Bio 1 Exam 2 Review
Bio 1 Exam 2 Review BIOSC 0150
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This 6 page Study Guide was uploaded by Spencer Poston on Saturday February 21, 2015. The Study Guide belongs to BIOSC 0150 at University of Pittsburgh taught by Kaufman/McGreevy in Spring2015. Since its upload, it has received 128 views.
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Date Created: 02/21/15
Foundations of Biology Exam 2 Review First let s review energy What kinds of energy are there 0 Potential stored energy ability to do work 0 Kinetic work the actual movementenergy that s doing the task 0 Other heat sound light energy that is the result of the task can t be used How do we store energy 0 Position of electrons in atoms and molecules the further an electron is from the nucleus the higher its energy 0 Chemical gradients Laws of Energy and Thermodynamics First Law energy is neither created nor destroyed only transformed Second Law some energy becomes unusable when energy is transformed every time we convert energy Redox Reactions are a common method for transferring energy between molecules in the form of electrons Oxidize loss of electrons l more positive charge Reduction gain of electrons more negative charge quotreduced charge Ex In cellular respiration glucose is oxidized and oxygen is reduced The cell uses electron carriers NAD and FAD to transfer high energy electrons from one reaction to another Energy is not created or consumed so they are called quotcarriersquot 0 FAD is oxidized when it picks up 2 electrons and 2 H protons so it becomes FADH2 NAD is oxidized when it picks up 2 electrons and 1 H proton so it becomes NADH These carriers will become very important in later processes ATP and ADP Adenosine Triphosphate and Adenosine Diphosphate are named for their phosphate groups They are high in energy because multiple phosphates aligned next to each other create a very unstable environment Phosphorylating a protein enzyme can cause a shape change that can drive a chemical reaction Formfunction l changing shapechanging function Kinase the enzyme that transfers phosphate to another molecule phosphorylates it When an enzyme is phosphorylated its potential energy for future reactions is raised This raises the energy of the enzymesubstrate complex pushing it to carry out its function Before we continue what else do you need to know about enzymes What in uences the rate of a reaction 0 Factors like Delta G free energy heat concentration temperature pH and activation energy Ea How do enzymes affect the rate of a reaction 0 They can affect certain factors like concentration and orientation 0 Most importantly enzymes lower the activation energy needed to trigger a reaction This is what catalyzes and makes the reaction go faster Induced fit many enzymes change shape upon binding to substrates because of electron sharing This allows for a quotperfect fitquot between the two entities that lends itself to speci city among enzymes and substrates Are enzymes limited 0 An enzyme can only speed up a reaction so much At a set enzyme concentration there is a maximum speed for a given reaction called the Vmax When the Vmax is reached every active site is making product 0 Km the amount of substrate concentration that meets with half of Vmax o Enzymes all have an ideal environment to act in depending on pH and temperature lsozymes enzymes that catalyze the same reactions but in different ways and at different rates Sometimes enzymes can only function with partners called cofactors inorganic ions or coenzymes small organic molecules If this partnership is permanent the enzyme has a prosthetic group which means the coenzyme is covalently bonded to it How is enzyme behavior regulated 0 Competitive inhibition a molecule that is very similar to the enzyme is able to bind to the active site at the substrate instead so the reaction is unable to proceed Allosteric regulation a regulatory molecule binds to an allosteric site somewhere other than the active site This can either inhibit or encourage the reaction 0 Feedback inhibition involved in pathway reactions the product of a reaction is able to circle back to the beginning of the process and inhibit it from continuing Carbohydrates How do we classify them 0 The location of their carbonyl o On end of chain aldose o In middle of chain ketose Number of carbons o 3triose 5pentose 6hexose etc o A speci c name is then given upon discovery glyceraldehyde glucose ribose Carbs also vary on the arrangement of their atoms and which direction the hydroxyl is pointing in Alpha away from 6 C Beta in same direction as 6 C What difference does the hydroxyl orientation make on the function of the carb Alpha and Beta describe the glycosidic linkages that hold the monosaccharaides together and each have different characteristics Alpha used in energy and storage We get alpha linkages from the foods we eat and they are easy to break down and use for energy Beta used in structure These bonds are much tougher than alpha and our body doesn t have the enzymes needed to break them down So they go towards cell structure instead Energy is stored in the CH bonds of carbohydrates Cellular Respiration the breakdown of glucose Overview 1 Glycolysis in cytosol a b C Steps 13 are the Energy Investment steps 2 ATP invested and 2 G3P molecules are created Steps 710 are the Energy Payoff steps 4 ATP are created total 2 of which cancel out the investment ATPs The G3P molecules become pyruvate Glycolysis produces 2 ATP 2 pyruvate molecules and 2 NADH 2 Pyruvate Oxidation in matrix a b C NAD is reduced to NADH Pyruvate dehydrogenase attaches Coenzyme A to Acetyl forming Acetyl CoA Pyruvate produces 2 NADH and 2 Acetyl CoA molecules 3 Citric Acid Cycle in matrix a b C The Acetyl CoA binds to oxaloacetate triggering cycle to begin Citrate is oxidized causing 3 NAD to reduce to 3 NADH and 1 FAD to 1 FADH2 Citric Acid Cycle produces for 2 pyruvate molecules 6 NADH 2 FADH2 2 ATP 4 Electron Transport Chain membraneintermembrane space a b Protein Complexes 14 take in electrons from electron carriers NADH and FADH2 pumping out H protons in return The H protons oat in intermembrane space until they come to ATP synthase which takes them in and pumps out ATP in return Different amounts ATP are produced here depending on the organism but it s always the biggest yield Cellular Respiration is an aerobic process meaning it needs oxygen to occur So what if oxygen isn t present Fermentation This process involves only glycolysis so it produces very little energy lts job is to continue to produce NAD so that glycolysis is able to continue and produce ATP Lactic Acid fermentation when pyruvate becomes lactate Lactic Acid is what builds up in our muscles when we are working out heavily we re not able to get enough oxygen to our cells as quickly as they need it so it resorts to fermentation Ethanol fermentation humans are not capable of this kind of fermentation but it is common in the process of making beer and wine If humans use cellular respiration to produce energy what do plants do Photosynthesis C02 H20 Sunlight Sugar glucose Oxygen H20 0 Where does it take place Leavesstem In which organelle Chloroplasts o What is the source of oxygen Water As you can see from the equation plants take in C02 useless to us and give back oxygen for us to breath and sugar for us to convert into energy This is why plants and trees are so vital to our own existence They also have the unique ability to turn light energy into chemical energy something not possible in humans What is light It is a form of electromagnetic radiation that is characterized by its wavelength The shorter its wavelength the higher its energy is and vice versa Out of visible light purpleblue light has the highest energy shortest wavelength and red light has the lowest energy longest wavelength Remember that an electron s energy is characterized by its distance from the nucleus When an electron absorbs light it becomes excited and is moved to a higher level of energy further from the nucleus Components of Photosynthesis Mesophyll cells contain chloroplasts where the process occurs Stroma water based uid around chloroplast o Tylakoid membrane with uid inside found within chloroplast o Pigments controls color They absorb only certain wavelengths of light if not absorbed the light will be re ected or transmitted which we see as color Pigments in plant chloroplasts do not absorb green light so that re ected green light is what we see in the color of the leaves and stem lt s highly recommended to reference photosynthesis videos online These will provide a better visual of how photosynthesis creates energy and sugar I ve provided the components and background info in hopes that they will make understanding the videos easier
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