Lecture 24 - TCA - Oxidative phosphorylation and ETC - LC2024WT1POST

Lecture Overview

• Title: Citric Acid cycle; Oxidative Phosphorylation and Electron Transport Chain

• Date: November 27, 2024

• Focus: Understanding why mitochondria are the powerhouses of the cell.

Exam Pack Details

• Course: BIOL 112

• Purpose: Fundraising for cancer research and support for individuals affected by cancer.

• Contents: Compilation of final exam type questions covering all units.

• Distribution: Begins November 29, 2024, via email and Google Docs.

• Purchase Dates: November 25 - December 6, with discounts available for club members.

• Prices: $15 general, $10 for UBC Cancer Association members.

Cellular Respiration Structure

• Stages of Cellular Respiration:

  • Glycolysis

  • Pyruvate oxidation/Acetyl-CoA synthesis

  • Citric Acid Cycle (TCA)

  • Oxidative Phosphorylation

• Purpose: Capture energy in the form of ATP.

Citric Acid Cycle Overview

• Alternate Names: Tricarboxylic Acid Cycle (TCA), Krebs Cycle.

• Historical Note: 1953 Nobel Prize awarded for the discovery of the Citric Acid Cycle and Co-enzyme A.

Cellular Locations of Citric Acid Cycle

• Eukaryotes:

  • Pyruvate processing and the Citric Acid cycle occur in mitochondria.

  • Krebs cycle in mitochondrial matrix.

• Prokaryotes (Bacteria):

  • Processes occur across cell membrane.

Key Processes in Mitochondria

• Citric Acid Cycle Events:

  • Inputs include Acetyl-CoA, and outputs include CO2, NADH, and ATP.

• Energy Carriers:

  • NAD+ reduced to NADH.

  • FAD picks up electrons becoming FADH2.

Inputs and Outputs of the Citric Acid Cycle

• Input: Acetyl-CoA

• Outputs:

  • CO2

  • NADH

  • ATP (or GTP)

  • FAD and CoA

Oxidative Phosphorylation Overview

• Definitions:

  • Involves both substrate-level phosphorylation (SLP) and oxidative phosphorylation through the electron transport chain (ETC).

  • Energy is captured through electron transport leading to ATP synthesis via proton gradient.

Steps of Oxidative Phosphorylation

1. Electrons from NADH and FADH2 are delivered to the electron transport chain.

2. Energy is used to pump protons H+ across the membrane, creating a proton gradient.

3. Protons flow through ATP synthase, leading to ATP synthesis.

ATP Synthase Functionality

• Proton Gradient:

  • High concentration of protons in the intermembrane space.

  • Protons diffuse back into the matrix through ATP synthase to synthesize ATP.

• Function of ATP Synthase:

  • Indirect synthesis of ATP through the proton motive force.

Learning Objectives for Students

• Contrast cellular locations of ETC/oxidative phosphorylation in bacterial and eukaryotic cells.

• Describe the general process of electron transport and proton gradient formation.

• Explain the chemiosmotic theory connecting the ETC and ATP synthesis.

• Understand the difference between substrate-level phosphorylation and oxidative phosphorylation.

• Predict impacts of metabolic inhibitors on ETC function.

Study Recommendations

• Review key concepts from the lecture.

• Practice problems relevant to the Citric Acid Cycle and ETC.

• Clarify any difficult topics with tutors or study groups.

• Utilize visual aids to understand the flow of processes within mitochondria.