Chapter 6 Metabolism: Energy and Enzymes Read chapter 6 of textbook Read Enzyme Activity Lab in AP Lab Manual (#13) Read pages 22 (chemical reactions and metabolic processes) in CliffsAP (3rd) Do MC questions on pg 25-28 of Cliffs – Due Sept 17 Be sure you could answer the free response questions pg 29 Mills 2012

Chapter 6 Metabolism: Energy and Enzymes Topics 6.1 Cells and the Flow of Energy 6.2 Metabolic Reactions and Energy Transformations 6.3 Metabolic Pathways and Enzymes 6.4 Metabolic Pathways and Oxidation Reduction Mills 2012

Metabolism: Energy and Enzymes 6.1 Energy Energy = capacity to do work or bring about a change All living things need energy Many kinds of energy Kinetic energy Energy of motion Mechanical Potential energy Stored energy Chemical energy Mills 2012

Biology, 9th ed,Sylvia Mader Chapter 06 Flow of Energy Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. sun CO2 H2O solar energy producer carbohydrate heat solar energy heat heat heat heat Chemical energy Mechanical energy Metabolism

Metabolism: Energy and Enzymes 6.1 Energy Two laws of thermodynamics Law of conservation of energy Energy cannot be created or destroyed, only converted from one form to another Second law (Entropy) Energy cannot be converted from one form to another without a loss of usable energy Energy = Mass x The Velocity of Light squared Mills 2012

Metabolism: Energy and Enzymes 6.1 Energy Entropy A measure of randomness or disorder Things tend toward more entropy – takes energy to keep organized Mills 2012

Biology, 9th ed,Sylvia Mader Cells and Entropy Chapter 06 H2O C6H12O6 CO2 Glucose Carbon dioxide and water • more organized kinetic energy • less organized • more potential energy • less potential energy • less stable (entropy) • more stable (entropy) a. H+ H+ channel protein H+ H+ H+ H+ H+ H+ H+ H+ H+ H+ H+ H+ H+ H+ H+ H+ Unequal distribution of hydrogen ions Equal distribution of hydrogen ions • more organized • less organized • more potential energy • less potential energy • less stable (entropy) • more stable (entropy) b. Metabolism

Metabolism: Energy and Enzymes 6.1 Energy Whole ecosystem also follows these rules Ultimately all energy ends up as heat, which is very random energy (high entropy) Mills 2012

Metabolism: Energy and Enzymes 6 Metabolism: Energy and Enzymes 6.2 Metabolic Reactions and Energy Transformations Metabolism = sum of all reactions that go on in body Free energy = amount of energy (G) that is still available (free) to do work after a chemical reaction has occurred. (change in energy is designated delta G) If delta G is negative it means the products have less energy than the reactants did. And the reaction will occur spontaneously Exergonic – give off energy Delta G is negative ATP  ADP +P + free Energy Endergonic – need energy Delta G is positive – products have more free energy than reactants. Free Energy + Reactants  Products Mills 2012

Metabolism: Energy and Enzymes 6 Metabolism: Energy and Enzymes 6.2 Metabolic Reactions and Energy Transformations Coupled reactions Many reactions in body are coupled One gives off energy and the other uses it Mills 2012

Metabolism: Energy and Enzymes 6 Metabolism: Energy and Enzymes 6.2 Metabolic Reactions and Energy Transformations ATP; energy for Cells Adenosine triphosphate is a common source of stored energy for cells Provides energy for: Chemical work – synthesizing macromolecules Transport work – pumps substances across membranes Mechanical work – muscle contractions, cilia, flagella, cytoskeleton Energy stored in third phosphate bond ATP is a nucleotide Mills 2012

Coupled Reactions 12 Metabolism Biology, 9th ed,Sylvia Mader Chapter 06 Slide #12 Metabolism Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 1 Myosin assumes its resting shape when It combines with ATP. 2 ATP splits into ADP and p , causing myosin to change its shape and allowing it to attach to actin. 3 Release of ADP and p cause myosin to again change shape and pull against actin, generating force and motion. actin P myosin ATP ADP 12

