Mrna is altered after transcription proteins are made

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mRNA is altered after transcription Proteins are made of many polypeptide chains Protein modification occurs by Adding a lipid or carbohydrate Adding a phosphate group Cutting into small units Chapter 3: Cellular Metabolism - Reactions o A + B > C + D; A&B are reactants; C&D are products o Things are more complicated than this in a living cell o Ex: cellular respiration C 6 H 12 O 6 + 6O 2 > 6CO 2 + H 2 O Sugar + oxygen > carbon dioxide + water This equation represent cellular respiration ; we will talk about it a lot more later Breaking down food actually produces water o But this situation almost never happens: A + B > C + D o In reality: A + B <> C + D Reaction proceeds in both forward and reverse directions at the same time; it is bidirectional If the forward arrow is bigger than the reverse arrow, more reactants are converted to products than the other way around. Net movement in the forward direction o Catabolic vs. Anabolic Reactions Catabolic reaction: breakdown of larger molecules into smaller molecules; release energy Anabolic reaction: production of larger molecules from smaller molecules; requires energy Known in steroids = steroids build muscle o Bioenergetics First Law of Thermodynamics: energy cannot be destroyed or created, only transferred/transformed Can’t make any more energy and can’t get rid of the energy that we already have Ultimate source of energy in universe = the SUN Conversion of light energy into glucose by plants o All the energy of the Sun gets transferred and transformed but it stays in the universe Second Law of Thermodynamics : with every transfer or transformation of energy, some useable energy (energy that could have been used to do work) is released as heat
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13 There isn’t a 100% perfect amount of transferable energy because there is always heat involved o Ex: working out on the treadmill Ex: 100 units of potential energy (free energy) > 75 units kinetic energy (thermal) + 25 units kinetic energy (motion) o Useable energy: energy that can do work o Non-useable energy: heat or the disorder o Endergonic vs. Exergonic Reactions Endergonic reactions : chemical reactions that require an input of energy. Products contain more free energy than the reactants. Energetically uphill Ex: start off with reactants with low energy and ended up with products with high energy = energy must have been added Exergonic reactions : chemical reactions that release energy. Products will have less free energy than the reactants. Energetically downhill Ex: start off with reactants with high energy and end up with products with low energy = energy must have been transferred or transformed Exergonic reactions tend to proceed spontaneously Endergonic reactions do not proceed spontaneously, only when energy is put into them How do endergonic reactions in physiology occur?
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