Chapter 5.2 & 5.3: The Dynamic Cell - Energy & Enzymes - PDF

Here is the transcription of the document in markdown format: # Chapter 5.2 and 5.3 – The Dynamic Cell The image shows a firefly. ## Energy The capacity to do work or to change matter ## Types of Energy * Kinetic energy - the energy of motion The image shows moose in a marsh * Solar ener...

Here is the transcription of the document in markdown format: # Chapter 5.2 and 5.3 – The Dynamic Cell The image shows a firefly. ## Energy The capacity to do work or to change matter ## Types of Energy * Kinetic energy - the energy of motion The image shows moose in a marsh * Solar energy * Heat * Chemical energy * Mechanical energy ## Types of Kinetic Energy * Mechanical Energy * (moving matter such as a car or you muscles) * Electrical Energy * (movement of charged particles: nerve impulses, electricity) * Radiant energy * (energy that moves in waves: heat, microwaves, etc.) ## Types of Energy * Potential Energy * stored or inactive energy * Example: water behind a dam. The water is not producing energy while it is behind the dam, but it has the potential to do so if it is released. The image is of a dammed up river or lake ## Types of Potential Energy * Chemical energy - energy stored in chemical bonds (example - ATP). $ADP + P \rightarrow ATP$ ## Thermodynamics Thermodynamics - the study of energy and its transformations. ## First law of thermodynamics First law of thermodynamics – energy cannot be created or destroyed, but it can be changed from one form to another. The image shows moose in a landscape being affected by solar enery. * Solar energy * Heat * Chemical energy * Mechanical energy ## Second law of thermodynamics Second law of thermodynamics – energy cannot be changed from one form to another without a loss of usable energy. In living systems, energy is lost in the form of heat. ## Entropy The relative amount of disorder or disorganization. Each energy transformation that occurs increases the amount of entropy (disorder) in the universe. Therefore, the entropy in the universe is continually increasing. The image shows the chemical formula of glucose and its break down into water and carbon dioxide. * $C_6H_{12}O_6$ * Glucose * more organized * more potential energy * less stable (entropy) * $H_2O$ * $CO_2$ * Carbon dioxide and water * less organized * less potential energy * more stable (entropy) ## Metabolic Reactions and Energy Transformations Metabolic Reactions Metabolic reactions are chemical reactions that involve energy transformations. Generally metabolic reactions are reversible. So if $A + B \rightarrow AB$ then you can also have $AB \rightarrow A + B$. It is important that all chemical reactions are theoretically reversible. In truth, some are more reversible than others. ## Equilibrium Chemical equilibrium - where the concentrations of reactants and product are constant. Reversible reactions will reach a chemical equilibrium $A + B \rightleftharpoons AB$ ## Chemical reactions Reactants – the substance(s) that participate in the reaction. What you begin the reaction with. Products – the substance(s) that are produced by the reaction. What the reaction ends with. Arrow will ALWAYS point to your product ## Chemical reactions So for the chemical reaction: $A + B \rightarrow AB$ ## Chemical Reactions $A + B \rightarrow AB$ A and B are the reactants and AB is the product. The arrow shows the direction in which the reaction will go. ## Types of Chemical Reactions Endergonic reactions – require the input of energy Exergonic reactions - are reactions that release energy ## ATP - adenosine triphosphate Images showing ATP. # ATP This energy is used for: * chemical work – used to synthesize macromolecules * transport work – used to move materials across the plasma membrane (example – active transport, phagocytosis etc.) * mechanical work – used to contract muscles, move cilia and flagella etc. ## Metabolic Pathways Biosynthetic pathways - metabolic pathways that build larger molecules from smaller molecules. $A + B \rightarrow AB + C \rightarrow ABC + D \rightarrow ABCD$ ## Metabolic Pathways Degradative pathways - metabolic pathways that break down molecules. $ABCD \rightarrow ABC +D \rightarrow AB + C + D \rightarrow A + B + C + D$ ## Metabolic Pathways In cells (and multicellular organisms) each step in a metabolic pathway is catalyzed by an enzyme. ## Enzymes Proteins that act as biological catalysts ## Characteristics common to all enzymes 1. All enzymes are proteins. 