Metabolism: Energy and Enzymes 6.3 Metabolic Pathways and Enzymes Series of consecutive reactions Each step catalyzed by an enzyme Enzymes (organic catalysts) are made of proteins Lower the activation energy Substance enzyme reacts with is called a substrate Mills 2012

Mills 2012

Metabolism: Energy and Enzymes 6.3 Metabolic Pathways and Enzymes Importance of Enzymes Enzymes are needed for most chemical reactions to occur in living cells, lower activation energy Such as getting “energy” from sugars We would die without enzymes Enzyme acts on a substrate Enzyme names often end in “ase” Enzymes are organic (usually globular proteins) catalysts Speed up a reaction without being used up themselves Can speed up a reaction by as much as a million times Starch degradation by enzyme amylase animation ..\..\Biology\Biology Clipart Movies Animations Sounds\Biology movies\starch degrade animation.dir Mills 2012

Metabolism: Energy and Enzymes 6.3 Metabolic Pathways and Enzymes How Enzymes Work Enzymes have active sites Enzyme-substrate complex Bind to specific spot on substrate Can put substrates together or break them apart Two theories to explain how Lock and key Induced fit Mills 2012

Metabolism: Energy and Enzymes 6.3 Metabolic Pathways and Enzymes Fit together like a lock and key Hydrogen proxide catalase Water and oxygen Synthesis catalase Mills 2012 Degradation

Metabolism: Energy and Enzymes 6.3 Metabolic Pathways and Enzymes Induced fit Once enzyme substrate complex has formed, enzyme changes shape slightly for a better fit Mills 2012

Metabolism: Energy and Enzymes 6.3 Metabolic Pathways and Enzymes Mills 2012

Mills 2012

Metabolism: Energy and Enzymes 6.3 Metabolic Pathways and Enzymes Factors affecting ezymatic speed Many factors can affect enzyme action Substrate concentration Temperature pH Enzyme concentration Enzyme inhibition Enzyme co-factors Affect only the rate of the reaction, not the amount of end products Only very small amounts of enzyme are needed to catalyze reactions The enzyme catalase (present in our liver) can break up 5 Million molecules of hydrogen peroxide in one minute (at Oo C = 32o F). Mills 2012

Metabolism: Energy and Enzymes 6.3 Metabolic Pathways and Enzymes Read Lab 2 – Enzyme Catalysis Oct 14th lab in your AP Lab Manual pg Mills 2012

Metabolism: Energy and Enzymes 6.3 Metabolic Pathways and Enzymes What is optimal temp for this enzyme in Fahrenheit degrees? Temperature Generally higher temp increases rate of reaction In living tissues, don’t want high temp Enzymes work best at optimal temp Usually the normal temp of the cell they are in If temp too high enzymes are denatured Boiled egg Formula: oF = (9/5) oC + 32 oF = (9/5) o42 + 32 = 107.6oF Mills 2012

Metabolism: Energy and Enzymes 6.3 Metabolic Pathways and Enzymes Enzyme and substrate concentrations Increasing the amount of substrate or enzyme will increase the reaction rate, but only up to a maximum point Maximum point – adding more enzyme will not increase rate any more. Start Fixed amount of substrate-add more and more enzyme. Mills 2012

Metabolism: Energy and Enzymes 6.3 Metabolic Pathways and Enzymes Maximum point – adding more substrate will not increase rate any more. Start Fixed amount of enzyme- add more and more substrate. Mills 2012

Metabolism: Energy and Enzymes 6.3 Metabolic Pathways and Enzymes pH Enzymes also have an optimal pH at which they work best Optimal pH for pepsin? Where might you find it? Optimal pH of trypsin? Mills 2012

Metabolism: Energy and Enzymes 6.3 Metabolic Pathways and Enzymes Enzyme inhibition Competitive inhibition Molecule binds and blocks active site Mills 2012

Metabolism: Energy and Enzymes 6.3 Metabolic Pathways and Enzymes Enzyme inhibition Non-competitive inhibition Molecule does not bind to active site, binds to allosteric site Feedback inhibition (see next slide) works this way Mills 2012

