Cellular Respiration: Supplying Energy to Metabolic · PDF fileCellular Respiration: Supplying...
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Cellular Respiration: Supplying Energy to Metabolic Reactions
Cellular Respiration
ATP powers most of the processes in a cell including:
* Muscle movement* Active Transport
ATP also provides the necessary activation energy to
* Synthesise organic compounds (endergonic, anabolic reactions)* Speed up many exergonic, catabolic reactions.
You use HEAPS of ATP. Here are some estimates
* 10 million molecules per muscle cell per second!* The average vertebrate consumes its own body weight in ATP every day!
It is important, therefore, that ATP/ADP is recyclable- like a rechargeable battery. Respiration is the metabolic
reaction that recharges ADP to ATP.
Thursday, April 29, 2010
Coenzymes
Cellular Respiration: Coenzymes
Coenzymes are relatively small organic non-protein molecules that catalyse reactions by acting as carriers of electrons and protons. They may also carry specific atoms or groups of atoms, such as phosphate, that are required for, or produced by, chemical reactions.
The coenzymes we study in VCE Biology cycle between “loaded” and “unloaded” states. The process of respiration draws on 3 of these listed molecules.
CoenzymeAbbreviationAbbreviation
FunctionCoenzymeUnloaded Loaded
Function
Adenosine Triphosphate ADP ATP Energy Transfer in many processes
Nicotinamide adenine dinucleotide phosphate NADP NADPH
Transfer of electrons and protons in photosynthesis
Nicotinamide adenine dinucleotide NAD+ NADHTransfer of electrons and protons
in respiration
Flavin adenine dinucleotide FAD FADH2Transfer of electrons and protons
in respiration
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The ATP Cycle
Cellular Respiration: The ATP Cycle
Remember this? ATP is the most important molecule for the transport of usable chemical energy in cells.
Endergonic reactions absorb energy
Anabolic reactions build molecules
Exergonic reactions release energy
Catabolic reactions break down molecules
The ATP CycleAfter it “unloads” energy its terminal phosphate group an ADP molecule can undergo a
second reaction that adds a new phosphate group and “reloads” it as ATP.
Thursday, April 29, 2010
Cellular Respiration Pathways
Cellular Respiration: Pathways
Respiration is the metabolic process by which glucose is broken down to release energy and make ATP
There are three different pathways for cellular respiration to occur. Each pathway has multiple stages.
A. Aerobic Cellular Respiration (oxygen present)1. Glycolysis 2. Krebs Cycle3. Electron Transport Chain
B. Anaerobic Respiration (oxygen absent)1. Glycolysis2. Alcohol Fermentation
C. Anaerobic Respiration (oxygen absent)1. Glycolysis2. Lactic Acid Fermentation
As you can see, glycolysis is common to all respiration pathways.
Thursday, April 29, 2010
Cellular Respiration Pathways
Cellular Respiration: Pathways
Respiration is the metabolic process by which glucose is broken down to release energy and make ATP
There are three different pathways for cellular respiration to occur. Each pathway has multiple stages.
A. Aerobic Cellular Respiration (oxygen present)1. Glycolysis 2. Krebs Cycle3. Electron Transport Chain
B. Anaerobic Respiration (oxygen absent)1. Glycolysis2. Alcohol Fermentation
C. Anaerobic Respiration (oxygen absent)1. Glycolysis2. Lactic Acid Fermentation
As you can see, glycolysis is common to all respiration pathways.
Thursday, April 29, 2010
Cellular Respiration Pathways
Cellular Respiration: Pathways
Respiration is the metabolic process by which glucose is broken down to release energy and make ATP
There are three different pathways for cellular respiration to occur. Each pathway has multiple stages.
A. Aerobic Cellular Respiration (oxygen present)1. Glycolysis 2. Krebs Cycle3. Electron Transport Chain
B. Anaerobic Respiration (oxygen absent)1. Glycolysis2. Alcohol Fermentation
C. Anaerobic Respiration (oxygen absent)1. Glycolysis2. Lactic Acid Fermentation
As you can see, glycolysis is common to all respiration pathways.
Bork Bork Bork!
Thursday, April 29, 2010
Location
Cellular Respiration: Location
The mitochondrion is the primary location for respiration. It consists of;
* A smooth outer membrane* An inner membrane whose many folds make up the cristae
* A fluid rich intermembrane space* The matrix
Do not rely too much on shape.
Mitochondria can look like a ball, jellybean or
cigar!
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1. Glycolysis Reaction
Cellular Respiration: Glycolysis
All respiration begins in the cytoplasm with glycolysis. This is a very complex 10 step reaction and you needn’t learn it all- an appreciation of the reactions is enough.
Watch and note:
* Inputs and Outputs; especially involving ATP
* The location where glycolysis occurs
* The formation of G3P and its conversion to pyruvate.
Video Link
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1. Glycolysis: Inputs and Outputs
Cellular Respiration: Glycolysis
IN OUT
Glucose
2 x
2 x 2 x
2 x Pyruvate
Know your net inputs and outputs
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The next step.....
