kreb cycle

Casual Interactions

  • Brief conversations about personal interests and preferences.

    • Music preferences:

    • Mention of disliking metal and country music.

Class Logistics

  • Important reminders for students:

    • Graph paper pickup:

    • Reminder that each student must leave five sheets for a post-lab assignment.

    • Sheets available at the front of the class.

    • Seminar announcement:

    • Seminar scheduled for today at 12:30 p.m. in Magruder 2001.

    • Focus on experiences of past Truman students about graduate programs at Mizzou.

    • Discussion topics include how Truman prepared students for graduate school.

    • Includes a meet and greet session with free pizza.

      • Not mandatory but attractive to students.

    • Emphasizes the importance of attending for those interested in graduate studies in life sciences.

Exam Preparations

  • Introduction of review session planned for next week's exam:

    • Request for hands raised for interest in a review session.

    • Discussion on potential dates and times:

    • Confirmed scheduling through student feedback on availability.

    • Specific time inquiries and responses:

      • Next Monday, 6-7 PM: 6 students can't attend.

      • Next Monday, 7-8 PM: 8 students can't attend.

      • Tuesday, 6-7 PM: Too many can't attend.

      • Tuesday, 7-8 PM: Too many can't attend.

    • Finalized the review session schedule to accommodate maximum attendance.

  • Review materials are to cover content up to chapter seven, including recent lessons.

Cellular Respiration Overview

  • First Step in Cellular Respiration: Glycolysis

    • Main Reaction:

    • Starting molecule: 1 glucose.

    • Main products of glycolysis:

      • 2 molecules of pyruvate.

      • 2 molecules of NADH (electron carrier).

      • Net production of 2 ATP.

    • Pyruvate further oxidized to acetyl CoA:

      • Each pyruvate produces 1 acetyl CoA and releases 1 molecule of carbon dioxide.

      • Additional production of 2 NADH from this step.

    • Net yield from glycolysis and pyruvate processing:

    • 2 ATP, 2 NADH, 2 pyruvate.

Krebs Cycle Introduction

  • Transition to discussing the Krebs Cycle (also known as):

    • Citric Acid Cycle.

    • TCA Cycle (tricarboxylic acid cycle).

    • Historical significance of names:

    • Krebs Cycle named after Sir Hans Adolf Krebs, who discovered it.

    • Other names reflect the chemistry involved.

    • Importance of understanding these interchangeable terms for exams.

Krebs Cycle Details

  • Acetyl CoA Oxidation:

    • Each acetyl CoA (with 2 carbon atoms) is fully oxidized, producing:

    • 4 molecules of carbon dioxide (CO2).

    • Reduction of NAD+ to NADH:

    • Electrons released during oxidation are transferred to NAD+, reducing it to NADH.

    • Introduction of FADH2, another electron carrier, similar to NADH but slightly different.

  • Importance of maintaining a supply of NAD+ and FAD for reactions to continue:

    • Lack of these substrates halts the Krebs cycle, leading to the necessity of fermentation in some scenarios.

Energy Production in the Krebs Cycle

  • Each cycle through the Krebs process yields:

    • 1 ATP (via phosphorylation).

    • 3 NADH.

    • 1 FADH2.

  • These products contribute to the electron transport chain, crucial for energy transition processes.

Stoichiometry of Krebs Cycle

  • Balancing the overall reaction as it relates to the Krebs cycle and glycolysis:

    • 1 glucose ultimately results in:

    • 2 pyruvate sufficient for the production of 2 acetyl CoAs.

    • 6 NADH (from glycolysis and Krebs cycle combined).

    • 2 FADH2.

    • 2 ATP.

    • CO2 production as a waste product; irretrievable energy from CO2.

    • Potential energy still available in NADH and FADH2.

Electron Transport Chain (ETC)

  • Role of the ETC in obtaining energy from the Krebs cycle products:

    • NADH and FADH2 carry high-potential energy electrons to the ETC.

    • Oxygen serves as the final electron acceptor, crucial for respiration.

  • Resulting reaction facilitates the conversion of electrons into water (H2O) and releases significant energy:

    • Carbon dioxide has been fully oxidized, leaving no more carbon in the cycle.

Conclusion of the Lecture

  • Recap of cellular respiration's integrated processes, with a focus on Krebs Cycle and its outputs leading to ATP production and waste purification through the kidneys via urine.

  • Mention of future lectures regarding the introduction of the electron transport chain, intended for exploration post-seminar.