Glycolysis & Kreb’s Cycle Cellular Respiration Lecture 2

Cellular Respiration Overview Review What are the major reactants of cellular respiration? What are the major products of cellular respiration? In what organelle in eukaryotes does cellular respiration occur?

Match the following names to the structures: Mitochondrial matrix Inner membrane space Inner Membrane Outer Membrane

The first step in cellular respiration = _______________ happens in the ________________ outside the mitochondria occurs _________________________ GLYCOLYSIS CYTOPLASM with or without oxygen

Glycolysis Requires ____________to get it started. ENERGY

Evolutionary Significance Most widespread metabolic pathway ancient prokaryotes probably used glycolysis to make ATP before oxygen was present Glycolysis happens in cytoplasm Evidence: Earliest fossil bacteria present 3.5 billion years ago large amounts of oxygen not present until 2.7 billion years ago eukaryotes appeared 1 billion years after prokaryotes (Endosymbiotic theory)

SUBSTRATE LEVEL PHOSPHORYLATION = creating ATP from removing a phosphate from the substrate and adding it directly to ADP MITOCHONDRION

Redox Reactions Oxidation is loss of electrons Glucose is oxidized Reduction is gain of electrons NAD+ is reduced to NADH Used as an electron carrying molecule to store energy until later steps

Glycolysis What are the reactants? What are the products?

PYRUVIC ACID MOVES TO NEXT STEP IF THERE IS NO OXYGEN (______________) IF THERE IS OXYGEN (_____________) = ANAEROBIC = AEROBIC

Pyruvate is transported into mitochondrion and Acetyl CoA produced For each pyruvate converted into acetyl CoA 1 molecule of CO2 is released; NAD+ ---> NADH; Coenzyme A (from B vitamin)

Kreb’s Cycle = Citric Acid Cycle occurs in mitochondrial matrix OAA CITRIC ACID Reactants? Products?

Kreb’s Cycle 2 C atoms from pyruvate → exit as CO2 For each pyruvate that enters: 2 CO2 released 3 NAD+ reduced to 3 NADH; 1 FAD+ reduced to 1 FADH2 (riboflavin, B vitamin); 1 ATP molecule