Notice that in anaerobic conditions, the net energy gain is only 2 ATP molecules from glycolysis. The produced NADH molecules are converted back to NAD+ as 2 pyruvate molecules get converted to 2 lactate molecules (in muscles)or 2 ethanol molecules(fermentation in yeast). These reactions occur in the cytoplasm In aerobic conditions, pyruvates are further broken down in mitochondria to generate more NADHs and FADH2s through the Krebs'(citric acid)cycle. These molecules are then used to pump protons that can subsequently be used to drive ATP synthase in the inner mitochondrial membrane. the net ATP production is 34 A TPs(from Kreb's cycle and the electron transport chain)+2 ATPs(from glycolysis)=36 ATPs Chart removed due to copyright reasons. Again, there is no need to memorize the technical details. The point here is 6. Before 02 appeared in the atmosphere, only two molecules of atP were generated per molecule of glucose. Organisms utilizing this system couldn't be very fast, or big or smart. recall that life on earth first appeared more than 4 billion years ago, and eukaryotic cells appeared probably around 1.5 billion years ago, but O2 did not appear in significant amounts until about 600 million years ago. So it's the appearance of oxygen that allowed for rapid evolution and diversity found on earth 7. Final point. There is a large number of biochemical pathways that interact These interacting pathways allow the organism to take a sugar source and synthesize everything else needed. Again, many of these reactions are endergonic, so cells use ATP to facilitate them 7.012 Fall 2004 lecture 5 notes4 Notice that in anaerobic conditions, the net energy gain is only 2 ATP molecules from glycolysis. The produced NADH molecules are converted back to NAD+ as 2 pyruvate molecules get converted to 2 lactate molecules (in muscles) or 2 ethanol molecules (fermentation in yeast). These reactions occur in the cytoplasm. In aerobic conditions, pyruvates are further broken down in mitochondria to generate more NADHs and FADH2s through the Krebs’ (citric acid) cycle. These molecules are then used to pump protons that can subsequently be used to drive ATP synthase in the inner mitochondrial membrane. The net ATP production is 34 ATPs (from Kreb’s cycle and the electron transport chain) + 2 ATPs (from glycolysis) = 36 ATPs. Again, there is no need to memorize the technical details. The point here is 6. Before O2 appeared in the atmosphere, only two molecules of ATP were generated per molecule of glucose. Organisms utilizing this system couldn’t be very fast, or big, or smart. Recall that life on Earth first appeared more than 4 billion years ago, and eukaryotic cells appeared probably around 1.5 billion years ago, but O2 did not appear in significant amounts until about 600 million years ago. So it’s the appearance of oxygen that allowed for rapid evolution and diversity found on Earth. 7. Final point. There is a large number of biochemical pathways that interact. These interacting pathways allow the organism to take a sugar source and synthesize everything else needed. Again, many of these reactions are endergonic, so cells use ATP to facilitate them. 7.012 Fall 2004 lecture 5 notes Chart removed due to copyright reasons