Chapter 9 Respiration

Title: 9-2 The Krebs Cycle & Electron

TransportEssential Question?

What happens during the Krebs Cycle and the Electron Transport Chain

What happens during the Krebs cycle?

How are high-energy electrons used by the electron transport chain?

Objective

At The End Of Glycolysis, 90% Of The Energy Is Still

Contained In The Pyruvate Molecules.

Aerobic Respiration Will Release The Energy

Overview of Respiration

Cellular Respiration Is The Process That Releases

Energy By Breaking Down Molecules Of Glucose In The

Presence Of Oxygen.

Overview of Respiration

C6H12O6 + 6O2

6CO2 + 6H2O

Cellular Respiration

In The Presence of Oxygen

Back Where We Started

Hans Krebs (1900-1981)◦ Forced to emigrate from

Germany to England in 1933.◦ Noble Prize in Physiology 1953◦ Discovered:

1. Glycolysis Happens In The Cytoplasm

2. Pyruvic Acid Then Moves To The Mitochondria

The Krebs Cycle

Mitochondria

Key Concept:

During The Krebs Cycle, Pyruvic Acid Is Broken Down Into Carbon Dioxide, In A Series Of Energy-Extracting Reactions

The Krebs Cycle

The Krebs CycleAKA

The Citric Acid Cycle

The Krebs Cycle

Step ACitric Acid Production

Pyruvic Acid (3 Carbon

Compound) Enters The Mitochondria

1 Carbon becomes CO2

2 Carbons Join Coenzyme A Forming Acetyl-CoA next◦ 2 Carbon acetyl group added

forming Citric Acid (6 Carbon)

The Krebs Cycle

Step BEnergy Extraction

Citric Acid breaks down to a 4-Carbon Molecule + 2CO2

High Energy Electrons Released◦ Electrons Captured By: NAD+ FAD (flavine adenine

dinucleotide)

The Krebs Cycle

CO2-You breath it out

ATP-Powers Cellular Activities

NADH & FADH2-Powers Electron Transport Chain

The Krebs Cycle

Key Concept:

The Electron Transport Chain In The Mitochondria Inner Membrane Uses High Energy Electrons From The Krebs Cycle To Convert ADP into ATP

Electron Transport Chain

Electron Transport Chain

Electron Transport Chain

Step A◦NADH & FADH2 Release High Energy Electrons & H+

◦Electrons Picked Up By Carrier Proteins In The Mitochondrial Inner Membrane (Eukaryotes) In The Cell Membrane of Prokaryotes

Electron Transport Chain

Step A (continued)

◦At The End Of The Electron Transport Chain The Electrons Must Be Passed To An Electron Acceptor – They Can Not Just Vanish

Where Do They Go??????

Electron Transport Chain

Step A (continued)◦ Oxygen Is The Final Electron

Acceptor. Hydrogen Ions Are Attached And Water Is Formed

This Is Why You Need To Breath In

Oxygen!

Electron Transport Chain

Step B Every Time 2 High

Energy Electrons Pass Through The Electron Transport Chain◦ H+ (Hydrogen Ions)

Are Transported Into The Mitochondrial Intermembrane Space!

Electron Transport Chain

Intermembrane Space

Matrix

Step CATP Synthase

H+ ProvidesEnergy For

ATP Production

Electron Transport Chain

Glycolysis 2 ATP

Krebs Cycle &Electron Transport 34 ATP

36 ATP

ATP = 38% Energy In 1 GlucoseHeat = 62% Energy In 1 Glucose

The Totals per Glucose

Quick Exercise◦Uses Current ATP Stores◦Cell Kicks In Lactic Acid Fermentation

◦Provides Energy Only For About 90 Seconds

Energy & Exercise

Quick Energy (continued)◦Lactic Acid Builds Up In The Cell & MUST Be Removed

◦That Requires Extra Oxygen Heavy Breathing Sore, Tired Muscles

Energy & Exercise

Long-Term Energy◦Cellular Respiration Must Accelerate Drawing Energy From:GlucoseGlycogenFats

Energy & Exercise