ellular Respiration Stage 1: Glycolysis A 007-008 Biology What s the point? The point is to make! A 007-008 Biology And how do we do that? synthase set up a + gradient allow + to flow through synthase powers bonding of i to + + + + + + + + + i + A Biology + 1
Glycolysis Breaking down glyco lysis (splitting sugar) pyruvate 6 x 3 In the cytosol? Why does that make evolutionary sense? ancient pathway which harvests energy where energy transfer first evolved transfer energy from organic molecules to still is starting point for ALL cellular respiration but it s inefficient generate only for every 1 That s not enough A Biology occurs in cytosol for me! Evolutionary perspective rokaryotes first cells had no organelles Anaerobic atmosphere Enzymes of glycolysis are well-conserved life on Earth first evolved without free oxygen ( ) in atmosphere energy had to be captured from organic molecules in absence of rokaryotes that evolved glycolysis are ancestors of all modern life ALL cells still utilize glycolysis A Biology verview 10 reactions convert (6) to pyruvate (3) produces: & consumes: net yield: & DA = dihydroxyacetone phosphate A Biology G3 = glyceraldehyde-3-phosphate ----- fructose-1,6b ------- DA --- G3 --- i i pyruvate --
Glycolysis summary ENERGY INVESTMENT ENERGY AYFF NET YIELD A Biology G3 --- - endergonic invest some exergonic harvest a little & a little like $$ in the bank net yield 1st half of glycolysis (5 reactions) Glucose priming get ready to split phosphorylate molecular rearrangement split destabilized A Biology Glucose 1 hexokinase Glucose 6-phosphate phospho isomerase Fructose 6-phosphate 3 phosphofructokinase Fructose 1,6-bisphosphate,5 aldolase isomerase Dihydroxyacetone phosphate Glyceraldehyde 3 -phosphate (G3) 6 i i glyceraldehyde 3-phosphate dehydrogenase 1,3-Bisphosphoglycerate 1,3-Bisphosphoglycerate (BG) (BG) nd half of glycolysis (5 reactions) Energy arvest production G3 donates oxidizes the sugar reduces production G3 pyruvate E sugar donates substrate level phosphorylation Finally some A Biology! 3-hosphoglycerate (3G) -hosphoglycerate (G) 7 phosphoglycerate kinase 8 phosphoglyceromutase 9 enolase hosphoenolpyruvate (E) DA --- yruvate i 6 10 pyruvate kinase G3 --- i 3-hosphoglycerate (3G) -hosphoglycerate (G) hosphoenolpyruvate (E) yruvate - - - - 3 3
Substrate-level hosphorylation In the last steps of glycolysis, where did the come from to make? the sugar substrate (E) is transferred from E to kinase 9 enolase hosphoenolpyruvate (E) yruvate 10 pyruvate kinase hosphoenolpyruvate (E) yruvate - - 3 A Biology The i came directly from the substrate! Energy accounting of glycolysis pyruvate 6 x 3 Net gain = + some energy investment (- ) small energy return ( + ) A Biology 1 6 sugar 3 sugars All that work! And that s all I get? But has so much more to give! Is that all there is? Not a lot of energy for 1 billon years + this is how life on Earth survived no = slow growth, slow reproduction only harvest 3.5% of energy stored in more carbons to strip off = more energy to harvest pyruvate 6 x 3 A Biology
What s the point? The point is to make! A 007-008 Biology And how do we do that? synthase set up a + gradient allow + to flow through synthase powers bonding of i to + + + + + + + + + i + But ave we done that yet? A Biology + 5