Cellular Respiration: Pathways
Glycolysis
Krebs Cycle
Electron Transport Chain
Lactic Acid Fermentation
Alcohol Fermentation
oxygen present
oxygen absent
oxygen absent
Aerobic RespirationMost plants, animals,
protists, fungi, bacteria
Anaerobic RespirationAnimals
Anaerobic RespirationMany microorganisms
(eg. yeast, some bacteria)
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Aerobic Cellular Respiration
Cellular Respiration: Aerobic
You will be familiar with this equation from Yr 11
6H2O + 6CO2 + 386O2 + C6H12O6
This basic equation applies to aerobic respiration and you need to have memorised this.
The energy captured as ATP and sent to where it is needed elsewhere in the cell.
What does this suggest to you about cells possessing high numbers of mitochondria?
+ Glucose Water + 38 ATP+ Carbon DioxideOxygen
Thursday, April 29, 2010
2. Aerobic Respiration- Krebs Cycle (Complex)
Cellular Respiration: Aerobic
If oxygen is available, glycolysis will be followed by the Krebs Cycle (also called citric acid cycle) in the matrix.
Watch and note:
* Inputs and Outputs
* Conversion of pyruvate to Acetyl CoA prior to entering the Krebs Cycle
* The location in which the Krebs Cycle occurs
Video Link
Thursday, April 29, 2010
2. Aerobic Respiration- Krebs Cycle
Cellular Respiration: Aerobic
INPUT NET OUTPUT
6 x
2 x
Carbon Dioxide
2 x Acetyl CoA (from pyruvate)
Know the significant inputs and outputs: At this stage I have only included numbers where significant.
2 x (from glycolysis)
FAD+2 x 2 x FADH2
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3. Aerobic Respiration- Electron Transport Chain
Cellular Respiration: Aerobic
The NADPH and FADH2 produced in both glycolysis and the Krebs cycle is fed into the Electron Transport Chain. The Electron Transport produces far more ATP than the previous two stages and happens on the inner membrane.
Watch and note
* The purpose of the electron carriers in driving the proton gradient
* The purpose of oxygen and its conversion to water
* The use of the chemical gradient to drive ATP synthesis.
Thursday, April 29, 2010
3. Aerobic Respiration- Electron Transport Chain
Cellular Respiration: Aerobic
IN OUT
FADH2or
Oxygen Water
34 x
FAD+or
+
Know the significant inputs and outputs: I have only included numbers where significant.
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Aerobic Respiration- Overview
Cellular Respiration: Aerobic
DO NOT PANIC- in all likelihood knowing this diagram will be enough!
2 2 34
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Aerobic Respiration- Overview
Cellular Respiration: Aerobic
Vid
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Anaerobic Pathways: Fermentation
Cellular Respiration: Pathways
Glycolysis
Krebs Cycle
Electron Transport Chain
Lactic Acid Fermentation
Alcohol Fermentation
oxygen present
oxygen absent
oxygen absent
Aerobic RespirationMost plants, animals,
protists, fungi, bacteria
Anaerobic RespirationAnimals
Anaerobic RespirationMany microorganisms
(eg. yeast, some bacteria)
Thursday, April 29, 2010
Anaerobic Respiration: Lactic Acid & Alcohol Fermentation
Cellular Respiration: Anaerobic
C6H12O6 2CH3CH(OH)COOH + 2
C6H12O6 2CH3CH2OH + 2CO2 + 2
Glucose Lactic Acid + 2 ATP
Glucose Ethanol + 2 ATP+ Carbon Dioxide
In anaerobic respiration oxygen is not available to drive the Krebs Cycle and Electron Transport Chain.
* Instead the cell enters either a lactic acid or alcohol fermentation stage. * Essentially this pathway provides a way to metabolise the pyruvate and recycle the NADH/NAD+ that was produced by glycolysis. * Lactic acid or ethanol are the final products of glucose catabolism. Overall the only ATP produced in this reaction was from the glycolysis stage making fermentation highly inefficient.
Lactic Acid Fermentation- Animals
Alcohol Fermentation- Yeast and other Microorganisms
Remember the word equations
Thursday, April 29, 2010
Anaerobic Respiration: Lactic Acid & Alcohol Fermentation
Cellular Respiration: Anaerobic
Vid
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ere
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Cellular Respiration: Overview of all Pathways
Cellular Respiration: Overview
Thursday, April 29, 2010
Respiration and Evolution: Interesting Facts
Respiration and Evolution
Aerobic Respiration recovers about 40% of the energy in glucose- more efficient than a modern car engine.
Glycolysis recovers only about 3% of the energy stored in glucose; nevertheless for a long period much of the history of life was written by organisms that could perform only glycolysis.
Many of the most successful organisms in existence are anaerobic and thus only achieve 3% efficiency.
Nonetheless it was only after the evolution of the Krebs Cycle and Electron Transport Chain that respiration could achieve a level of efficiency capable of sustaining larger, and more complex, multicellular organisms.
Facultative bacteria are able to meet energy demands by either aerobic or anaerobic respiration.
Thursday, April 29, 2010