BIOL111 Lecture 3 2024 PDF

3/19/24 What you should know at the end of this lecture n ATP is a cells energy shuttle n ATP hydrolysis is exergonic – in cells is coupled to endergonic reactions/processes n Coupling occ...

3/19/24 What you should know at the end of this lecture n ATP is a cells energy shuttle n ATP hydrolysis is exergonic – in cells is coupled to endergonic reactions/processes n Coupling occurs by loss/transfer of a phosphate – phosphorylated intermediates are more reactive n Catabolic pathways enable the production of ATP from ADP and Pi n All reactions have an intrinsic energy barrier (EA) (even exergonic ones with a –DG) n Enzymes lower EA and speed up reactions music 1 ATP – Adenosine triphosphate n Adenine base 2 1  3/19/24 ATP – Adenosine triphosphate n Adenine base n Ribose sugar n adenosine 3 ATP – Adenosine triphosphate n Adenine base n Ribose sugar n Adenosine n 3 Phosphates n triphosphate Base + sugar = nucleoside Nucleoside + phosphate = nucleotide 4 2  3/19/24 ATP hydrolysis and free energy DG = -7.3 kcal mol-1 5 ATP hydrolysis and free energy n Why negative DG? n ADP + Pi more stable than ATP n ATP4-, ADP3- 6 3  3/19/24 ATP hydrolysis in a cell n Phosphate in many cases is joined to another molecule or protein not released into solution As shown in Biology 2e…..really n Increases the should be as below molecule/protein’s P free energy : more ATP ADP unstable, more reactive 7 Energy coupling ATP hydrolysis fueling membrane transport Conformational change in the pump when phosphorylated enables Na and K to move across the membrane 8 4  3/19/24 Coupled reactions n Glutamic acid is made more reactive when it is phosphorylated by ATP n Will join with ammonia to give glutamine 9 Work depends on energy (ATP) n Movement n Transport n Chemical synthesis n Think back to lecture 1 n Motor proteins – movement n Na+ and Ca2+ pumps – membrane transport n Coupled reaction – chemical synthesis ATP movie 10 5  3/19/24 ATP n To make ATP from ADP and Pi n DG = +7.3 kcal mol-1 11 ATP cycle n Remember yesterday – energy transfer n Electrons moved from food and passed onto oxygen n Energy is extracted from these electrons as they pass through various proteins and the energy is used to generate ATP n Done by ATP synthase n We’ll look at this in more detail when we cover respiration 12 6  3/19/24 ATP We use ATP in many of our experiments in the lab Commercially it costs $318 per g!! You make around the same amount of ATP in your body per day as your weight So, if you’re 85 kg you make ~85 kg of ATP a day NZ$27,000,000!!! So, could you harvest all your ATP for one day and be rich?? 13 Enzymes n Biological catalysts n Don’t change equilibria position – just the rate at which equilibria attained (this would refer to an isolated enzyme of course) n Don’t get more product, just get that product faster n Make reactions go faster 14 7  3/19/24 Enzymes n Substrate specific n Typically will only catalyse a specific reaction n Highly regulated n Enables metabolic control (as detailed in lecture 1) 15 Enzymes Enzymes lower the activation energy for a reaction 16 8