Essential Elements of Biochemistry BCHM 3050 Dr Srikripa Chandrasekaran Lecture 4 3 15 Notes Introduction to Glycolysis I II III IV V VI Overview of cellular respiration A Kreb s Cycle Citric Acid Cycle B Glycolysis is a set of 10 reactions C D In the first step of glycolysis 2 ATP are harvested E NADH is like our stokes F The amount of ATP that we are going to get out of NADH will increase In glycolysis glucose becomes 2 pyruvate as glycolysis progresses G NADH is an investment to obtain more energy Glycolysis A Parnas survived the WWII and was put in prison because he was believed to be a spy B Without Parnas glycolysis would not have been discovered Glycolysis proceeds through a series of 10 reactions A The first 5 reactions are referred to as the energy investment phase B Our body invests or wastes energy in the first 5 reactions C After we invest 2 ATP in the first 5 reactions we get back 4 ATP D Start with 1 molecule of glucose and end with 2 molecules of pyruvate E Glucose has 6 carbons atoms pyruvate has 3 carbon atoms F Memorize the structure of glucose Step 1 A Hexokinase is the enzyme in this part of glycolysis B When hexokinase meets glucose it is committing glucose to go through glycolysis If the free energy is negative the reaction is exothermic C D Exothermic reactions are spontaneous and irreversible cannot get glucose back easily with the same enzyme irreversible so you only show 1 arrow If the free energy is positive the reaction is endothermic E F Excess glucose is stored in the body for later use Step 2 A Glucose 6 phosphate isomerizes Step 3 A This 3rd reaction is another energy investment phase B The enzyme for this reaction is phophofructokinase1 C Bis prefix is used when you have 2 phosphate groups on different D Di prefix is used when you have 2 phosphate groups on the same carbon atoms carbon atom 1 E If you have too much ATP like if you eat a huge meal and don t work out that day then this large amount of ATP can inhibit glycolysis F When ATP is functioning as an inhibitor it binds to a different site Step 4 A Aldolase belongs to the class of enzymes called lyase because it breaks down the 6 carbon compound B Ligase enzymes put things together C This reaction is not exothermic Step 5 A Start with 1 molecule of glucose Step 6 A Reaction 6 signifies the end of the energy investing and the beginning VII VIII IX B Generation of the reducing agent NADH 2 molecules of NADH of the energy pay back generated C When NADH accepts a hydrogen it gets reduced to NADH D NADH is an electron carrier that electron will go a long way in helping us make energy later E When you have a reduction reaction you also have an oxidation F This is a redox reaction G Enzyme glyceraldehyde 3 phosphate dehydrogenase H Oxidation phosphorylation occurs on the reaction arrow of this reaction reaction 6 I Glyceraldehyde 3 phosphate is being oxidized Step 7 A First ATP generation in glycolysis via Substrate Level Phosphorylation where we make ATP sitting on an enzyme B Makes 2 molecules of ATP because the reaction occurs twice C This is a reversible reaction Step 8 A 3 converted to 2 position seems like a simple move from carbon 3 to carbon 2 but it involves an intermediate 2 3 bisphosphoglycerate X XI XII XIII B Enzyme phosphoglycerate mutase Step 9 A Dehydration reaction losing water Step 10 A Enzyme pyruvate kinase B Very energetically favorable C deltaG is very negative 2
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