BIOL 1201 Exam 2 Study Guide Energy Flow in Cells Energy capacity to do work Kinetic Energy energy of movement mv2 90 efficient Potential Energy stored energy energy is lost to heat positional Laws of Thermodynamics o Ex Light heat electricity electrons move through a wire plants do this really well o Ex Chemical energy batteries plug phones in at night electrically stored some o 1st Law Conservation of Energy amount of energy in a system remains constant Can define system as whatever you want it to be can be open or closed This statement has a lot of variables to take into account o 2nd Law When energy is converted form to another useful energy decreases Useful is a relative term to what you are talking about who you are talking to Entropy a measure of disorder increases o Bonds represent stored energy o Ex 100 units of chemical energy gas combustion by engine 75 units heat energy exhaust 25 units kinetic energy motion when you take your foot off the gas kinetic energy goes to friction all the energy can be accounted for low entropy high Energy Flow on Earth o Outputs mainly heat Energy Flow in Chemical Reactions o Input from the sun photoautotrophs plants other producers heterotrophs consumers decomposers we get energy from plants o Chemical reactions forming breaking of chemical bonds General rule forming requires energy breaking releases energy o Reactants aka substrates starting materials o Products results of the reaction o Exergonic Reactions A B C D High energy reactants Low energy products A B have more energy than C D energy is released in the reaction Ex Cellular Respiration o Endergonic Reaction C D A B Low energy reactants High energy products C D have less energy than A B energy is added into the reaction Ex Photosynthesis o Graphically Initial end amount of energy needed released Hump activation energy energy needed to start the reaction cells use enzymes as catalysts so the cell doesn t have to use as much energy to complete the reaction o Coupled Reactions Exergonic ATP 100 units energy released ADP P Endergonic relaxed muscle 20 units energy contracted muscle Coupled Reaction relaxed muscle ATP contracted muscle 80 units energy released as heat ADP P ATP adenine triphosphate be able to recognize High energy content ADP adenine diphosphate Low energy content GDP GTP can also do this Phosphorylation adding of a phosphate to a particular substance Example within Living Cells Glucose exergonic glucose breakdown CO2 H2O heat o 1st Step lice glucose split into 2 3 C chains called glycolysis then onto Krebs Cycle When glucose is broken down energy is released Some is lost in heat but others are transformed to other uses of energy ATP synthesis endergonic ATP breakdown exergonic Synthesis of ATP readily available energy o Need ADP Free Phosphate Energy o Yields ATP all the energy isn t stored in the bonds of ATP never all Breakdown of ATP releasing energy for work o Need ATP o Yields ADP Free Phosphate Energy Amino Acids endergonic protein synthesis protein Metabolism sum of all the chemical reactions in a cell Metabolic Pathways series of reactions linked in a sequence aka enzyme pathways o Most reactions are catalyzed reactions o Exergonic Endergonic Metabolism o like a car being built in a factory o Initial Reactants substrates o Intermediates Enzyme 1 recognizes A as a substrate catalyzes the reaction to produce product B Enzyme 2 recognizes B as a substrate catalyzes the reaction to produce product C Enzyme 3 recognizes C as a substrate catalyzes the reaction to produce product D o Final Product Enzyme 4 recognizes D as a substrate catalyzes the reaction to produce product E o Pathway 2 Enzyme 5 recognizes C as a substrate catalyzes the reaction to produce F which is then recognizes by enzyme 6 as a substrate catalyzes the reaction to produce product G o Hypothesis one gene one protein one strand of DNA will product one certain kind of protein true to an extent Controlling Metabolism o PROTEINS CONTROL JUST ABOUT EVERYTHING o Enzymes regulate chemical reactions o Cells couple reactions o Energy carriers capture energy from exergonic reactions deliver to endergonic reactions Catalysts o Speed up chemical reactions o Enzymes are biological catalysts Usually proteins RNA Ribozymes are not proteins but are catalysts o Activation Energy controls rate or reaction Enzymes speed up chemical reactions by lowering activation energy o Properties of Biological Catalysts 1 Speed up reactions 2 Speed up reactions that would occur anyways cannot speed up reactions that won t happen won t change anything just speed it up 3 Not consumed in reactions 4 Enzymes are very specific 5 Enzyme activity is regulated they can be turned on or off like a light switch 1 3 are all catalysts 4 5 specific to enzymes Enzyme Substrate Interactions o 1 Substrates enter active o 2 Shape change promotes site reaction o 3 Product released enzyme ready again o Active Site 3D crater in the enzyme with specific amino acids to hold onto substrates a certain way to hold onto the substrates such that when they bind they are in jus the right orientation change the shape of the protein just enough leading to the reaction to take place release the product R groups sticking out into the active site dozens of these active sites sticking out cause enzyme to grab onto proteins o Will happen over over unless the protein is degraded or the process is told to stop Enzyme Regulation o Regulate synthesis Transcribing DNA into RNA Actively degregate RNA Inhibit RNA to transcript proteins post translationally o Make them inactive activate when needed post translationally Feedback inhibition If there are too many made their stock piles up cut off the beginning of making the product Our cells take 8 essential amino acids transform them into the other 12 by catalyzing reactions with enzymes Substrate enzyme 1 enzyme 2 enzyme x end product Ex Threonine is made into Isoleucine by 5 different chemical reactions 5 different enzymes The end product can come attach to enzyme 1 inhibit that same end product by noncompetitive or competitive inhibition Allosteric regulation noncompetitive Allosteric changing the shape Noncompetitive inhibition end product binds to another site besides the active site changes the shape of the protein so the active site is no longer on for the substrate to bind to Enzyme has an active site an allosteric regulator site which the end product will bind to instead of the active site to change the
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