Bio 201 1st Edition Lecture 17 Outline of Last Lecture I. GPCR’sA. ExperimentB. How cAMP activates PKAII. GPCR Signal TransductionA. Desensitization B. Tissue SpecificityOutline of Current LectureI. Last of Signal TransductionA. Receptor Tyrosine Kinases and RasB. Steroid Hormone ReceptorsII. Basic ThermodynamicsA. 1st LawB. 2nd LawC. Gibbs Free Energy III. ATPCurrent LectureI. Last of Signal Transduction A. Receptor Tyrosine Kinases and Ras- RTK binds to growth factor, Ras result in gene transcription in the nucleus, mutation of Ras can cause cancer (found in 1/3 of humancancer) because it decreases GTPase activity, which prevents Ras ability to turn itself off.These notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.B. Steroid Hormone Receptors- Intracellular receptors that regulate gene transcription through direct DNA-binding. Can stimulate or suppress gene transcription. Gene transcription is slow but long-lasting. II. Basic ThermodynamicsA. 1st Law- Energy can neither be created nor destroyed, energy of a closed system is conserved, but energy can be converted between forms. B. 2nd Law- The entropy (disorder) of a closed system tends to increase. Energy is neededto decrease entropy. Increased EntropyLoss of cellular integrity DEATH Endergonic- requires energy, decreases entropy, spontanous (polymerization) Exergonic- releases energy, increases entropy, not spontaneous (depolymerixation)C. Gibbs Free Energy (G)- The total energy of a system. We cannot exactly measure the G so we measure ΔG. ΔG= G products- G reactants. If ΔG<0, total energy of the system decrease and reaction is exergonic. If ΔG>0, totally energy of the system increases and the reaction is endergonic. TO DETERMINE ΔG: 1. Start with 1M of all reactants and products. 2. Let reaction reach equilibrium. 3. Measure M of reactants and products. 4.Calculate equilibrium constants Keq= Mproduct of products/ Mproduct or reactants. 5. ΔG= -RT lnKeq or ΔG=-2.303RT logKeq. If Keq> 1 then G<0 and the reaction is exergonic. If Keq<1 then G>0 and the reaction is endergonic. III. ATP- Where all cells get their energy. ATP has 2 high energy bonds, when broken, energy is released. Energy coupling- Creation of high-energy phoshphorylation of reaction leads to
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