BIO 13B

Carbon Metabolism I

Session Information

  • Recording: Session will be recorded via UD Capture

  • Music Today: Mood Booster playlist

  • Social Media: Paramecium Parlor @AmoebaSisters

Agenda for Today

  • Final Exam Information

  • Learning Objectives (LOs)

  • Review

  • Active Learning

  • Reminders

Final Exam Information

  • Date and Time: Thursday, 12/11 from 4:30-6:30PM in Smith 120. No alternative times available!

  • DSS Schedules: If you take your exam at DSS, schedule this yesterday.

  • Exam Format:

    • 50 questions, representing 15% of your final grade

    • Breakdown:

    • 27 questions on Thermodynamics, Respiration, Photosynthesis

    • 10 questions on Cells to Proteins

    • 11 questions on Translation to Pedigrees

    • 1 short answer question - creative thought - easy

  • Public Exam Posted in the Final Exam Module

  • Duration: 2 hours of time in class on Canvas. Bring your charged device!

  • Notesheet: One page, handwritten front and back.

Help Opportunities

  • Reading Day Office Hours: Wednesday 12/10 from 11-3 pm in Wolf 318. Come for as little or as much time as you like!

  • Free ISLL Tutoring Center - Info provided via link

  • Regular Office Hours Available!

Learning Objectives

By the end of class, students should be able to:

  • Compare and contrast oxidation and reduction reactions

  • Describe the different phases of glycolysis, including start and end products

  • Describe the start and end products of the citric acid cycle and their cellular locations

  • Identify how NADH and FADH2 from glycolysis and the citric acid cycle are utilized in the Electron Transport Chain (ETC)

Pre-Class Review

Cellular Respiration Overview

  • Overall Equation: C<em>6H</em>12O<em>6+6O</em>2ightarrow6CO<em>2+6H</em>2O+ATP+extHeatC<em>6H</em>{12}O<em>6 + 6 O</em>2 ightarrow 6 CO<em>2 + 6 H</em>2O + ATP + ext{Heat}

    • Reduced Components: Reduced (gained electrons) include oxygen.

    • Oxidized Components: Oxidized (lost electrons) include glucose.

    • Mnemonic: OIL RIG - Oxidation Involves Loss, Reduction Involves Gain (of electrons).

  • Key Insight: Follow the hydrogens! Understanding where electrons flow is crucial in cellular respiration.

Glycolysis Review

  • Key Points:

    • What goes in?

    • Starts with one molecule of glucose (6 carbons)

    • ATP involvement: How many molecules of ATP are utilized?

    • What comes out?

    • End product is 2 pyruvate (3 carbons each)

    • ATP production: How many molecules of ATP are generated?

    • NADH production: How many molecules are produced?

  • Specific Outputs:

    • 2 glucose molecules (6 carbons), yielding 2 pyruvate (3 carbons), 4 ATP produced (2 net), and 2 NADH produced.

Pyruvate Processing

  • Observations Needed:

    • What molecules are produced during pyruvate processing?

    • Location: Where do these reactions occur within the cell?

  • Key Concept:

    • For one molecule of glucose, how many molecules of Acetyl-CoA are produced?

    • 1 glucose gives 2 pyruvate, leading to 2 Acetyl-CoA upon processing.

  • Electron Transfer:

    • If pyruvate is oxidized, which molecule is reduced? Options:

    • CO2

    • NAD+

    • H+

Citric Acid Cycle (Krebs Cycle)

  • Cycle Properties:

    • Where does this cycle start?

    • Location of Acetyl-CoA: Where in the cell does this take place?

    • Production counts per cycle:

    • ATP: 1

    • NADH: 3

    • FADH2: 1

    • CO2: 2

  • Overall Yield from Glucose Processing:

    • For one molecule of glucose:

    • ATP (net): 4 (2 from glycolysis, 2 from the citric acid cycle)

    • NADH: 10

    • FADH2: 2

    • CO2: 6

  • Key Note: Same number of carbons as we started with; reflects the conservation of matter in biological processes.

Energy Considerations

  • Potential Energy Comparison:

    • What has more potential energy:

    • One molecule of ATP or one molecule of glucose?

  • ATP Production Conditions:

    • What processes are necessary before ATP can be synthesized?

    • Electron transfer and the creation of an electrochemical gradient (secondary active transport).

Electron Transport Chain (ETC)

  • Complexes Overview:

    • Complex I: Main transporter

    • Active transport takes electrons from NADH and H+

    • Electrons flow through the complex, ultimately resulting in the formation of 2 H2O and production of ATP.

Key Reactions in ETC

  • Examples of Redox Reactions:

    • NADH → NAD+ + 2e¯ + H+ (Oxidation)

    • FADH2 → FAD + 2e¯ + 2H+ (Oxidation)

  • Coenzyme Q (CoQ) Reaction:

    • CoQ+2e−+2H+<br>ightarrowCoQH2CoQ + 2e- + 2H^+ <br>ightarrow CoQH_2

    • Classify as oxidation or reduction based on electron acceptance.

ATP Synthase

  • Structure and Function:

    • A large protein complex spanning the membrane.

    • Protons (H+) flow down the electrochemical gradient through ATP synthase.

    • The movement causes a rotating part of the synthase to squeeze phosphate (PO42−PO_4^{2-}) onto ADP, regenerating ATP.

Summary of Respiration Stages

  • Table Completion Task:

    • For each phase of cellular respiration, determine:

    • Location within the cell

    • Major reactants

    • Major products

    • ATP generated (if any)

    • Molecule counts for NADH, FADH2, and CO2.

  • Key Observations:

    • Increased rate of CO2 production indicates a faster rate of citric acid cycle.

  • Experiment noted: Potassium cyanide (KCN) effects oxygen consumption in rat cells; Hypothesis supported: Cyanide inhibits the electron transport chain.