Metabolism: Energy and Enzymes 6.3 Metabolic Pathways and Enzymes Feedback Inhibition Many biological systems (metabolic pathways)work this way Mills 2012

Mills 2012

Metabolism: Energy and Enzymes 6.3 Metabolic Pathways and Enzymes Enzyme cofactors Some enzymes are not made entirely of protein, contain other substances that help them function These are substances are called cofactors Can be inorganic (such as minerals Cu, Zn, Fe) or , Can be organic- called coenzymes organic –non protein (such as vitamins) Some vitamins are coenzymes Humans cannot synthesize most vitamins, so need to take in diet Help enzyme perform it’s function Mills 2012

Metabolism: Energy and Enzymes 6.4 Organelles and the Flow of Energy Oxidation and Reduction Occur together = redox Oxidation = loss of electrons In living systems H often accompanies the electron (usually as e- + H+) So usually means loss of hydrogen atom Reduction = gain of electrons So usually means gain of hydrogen atom Mills 2012

Metabolism: Energy and Enzymes 6.4 Organelles and the Flow of Energy Two energy capturing pathways that use redox reactions (we will look at in the next two chapters) Photosynthesis – Ch 7 Cell respiration – Ch 8 Both systems make use of an electron transport system and produce ATP We will look closer at these systems in chapters 7 and 8. Mills 2012

Metabolism: Energy and Enzymes 6.4 Organelles and the Flow of Energy Photosynthesis overview Takes energy from the sun and converts it into chemical energy Equation Summarizing Photosynthesis 6CO2 + 12H2O  C6H12O6 + 6H2O + 6O2 Light Mills 2012

Metabolism: Energy and Enzymes 6 Metabolism: Energy and Enzymes 6.4 Metabolic Pathways and Oxidation Reduction Photosynthesis overview Many reactions involved At one point, a coenzyme called NADP+, is used to carry electrons from one place to another – usually to the ETS NADP+ + 2e- + H+  NADPH Mills 2012

Metabolism: Energy and Enzymes 6.4 Organelles and the Flow of Energy Cell Respiration Overview Takes energy from glucose and makes ATP Equation summarizing cell respiration C6H12O6 + 6H2O + 6O2  6CO2 + 12H2O + 36 ATP + heat Uses coenzyme NAD to carry electrons to ETS NAD+ (is reduced) + 2e- + 2H+  NADH + H+ Oxidation Reduction Mills 2012

Metabolism: Energy and Enzymes 6.4 Organelles and the Flow of Energy Electron Transport System Overview Series of carrier molecules that pass electrons along Electrons lose a little bit of energy each time passed Carriers are oxidized and reduced Mills 2012

Mills 2012

Metabolism: Energy and Enzymes 6.4 Organelles and the Flow of Energy Will discuss in more detail later Mills 2012

Metabolism: Energy and Enzymes 6. 4 6 Metabolism: Energy and Enzymes 6.4 6.4 Organelles and the Flow of Energy ATP Production Overview Uses energy from ETS ETS located within membranes of mitochondria and chloroplasts Process called chemiosmosis ETS deposits H on one side of the membrane H flow down electrochemical gradient through ATP synthase complex Flowing through the complex provides the energy to add a P to ADP  ATP Mills 2012 Animations from http://www.cat.cc.md.us/courses/bio141/lecguide/unit4/metabolism/cellresp/etsch.html

Metabolism: Energy and Enzymes 6.4 Organelles and the Flow of Energy Chemiosmosis blah, blah blah, blah blah, blah blah, blah blah, blah….. Peter Mitchell 1978 Nobel Prize Chemiosmosis Theory Mills 2012

ATP synthesis and the electron transport chain animation Mills 2012

Metabolism: Energy and Enzymes 6.4 Organelles and the Flow of Energy Chemiosmosis website animation From: http://www.tvdsb.on.ca/westmin/science/sbioac/plants/chemios.htm Mills 2012

Read Connecting the Concepts with the Big Ideas pg 115 The End Mills 2012