Untitled Flashcards Set

Cellular Respiration

•  Balanced chemical equation: 

  •  C₆H₁₂O₆ + 6O2  → 6H2O + 6CO2 + energy 

• What type of organisms use CR? 

  • eukaryotic & complex organisms that live in an aerobic environment

• What is the purpose of CR? 

  • Use the breakdown of glucose (exergonic) to power ATP synthesis

• What is being oxidized and reduced (big picture)? 

  • Glucose is oxidized into 6CO2 and Oxygen is reduced to make 6H2O

• What are the role of electron carriers in CR? 

  • To  transfer electrons between glucose and oxygen

• Is this process endergonic or exergonic?  Why? 

  • Exergonic, the process of transferring electrons, breaking down glucose & ATP release energy

• Know the goal, location, reactants and products for each step within CR

Glycolysis

• Goal, Reactants and Products -

  •  Goal: Start oxidation of glucose, 

  • Reactants: 1 glucose + 2 NAD⁺ + 2 ADP

  •  Products: 2 pyruvate 2 NADH, 2 ATP

• Where does this occur in the cell? 

  • cytoplasm

• Energy investment vs energy payoff phase

  • How many ATP are used and made in each of these processes?

    •  2 ATP used and 4 ATP made

  • Energy Investment: Use two ATP to make the glucose unstable

  • Energy Payoff: Use substrate-level phosphorylation to create four ATP (net 2)

• What type of organisms use glycolysis? 

  • Universal to all organisms

    • Important & ancient

• How is ATP made during glycolysis?  Be able to explain the mechanism.

  •  Substrate level phosphorylation: The enzyme removes a phosphate group from the substrate, and gives it to ADP, phosphorylating it and creating ATP 

• Is this process endergonic or exergonic?  Why? 

  • SLP: Endergonic, builds ATP by adding a phosphate group and ADP

  • Glycolysis: Exergonic, as it breaks down glucose into 2 pyruvate and creates 2 ATP in the process. 

• What electron carrier is being used?  Is it oxidized or reduced? 

  • 2 NAD⁺ is being reduced to NADH

Pyruvate Oxidation

• Goal, Reactants, and products  

  • Goal: continue oxidation of glucose

  • Reactants: 2 pyruvate + 2 NAD⁺ 

  • Products: 2 acetyl CoA + 2 NADH + 2CO₂

• Where does this occur in the cell? 

       o    mitochondrial matrix 

• What is being oxidized?  What is being reduced? 

       o    pyruvate is being oxidized into acetyl CoA 

       o    2 NAD⁺ is being reduced into 2 NADH

• What electron carrier is being used? Is it oxidized or reduced? 

       o    NAD⁺ it is being reduced

• Know the three steps used to convert pyruvate into acetyl CoA - 

       1. A CO₂ is removed from each pyruvate

       2. NAD⁺ reduced to 2 NADH 

       3. attach Coenzyme A (CoA) to acetyl -coenzyme = activator - added to make molecule unstable

Krebs Cycle

• Goal, Reactants and Products 

       Goal: finish oxidizing glucose 

       Reactants: 2 acetyl CoA + 6 NAD⁺ + 2 FAD + 2 ADP 

       products: 4 CO₂ + 6 NADH + 2 FADH + 2 ATP

• Where does this occur in the cell? 

       o    matrix

• What is being oxidized?  What is being reduced? 

       o    2 Acetyl CoA is oxidized into 4 CO₂ 

       o    6 NAD⁺ is being reduced into 6 NADH and 2 FAD is reduced FADH2

• Which electron carriers are being used?  Are they being oxidized or reduced? 

       o    NAD⁺ and FAD. They are being reduced

• Is this process endergonic or exergonic?  Why? 

       o    Exergonic as it releases energy through electron carriers

• Be able to describe how ATP is made during the Krebs 

        o    2 ADP uses SLP to turn into 2 ATP

The ETC

• Goal, Reactants and products 

       o    Goals: give electrons to oxygen to make water 

       o    Reactants: 10 NADH + 2 FADH₂ + 6O₂  

       o    Products: 10 NAD⁺ + 2 FAD + 6 H2O

• What type of reactions occur in the ETC?  

       o    A series of exergonic redox reactions

• What is the ETC made up of? 

       o    Protein Complexes

• Is this process endergonic or exergonic?  Why? 

       o    Exergonic as the electrons start with high free energy then lose this free energy as it gets closer to oxygen, which is then collected

• Where does this process occur? 

  • Inner Mitochondrial Membrane

• Are the electron carriers being oxidized or reduced? 

  • Oxidized

• What is the final electron acceptor? 

  • 6O₂

• Why does the ETC slowly send electrons down the ETC rather than give them directly to oxygen? 

  • giving electrons directly to oxygen would cause an explosion of energy which would cause some energy to not be collected

Chemiosmosis

• Goal, Reactants and products 

  • Goal: power ATP synthesis through proton gradient

• Know the flow of H ions 

  • H ions are pumped from matrix to IMM

• Be able to describe how ATP is made 

  • As the protons diffuse back into matrix it will pass through Complex IV  which powers ATP synthesis

• Be able to describe the proton gradient that occurs and how this relates to making ATP 

  • H ions are pushed into IMM and as it diffuses back into matrix it powers ATP synthesis

• What is the function of ATP synthase?  

