Ch. 6 Cellular Respiration 6.6 – 6.10

Redox reactions release energy when electrons fall from a hydrogen carrier to oxygen Where do all the electrons come from for the redox reactions in the cells? It comes from NADH made during the oxidation of glucose. How do electrons make it to the electron carriers? When NADH gives up electrons to electron carriers.

What keeps the electrons coming down the Electron transport chain? O2 at the bottom pulls electrons down the energy hill. What happens to the energy of the electrons as it falls down the electron transport chain? The energy is used to pump H+ against their gradient which then come back through ATP synthase to generate ATP

Two ways to make ATP. Chemiosmosis and … Do you remember what chemiosmosis is? When ATP is made by movement of Hydrogen ions from high to low concentration via the protein ATP synthase. How does a high concentration of hydrogen ions form in the first place? H+ ions are actively transported using electron energy

… Substrate-level phosphorylation. How does substrate-level phosphorylation differ from chemiosmosis? No membrane is involved (no ETC). So what does happen? An enzyme helps transfer a phosphate from a substrate (an organic molecule) to an ADP making an ATP and a new organic molecule. In which process will cells make more ATP, chemiosmosis or substrate-level phosphorylation. More ATP is made in chemiosmosis.

Respiration occurs in 3 stages: What are the first two stages of cellular respiration? Glycolysis and Krebs cycle. Where does glycolysis take place? In the cytoplasm. What happens in glycolysis? 2 pyruvic acids, 2ATP and 2NADH are made.

Overview of Krebs cycle Where does the Krebs cycle occur? In the mitochondria. What happens in the Krebs cycle? Breaking down pyruvic acid to acetyl CoA then oxidizing it to CO2 and generating ATP, NADH & FADH2 What way does glycolysis and Krebs cycle make ATP? Substrate-level phosphorylation.

Where does glycolysis and Krebs cycle take energy from? Food oxidized to CO2. How are electrons carried to the top of the electron transport chain? NAD+ and FAD (temporarily becoming NADH & FADH2) How does the Electron transport chain, the third stage of respiration, make ATP? By chemiosmosis, the movement of Hydrogen ions from high to low concentration via the protein ATP synthase

Glycolysis harvest chemical energy by oxidizing glucose to make pyruvic acid. What are all the compounds called that form between input of glucose to output of Pyruvic acid? Intermediates. Even though there are 9 reactions in glycolysis, we are only concerned with the net gain.

Glycolysis means: Splitting of Sugar What starts glycolysis? An investment of energy in the forms of glucose and 2 ATP. What happens to that investment of energy? Becomes a payoff of energy resulting in 4 ATP and 2 NADH and 2 Pyruvate. What is produced during Glycolysis? 2 Pyruvate, 2 ATP, 2 NADH, and 2 H+ and 2 H2O How is this like selling a house? Fix it up, invest to make it nice to get your payoff from selling it.

Pyruvic acid is chemically groomed for the Krebs cycle What happens inside the mitochondria to pyruvic acid? 1) It is oxidized while NAD+ is reduced to NADH, 2) carbon is released in CO2, 3) coenzyme A joins remaining 2 carbon fragment to form Acetyl CoA What is the Acetyl CoA used for? It is used as fuel for the Krebs cycle, the next step. For each molecule of glucose to enter glycolysis how many molecules of Acetyl CoA enter the Krebs cycle? Two.

Glycolysis- ch.7