LEC 5 Metabolism Thermodynamics First Law of Thermodynamics

LEC 5

Metabolism Thermodynamics First Law of Thermodynamics Energy can be transferred and transformed, but it cannot be created or destroyed Second Law of Thermodynamics Every energy transfer or transformation increases the entropy of the Universe Entropy (S) A measure of disorder, or randomness

Metabolism Metabolic pathways Catabolic pathways – release energy by breaking down complex molecules to simpler compounds Anabolic pathways – consume energy to build complicated molecules form simpler ones The main metabolic pathways of the Golgi Apparatus would be considered which type of pathway? Ribosomes? Lysosome?

The main metabolic pathways of the Golgi Apparatus would be considered which type of pathway? Ribosomes? - Anabolic pathways * building proteins and macromolecules Lysosome? - Catabolic pathways *intercellular digestion to produce sugars, amino acids, and other monomers

Core Question 1. An enzyme is made up of two subunits (separate polypeptide chains). A. What level of structure defines the overall structure of the functional protein? B. You find that this enzyme requires vitamin D to function optimally. What role is vitamin D playing? What is meant by an allosteric site? C. Name three ways that you can diminish the activity of this enzyme.

A. What level of structure defines the overall structure of the functional protein? The specificity of an enzyme results from its shape, which is a consequence of its amino acid sequence.

B. You find that this enzyme requires vitamin D to function optimally. What role is vitamin D playing? What is meant by an allosteric site? Cofactor and Coenzyme Cofactor – nonprotein helpers for catalytic activity Bound to enzyme as a permanent residents Coenzyme – if cofactor is organic Most vitamins act as coenzymes or raw materials from which coenzymes are made Allosteric Site – A site on a multi-subunit enzyme that is not the substrate binding site but that when reversibly bound by and effector induces a conformational change in the enzyme altering its catalytic properties

C. Name three ways that you can diminish the activity of this enzyme. Temperature Increase Temp and the rate of the enzymatic reaction increases, up to a point • p. H Ionic Strength Chemicals that specifically influence the enzyme

A. What does the term Energy of Activation mean? B. William Gibbs defined a useful function called Gibbs free energy. What is the change in free energy equation AND define each term If a reaction is spontaneous what will be the value of Free energy?

What does the term Energy of Activation mean? The activation energy of a reaction is the amount of energy needed to start the reaction. It represents the minimum energy needed to form an activated complex during a collision between reactants.

What is the change in free energy equation AND define each term If a reaction is spontaneous what will be the value of Free energy? ΔG = ΔH – TΔS ΔG = The change in free energy ΔH = The change in the system’s enthalpy ΔS = The change in the systems entropy T = the absolute temperature in Kelvin (K) If the reaction is spontaneous then ΔG will be negative

Exergonic and Endergonic Reactions in Metabolism Exergonic reaction – “energy outward” proceeds with a net release of free energy and is spontaneous Endergonic reaction – “energy inward” absorbs free energy from its surroundings and is nonspontaneous

LE 8 -6 A Free energy Reactants Amount of energy released ( G < 0) Energy Products Progress of the reaction Exergonic reaction: energy released

LE 8 -6 B Free energy Products Energy Reactants Progress of the reaction Endergonic reaction: energy required Amount of energy required ( G > 0)

Energonic or Exergonic? Protein synthesis Cellular Respiration Na+/K+ pump Match burning an ice cube

Core Question A. What is the name of this reaction? B. What type of Metabolic pathway would this reaction be? (Anabolic/Catbolic) C. Where might this type of reaction occur within a cell? D. Exergonic or Endergonic? E. What are the correct thermodynamic properties for a chemical reaction in which amino acids are linked to form a protein?

A. What is the name of this reaction? Dehydration Reaction B. What type of Metabolic pathway would this reaction be? Anabolic pathway C. Where might this type of reaction occur within a cell? In the Ribosomes In the cytosol (free ribosomes) On the outside of the endoplasmic reticulum (ER) or the nuclear envelope (Bound ribosomes) D. Exergoinic or Endergonic? Endergonic need to put energy into it

What are the correct thermodynamic properties for a chemical reaction in which amino acids are linked to form a protein? It is becoming more ordered so Entropy will decrease = - ∆S • ∆S < 0, decrease of entropy, increase in order It is an Anabolic pathway so energy is consumed, added, so ∆H would be positive = +∆H Because energy is added this is considered a Endergonic reaction and thus the free energy will increase = + ∆G

LE 8 -6 B Free energy Products Energy Reactants Progress of the reaction Endergonic reaction: energy required Amount of energy required ( G > 0)