BME50A – W2016 – HW4 Question 1 You have two molecules, a protein (A) and a piece of DNA (B). They bind reversibly as described in the following reaction: A + B AB This is a favorable reaction such that the ΔG0 of this reaction is -15 kcal/mol. a) You want to engineer the binding between A and B to be even stronger. Specifically, you would like the ratio [AB]/([A][B]) at equilibrium to be 10 times greater than it was before. By how much do you have to decrease (make more negative) the ΔG0 of this reaction in order to achieve this? (Look up constants as necessary.) b) How many hydrogen bonds does that correspond to? (Look up the energy of a hydrogen bond if you don’t recall from base pairing.)Question 2 Cancer cells exhibit what’s called the Warburg effect: even in the presence of oxygen, rapidly growing cancer cells produce energy by a high rate of glycolysis and fermentation. As a result, the cells make ATP less efficiently than normal cells, which take the products of glycolysis and covert them to CO2 (which we breath out) in the citric acid cycle. Why do you think rapidly growing cancer cells prefer doing this?Question 3 (from the book) 483t 5IF QIPUPTZOUIFUJD FMFDUSPOUSBOTQPSU DIBJOT JO DIMPSPQMBTUT BMTPgenerate a proton gradient across the thylakoid membrane, which is used by an ATP synthase embedded in the membrane to generate ATP.t 5IF "51 BOE UIF /"%1) NBEF CZ QIPUPTZOUIFTJT BSF VTFE XJUIJOthe chloroplast stroma to drive the carbon-fixation cycle, which pro-duces carbohydrate from CO2 and water.t $BSCPIZESBUFJTFYQPSUFEGSPNUIFTUSPNBUPUIFDFMMDZUPTPMXIFSFit provides the starting material for the synthesis of other organic molecules. t #PUI NJUPDIPOESJB BOE DIMPSPQMBTUT BSF UIPVHIU UP IBWF FWPMWFEGSPNCBDUFSJBUIBUXFSFFOEPDZUPTFECZPUIFSDFMMT&BDISFUBJOTJUTown genome and divides by processes that resemble a bacterial cell division.t $IFNJPTNPUJD DPVQMJOH NFDIBOJTNT BSF PG BODJFOU PSJHJO .PEFSOmicroorganisms that live in environments similar to those thought to IBWFCFFOQSFTFOUPOUIFFBSMZ&BSUIBMTPVTFDIFNJPTNPUJDDPVQMJOHto produce ATP.antenna complex mitochondrionATP synthase nitrogen fixationcarbon fixation oxidative phosphorylationcell respiration photosynthesischemiosmotic coupling photosystemchlorophyll quinonechloroplast reaction centercytochrome redox paircytochrome c oxidase redox potentialdark reactions redox reactionelectron-transport chain respiratory enzyme complexiron–sulfur center stromalight reactions thylakoidsmatrixKEY TERMS QUESTION 14–11Which of the following statements are correct? Explain your answers. A. After an electron has been removed by light, the affinity for electrons of the positively charged chlorophyll in the reaction center of the first photosystem (photosystem II) is even greater than the electron affinity of O2.B. Photosynthesis is the light-driven transfer of an electron from chlorophyll to a second molecule that normally has a much lower affinity for electrons.C. Because it requires the removal of four electrons to release one O2 molecule from two H2O molecules, the water-splitting enzyme in photosystem II has to keep the reaction intermediates tightly bound so as to prevent partly reduced, and therefore hazardous, superoxide radicals from escaping.QUESTION 14–12Which of the following statements are correct? Explain your answers.A. Many, but not all, electron-transfer reactions involve metal ions.B. The electron-transport chain generates an electrical potential across the membrane because it moves electrons from the intermembrane space into the matrix.C. The electrochemical proton gradient consists of two components: a pH difference and an electrical potential.D. Ubiquinone and cytochrome c are both diffusible electron carriers.E. Plants have chloroplasts and therefore can live without mitochondria. QUESTIONSChapter 14 End-of-Chapter QuestionsQuestion 4 I start with one molecule of a circular DNA plasmid and two PCR primers (in large molar excess) that prime specifically where shown. (The primers are represented as the orange and red arrows.) I want to amplify the region defined by these primers to give me the desired linear duplex DNA product. Assuming 100% priming efficiency, after 2 cycles of PCR, how many full exact molecules of the desired amplified product do I have? What about after 4 cycles? What about after 10 cycles? Desired