  • to build ATP from ADP and phosphate group

• Where does the cell get the energy to build ATP?  

  • relies on energy released from ETC

• How many ATP are produced during this process? 

  • 32-34 ATP

• How is the ETC coupled to chemiosmosis? 

  • As ETC carries electrons to oxygen it powers Complexes I, II, and III to pump protons into IMM

Alternative processes

• What is the final electron acceptor?

  • In anaerobic respiration, the final electron acceptor is usually an inorganic molecule other than oxygen, such as nitrate (NO₃⁻) or sulfate (SO₄²⁻), depending on the organism.

• What is the only difference between aerobic and anaerobic respiration?

  • The key difference is the final electron acceptor. In aerobic respiration, the final electron acceptor is oxygen, while in anaerobic respiration, it is a different molecule (e.g., nitrate, sulfate, or carbon dioxide).

• What type of organisms use anaerobic respiration?

  • Anaerobic respiration is used by anaerobic organisms (e.g., anaerobic bacteria, archaea, and some eukaryotes like yeast) that live in environments without oxygen, or in situations where oxygen is unavailable.

Fermentation

4. Know the products of both types of fermentation.

   • Lactic Acid Fermentation: Produces lactic acid (lactate) and NAD+.

   • Alcoholic Fermentation: Produces ethanol and carbon dioxide (CO₂), and also regenerates NAD+.

5. Know practical applications of lactic acid and ethanol fermentation.

   • Lactic Acid Fermentation: Used in the production of yogurt, cheese, and sourdough bread. It also occurs in muscles during intense exercise (leading to muscle fatigue).

   • Ethanol Fermentation: Used in the production of alcoholic beverages (beer, wine) and bread (CO₂ causes dough to rise).

6. Know what type of organisms use each process.

   • Lactic Acid Fermentation: Used by humans, lactic acid bacteria, and some fungi.

   • Alcoholic Fermentation: Used by yeasts and some bacteria.

7. Know when lactic acid fermentation is used in humans.

   • Lactic acid fermentation is used in human muscle cells during anaerobic conditions (e.g., during intense exercise when oxygen supply is insufficient).

8. Know which one produces CO₂.

   • Alcoholic fermentation produces carbon dioxide (CO₂), which is responsible for the bubbles in beer, wine, and the rising of bread dough.

9. How does glycolysis work with fermentation?

   • Glycolysis occurs in the cytoplasm and breaks down glucose into pyruvate, producing 2 ATP and NADH. In the absence of oxygen, fermentation regenerates NAD+ (using pyruvate as an electron acceptor) so that glycolysis can continue to produce ATP in anaerobic conditions.

10. How many ATP are produced in fermentation?

    • Fermentation produces only 2 ATP per glucose molecule (all generated through glycolysis).

Short Answer Questions

1. Be able to compare and contrast substrate level phosphorylation and oxidative phosphorylation.

   • Substrate-Level Phosphorylation: Direct transfer of a phosphate group from a high-energy substrate to ADP to form ATP. It occurs during glycolysis and the Krebs cycle and produces a small amount of ATP.

   • Oxidative Phosphorylation: Involves the electron transport chain (ETC) and chemiosmosis. It generates a large amount of ATP by using energy from the proton gradient created by the ETC.

2. Be able to compare and contrast aerobic and anaerobic respiration.

   • Aerobic Respiration: Requires oxygen; produces high amounts of ATP (about 36-38 ATP per glucose); oxygen is the final electron acceptor.

   • Anaerobic Respiration: Does not require oxygen; produces less ATP (usually about 2 ATP per glucose); uses other molecules (e.g., nitrate, sulfate) as the final electron acceptor.

3. Be able to compare and contrast both types of fermentation.

   • Lactic Acid Fermentation: Produces lactic acid, regenerates NAD+. Used by humans and some bacteria. Important in dairy products and muscles during exercise.

   • Alcoholic Fermentation: Produces ethanol and CO₂, regenerates NAD+. Used by yeast in brewing and baking.

4. Be able to explain how the ETC is coupled with chemiosmosis.

   • The ETC pumps protons (H⁺) across the inner mitochondrial membrane, creating a proton gradient. The potential energy in this gradient is used by ATP synthase to drive the synthesis of ATP through chemiosmosis.

5. Be able to explain the redox reactions of the ETC.

   • In the ETC, electrons are transferred from electron carriers (NADH and FADH₂) to protein complexes. As electrons move through the chain, they lose energy, which is used to pump protons across the membrane. The electrons are eventually accepted by oxygen (in aerobic respiration), which combines with protons to form water.

6. Be able to explain the importance of cellular respiration in the context of living organisms.

   • Cellular respiration is the process by which cells extract energy from glucose (or other nutrients) to generate ATP, the primary energy currency used for cellular activities, growth, and repair.

7. Be able to fill in a table of products and reactants for each step of CR.

8. 
   Be able to discuss examples of energy coupling in CR.

   • Energy coupling is the transfer of energy from exergonic reactions to power endergonic ones. In cellular respiration, energy from the ETC (exergonic) is used to drive ATP synthesis (endergonic) through chemiosmosis.

9. Be able to explain how a proton gradient is used to build ATP in chemiosmosis.

The proton gradient created by the ETC stores potential energy. This energy is used by ATP synthase as protons flow back into the mitochondrial matrix, driving the conversion of ADP and inorganic phosphate into ATP.