AP Biology Fall 2010

 Enzymes in the cytoplasm catalyze several steps in the breakdown of a six- carbon sugar glucose into two molecules of pyruvate, a three carbon sugar  Occurs in the cytoplasm of prokaryotes and eukaryotes

 Glycolysis begins as an energy-requiring reactions: 1. Glucose is first phosphoylated, then split to form two molecules of PGAL using two ATP molecules in the beginning process  One ATP molecule primes glucose to rearrange itself by donating a phosphate group to it

 Intermediate that forms, fructose-6- phosphate, accepts phosphate group from another ATP molecule  Intermediate is split into one PGAL and one DHAP › DHAP: molecule with same number of atoms arranged a bit differently  Enzyme converts DHAP into another PGAL  Cells invest 2 ATP

2. Two PGAL molecule are ready to enter the next reaction  Glycolysis continues as energy-releasing reactions:  Two PGAL are converted to intermediates that give up a phosphate group to ADP, so 2 ATP form  Two more intermediates do the same thing  4 ATP have formed by substrate level phosphorylation

 Substrate level phosphorylation : direct transfer of a phosphate group from a substrate of a reaction to another molecule  Two PGAL give up electrons and hydrogen's to two NAD + › Becomes NADH

 4 ATP formed  2 ATP used  Net yield of glycolysis: › 2 ATP › 2 NADH  End molecule is pyruvate  NAD+ and pyruvate can enter the next stage of reactions

1. How many ATP are produced in glycolysis? 2. How many NADH are produced in glycolysis? 3. What is the net result of glycolysis? 4. What molecule does glycolysis start with and what molecule does it end with and how many of each?

1. 4 ATP are produced NADH are produced. 3. Net result is 2 ATP, 2 NADH, and 2 pyruvate. 4. Glycolysis starts with 1 molecule of glucose, and ends with 2 molecules of pyruvate.