many subunits does the enzyme have? __

  • What is the quaternary structure for your enzyme? ____________

  • Where is your active site? ______________

  • What are the products of the reaction of toothpickase with its substrate? __________

  • Is the enzyme changed in any way throughout the reaction? ________



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  • ENZYMES: conditionspH and temperature sensitive

  • Most will DENATURE when out of range


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  • Competitive conditionsinhibitor

  • Competes forthe active site

  • Non-competitive inhibitor

  • Doesn’t compete with the active site


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Allosteric enzymes: conditions Activators and Inhibitors (active forms, inactive forms)


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Fig 6.16 conditions

  • Feedback inhibition

  • Pathwaysswitching off because of an end product acting as an allosteric inhibitor


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Allosteric again conditions

  • Cooperativity: the substrate itself “turns the enzyme on” / activates it