2. All enzymes are biological catalysts that speed up chemical reactions. However, enzymes will not cause a chemical reaction to occur that would not occur naturally ## Characteristics common to all enzymes 3. All enzymes are specific for their substrate (a substrate is a substance that the enzyme acts upon). 4. All enzymes simply help a chemical reaction occur (therefore they speed up chemical reactions). However, the enzymes does not become part of the product and is not used up by the reaction. ## Energy of Activation The energy that must be added to cause molecules to react with each other. Enzymes lower the energy of activation required for a chemical reaction to occur The image is a graph. ## Substrate A substance that the enzyme acts upon. ## Active Site Active Site - the place on the enzyme where the substrate binds. ## Enzyme-Substrate Complex The combination of enzyme and substrate where the substrate enters and binds to the active site on the enzyme. ## Lock and Key Model A model which has the enzyme and active site fitting exactly together – like a lock and key! ## Induced Fit Model A model in which the substrate moves into the active site of the enzyme and the active site molds around the substrate ## Factors affecting enzyme activity Substrate concentration - the more concentrated a substrate the faster an enzyme will react. ## Factors affecting enzyme activity * Temperature and pH - enzymes work better with warmer temperatures and a neutral pH. However, if temperature rises too much, the enzyme could be denatured and not be usable. pepsin and trypsin. ## Factors affecting enzyme activity Enzyme concentration - the more concentrated an enzyme is, the faster the reaction will occur. Cells regulate this by regulating gene expression – the amount of protein that is produced from a gene. Remember that enzymes are proteins! ## Factors affecting enzyme activity Cofactors - "enzyme helpers”. These are molecules that are necessary for an enzyme to function. Cofactors are inorganic ion or organic (but nonprotein) molecules. Coenzymes - The term Coenzyme is usually given to the organic (but nonprotein) molecules. They are the organic enzyme helpers ## Factors affecting enzyme activity Enzyme inhibition - when the active enzyme is prevented from combining with its substrate. There are three types of enzyme inhibitors ## Enzyme Inhibitors competitive inhibitors – where a molecule binds to the active site and prevents the substrate from binding. ## Enzyme Inhibitors non-competitive inhibitors – where a molecule binds to the enzyme and changes the shape of the active site and prevents the substrate from binding. ## Enzyme Inhibitors feedback inhibition - Where the end product of a metabolic pathway binds to the enzyme and prevents it from binding with its substrate. ## Enzyme Cycle Enzyme + Substrate → Enzyme substrate complex → Product + Enzyme The Enzyme then can bind with another substrate ## Metabolic Pathways and Oxidation-Reduction Reactions ## Oxidation-Reduction Reactions Oxidation – the loss of electrons from a molecule Reduction – the gain of electrons from a molecule ## Oxidation-reduction (redox) reactions Reactions that occur when one molecule is oxidized and another molecule is reduced. These reactions occur in cellular respiration and photosynthesis. ## Oxidation-reduction (redox) reactions Photosynthesis – in living things, hydrogen ions ($H^+$) often accompany electrons. Photosynthesis uses oxidation/reduction reactions to transfer electrons (and hydrogen ions) from water to carbon dioxide to make glucose. We will talk about photosynthesis in Chapter 7. ## Oxidation-reduction (redox) reactions Cellular respiration – This reaction is the reverse of photosynthesis. Glucose loses hydrogen ions (and electrons) and produces carbon dioxide and water. In the process energy is released and is used to make ATP (primarily in the mitochondria). We will talk about cellular respiration in Chapter 8. ## Electron transport systems Electron Transport Systems usually abbreviated ETS. Is a series of membrane bound carriers that pass electrons from one carrier to another. Stair graph showing how an election goes from high-energy electrons to low-energy electrons. ## Electron transport systems We are going to see ETS's coupled with an enzyme called ATP synthase that will be used to produce ATP. ## ATP Production ATP synthase complexes – enzymes and their carrier proteins that form a complex that is embedded in the membrane of mitochondria or chloroplasts. ## ATP Production These complexes use the flow of hydrogen ions (moving through the membrane from high concentration to low concentration) to generate ATP. ## ATP Production Chemiosmosis – the term for the production of ATP using a hydrogen ion gradient across a membrane.