Learning Objectives: LO 2.4 The student is able to use representations to pose scientific questions about what mechanisms and structural features allow organisms to capture, store and use free energy. [See SP 1.4, 3.1] Ch.10 LO 2.5 The student is able to construct explanations of the mechanisms and structural features of cells that allow organisms to capture, store or use free energy. [See SP 6.2]

Chapter 8 Metabolism is all of an organism’s chemical processes. Macromolecules are broken down and synthesized. The 2 types include catabolism-a pathway that releases energy by breaking down complex molecules-polymers. Anabolism is a pathway that consumes energy to build complicated molecules from simple ones. Ex. Photosynthesis 2. Energy is the capacity to do work. Potential energy is energy that mass contains because of its location are arrangement. Kinetic energy is the process of doing work. Food and energy Metabolism Energy and Life On the platform, a diver has more potential energy. Diving converts potential energy to kinetic energy. Climbing up converts kinetic energy of muscle movement to potential energy. In the water, a diver has less potential energy.

Chapter 8 1. 1st law of thermodynamics- energy can be transferred and transformed but cannot be created or destroyed. Energy comes from surroundings. 2. 2nd law of thermodynamics every energy transfer or transformation makes the universe more disordered- (entropy)(S). Entropy increases. B. Laws of thermodynamics and energy transformation (a) First law of thermodynamics: Energy can be transferred or transformed but neither created nor destroyed. For example, the chemical (potential) energy in food will be converted to the kinetic energy of the cheetah’s movement in (b). Second law of thermodynamics: Every energy transfer or transformation increases the disorder (entropy) of the universe. For example, disorder is added to the cheetah’s surroundings in the form of heat and the small molecules that are the by-products of metabolism. (b) Chemical energy Heat co2 H2O +

Chapter 8 1.Organism live at the expense of free energy. This allows spontaneous change. All of a systems energy is not available to do work. The energy that is available to do work is called Free energy (G). It is a product of total energy or ethalpy(H) minus Temp.(T) K-Kelvin and entropy (S) Δ G = H – TΔS know each.symbol Δ G is an endergonic RXN-that requires energy K = Celsius + 273 This helps determine if RXN is spontaneous or not. Spontaneous RXN= Δ G<0 a negative value means it spontaneous. C. Metabolism Energy and Life

Chapter 8 ∆G = –3.9 kcal/mol D. Free energy and metabolism Reactions can be classified based upon their free energy changes Exergonic RXN proceed w/ a net loss of free energy. They are spontaneous RXN that go down hill - Δ G is negative Endergonic RXN requires energy that proceeds w/ a gain of free energy. The RXN is uphill. +Δ G is positive At equilibrium Δ G = 0 Metabolic disequilibrium is necessary for life; a cell is dead at equilibrium. –Glucose VS CO2 Endergonic reaction: ∆G is positive, reaction is not spontaneous ∆G = +3.4 kcal/mol Glu ∆G = –7.3 kcal/mol ATP H2O + NH3 ADP NH2 Glutamic acid Ammonia Glutamine Exergonic reaction: ∆ G is negative, reaction is spontaneous P Coupled reactions: Overall ∆G is negative; together, reactions are spontaneous ∆G = –3.9 kcal/mol

Chapter 8 ∆G = –3.9 kcal/mol ∆G = +3.4 kcal/mol Glu ∆G = –7.3 kcal/mol Endergonic reaction: ∆G is positive, reaction is not spontaneous ∆G = +3.4 kcal/mol Glu ∆G = –7.3 kcal/mol ATP H2O + NH3 ADP NH2 Glutamic acid Ammonia Glutamine Exergonic reaction: ∆ G is negative, reaction is spontaneous P Coupled reactions: Overall ∆G is negative; together, reactions are spontaneous ∆G = –3.9 kcal/mol

Chapter 8 E. Free energy and metabolism Adenosine triphosphate (ATP) H2O + Energy Inorganic phosphate Adenosine diphosphate (ADP) P i ATP powers cellular work by coupling exergonic to endergonic RXN ATP undergoes hydrolysis to release energy, this free energy can be used in other reactions.

Chapter 8 Free Energy and metabolism ATP works by destabilizing a chemical by donating a P . This donation from ATP-adenosine tri- phosphate, releases 55kj/mol of energy. ATP- provides energy coupling between endergonic and exergonic reactions Cellular respiration an endergonic RXN changes ADP to ATP at 107 molecules/cell/sec

Chapter 8 Enzymes are specific for a particular substrate, and that specificity depends upon the enzymes three dimensional shape. Enzymes speed up the rate of reactions. The substrate is the substance an enzymes acts upon to make more reactive. The location on the enzyme where the binding occurs is called the Active Site . The catalyst leaves the RXN and is used again. The substrate can cause the enzyme to change shape so they fit. F. Enzymes and substrates

Chapter 8 Enzyme An Enzyme. Find it Substrate Active site Enzyme (a) Enzyme- substrate complex Chapter 8 Enzyme

(a) Optimal temperature for two enzymes (b) Optimal pH for two enzymes The optimal pH for most enzymes is 6- 8. The optimal temp. for most enzymes is 35-40 C in humans Cofactors are small non-protein molecules are needed for proper enzyme activity. They can be inorganic metal, or organic conenzymes-most vitamins Inhibitors are certain chemical that affect RXN. They can be irreversible if they use covalent bonds. They can be reversible if they use hydrogen bonds. Inhibitors can be competitive or non- competitive-poisons-DDT- Coupled reactions happen in two steps. –Ex. 1st use ATP then use the energy for a 2nd reaction. Chapter 8 G. Factors that affect the enzyme Optimal pH for two enzymes Rate of reaction 20 40 60 80 100 Temperature (Cº) (a) Optimal temperature for two enzymes (b) Optimal pH for two enzymes pH Optimal temperature for typical human enzyme enzyme of thermophilic Optimal pH for pepsin (stomach enzyme) Optimal pH for trypsin (intestinal enzyme) 1 2 3 4 5 6 7 8 9 10 (heat-tolerant) bacteria

Chapter 8 Many enzymes are allosterically regulated They change shape when regulatory molecules bind to specific sites, affecting function Competitive inhibition- another binds to activation site Non competitive-change enzyme shape Chapter 8 H. Allosteric Activation and Inhibition Active site available Isoleucine used up by cell Feedback inhibition Isoleucine binds to allosteric site Active site of enzyme 1 no longer binds threonine; pathway is switched off Initial substrate (threonine) Threonine in active site Enzyme 1 (threonine deaminase) Intermediate A Intermediate B Intermediate C Intermediate D Enzyme 2 Enzyme 3 Enzyme 4 Enzyme 5 End product (isoleucine) Figure 8.21

Chapter 6/8 Metabolic control depends on allosteric regulation. Allosteric regulation are binding sites on the enzyme other than the active site. An activator on an allosteric site, stabilizes the activity. An inhibitor on an allosteric site, stabilizes the enzymes inactivity. Control of Metabolism

Chapter 6/8 Control of Metabolism Feedback inhibition is a regulation of a metabolic pathway by its end product, which inhibits an enzyme within the pathway

Draw this graph then identify: G, activation energy, reactant, product, endergonic or exergonic d-b