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Cellular Respiration

The Mitochondria

The MitochondriaWhat

characteristics do you notice about

the mitochondria?

What features does it have?

Mitochondrial Structure

Mitochondrion vs. ChloroplastWhat do they have in common?

What appears different?

• Both have their own DNA

• Both are small like prokaryotes

• Both make energy

Why are mitochondria important?

• All cells require energy in the form of _______.

• Mitochondria are the “powerhouses” that supply that energy by performing cellular respiration

What is Cellular Respiration?• Cellular Respiration is the

process that releases energy by breaking down food molecules in the presence of oxygen.

• all eukaryotic cells*

• Takes energy from food (glucose) and turns it into a form cells can use (ATP)*.

O2CO2

Lungs

CO2 O2Bloodstream

BREATHING

CELLULAR RESPIRATION

Cell Respiration Equation

6O2 + C6H12O2 6CO2 + 6H2O + Energy*

Oxygen + Glucose Carbon Dioxide + Water + Energy

Does this equation look familiar? It should-It is the reverse of photosynthesis!

Parts of Cellular Respiration

• Cell Resp. is broken into three parts:*– 1. Glycolysis– 2. Kreb’s Cycle– 3. Electron Transport

Chain

• Each stage uses chemical energy to make ATP.

Step 1 - Glycolysis• One molecule of glucose is broken in half, producing two 3-

carbon molecules called pyruvic acid (pyruvate).– 2 ATP and 2 NADH are generated

• Occurs in ______________.Cytoplasm

Cell Respiration OverviewRespiration

StageReactants Energy

ProductsOther

ProductsNext Stop?

Glycolysis

Kreb’s Cycle

Electron Transport Chain

Cell Respiration OverviewRespiration

StageReactants Energy

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ProductsNext Stop?

Glycolysis Glucose

Kreb’s Cycle

Electron Transport Chain

Cell Respiration OverviewRespiration

StageReactants Energy

ProductsOther

ProductsNext Stop?

Glycolysis Glucose2 ATP

2 NADH

Kreb’s Cycle

Electron Transport Chain

Cell Respiration OverviewRespiration

StageReactants Energy

ProductsOther

ProductsNext Stop?

Glycolysis Glucose2 ATP

2 NADH2

Pyruvate

Kreb’s Cycle

Electron Transport Chain

Cell Respiration OverviewRespiration

StageReactants Energy

ProductsOther

ProductsNext Stop?

Glycolysis Glucose2 ATP

2 NADH2

Pyruvate

Pyruvate--> Kreb’s cycleNADH--> Electron Trans.

Chain ATP--> Cell use

Kreb’s Cycle

Electron Transport Chain

Cell Resp. – Why is it important?• Cells require energy

(ATP) to function

• Glucose holds energy, but it must be “released” and converted to ATP for cells to use

• Cellular respiration is the conversion of glucose to ATP

Glycolysis – Why is it important?• Glycolysis is the first

step in converting glucose to ATP

• Glucose is split up into two molecules of pyruvate– It takes 2 ATP to do this

Glycolysis • From glycolysis we get:– 2 molecules of ATP for

instant use*

– 2 molecules of NADH for ETC use

• NADH holds high energy e-*

– 2 molecules of pyruvate produce *

Advantages

Fast

Doesn’t requireoxygen

Disadvantages

Cell’s NAD+ gets used up so quickly,

glycolysis can’t go on for long

Doesn’t make all that much ATP

After Glycolysis…

Glycolysis

Fermentation

Alcoholic Fermentation

Lactic Acid Fermentation

Kreb’s CycleElectron

Transport Chain

Oxygen present

No oxygen present

Two Choices:

(Respiration)

Fermentation = No ATP

Respiration = Lots of ATP

Fermentation

• When no oxygen is present, glycolysis is followed by fermentation rather than the Kreb’s cycle

• Fermentation creates more electon carries (NAD+) so that glycolysis can make more ATP*

Fermentation

• Fermentation converts NADH to NAD+– Frees up NAD+ so

glycolysis can continue and make more ATP

• Fermentation is anaerobic*– Does not require

oxygen*

Types of Fermentation

• Alcoholic Fermentation (yeast* & bacteria)– Used to make cheese, bread, wine, buttermilk, etc..

Pyruvate + NADH alcohol + CO2 + NAD+*

Types of Fermentation• Lactic Acid Fermentation (bacterial & muscle cells,

– When muscles don’t get enough oxygen, lactic acid fermentation occurs

– Build up of lactic acid makes muscles sore

*pyruvate + NADH lactic acid + NAD+

The Rest of Cell Respiration

• If oxygen is present, the cell performs cellular respiration

• After glycolysis, 90% of the energy from glucose is still unused

• Final two steps in cell respiration extract that energy using oxygen– AEROBIC processes = require oxygen

Step 2 - The Kreb’s Cycle• Summary:

– During the Kreb’s cycle, pyruvate is broken down into CO2 + energy (NADH)*

• The Kreb’s cycle takes place in the matrix* of the mitochondria

Matrix

Kreb’s Cycle• Pyruvic acid enters the mitochondrial matrix• One carbon molecule is lost as CO2 while NAD+

NADH• Remaining two carbon molecules combine with

coenzyme A to form acetyl CoA

Kreb’s Cycle a.k.a Citric Acid Cycle

Kreb’s Cycle• Acetyl CoA is turned into CITRIC ACID.

– Kreb’s Cycle a.k.a. Citric Acid Cycle

• Citric acid is broken down and two CO2 molecules are released

• During this process, energy is released in the form of 8 NADH, 2 FADH2, and 2 ATP*

• The remaining molecule, OXALOACETIC ACID (OAA), is used to restart the cycle.

Cell Respiration OverviewRespiration

StageReactants Energy

ProductsOther

ProductsNext Stop?

Glycolysis Glucose2 ATP

2 NADH2

Pyruvate

Pyruvate--> Kreb’s cycleNADH--> Electron Trans.

Chain ATP--> Cell use

Kreb’s Cycle

Electron Transport Chain

Cell Respiration OverviewRespiration

StageReactants Energy

ProductsOther

ProductsNext Stop?

Glycolysis Glucose2 ATP

2 NADH2

Pyruvate

Pyruvate--> Kreb’s cycleNADH--> Electron Trans.

Chain ATP--> Cell use

Kreb’s Cycle 2 Pyruvate

Electron Transport Chain

Cell Respiration OverviewRespiration

StageReactants Energy

ProductsOther

ProductsNext Stop?

Glycolysis Glucose2 ATP

2 NADH2

Pyruvate

Pyruvate--> Kreb’s cycleNADH--> Electron Trans.

Chain ATP--> Cell use

Kreb’s Cycle 2 Pyruvate

2 ATP8 NADH2 FADH2

Electron Transport Chain

Cell Respiration OverviewRespiration

StageReactants Energy

ProductsOther

ProductsNext Stop?

Glycolysis Glucose2 ATP

2 NADH2

Pyruvate

Pyruvate--> Kreb’s cycleNADH--> Electron Trans.

Chain ATP--> Cell use

Kreb’s Cycle 2 Pyruvate

2 ATP8 NADH2 FADH2

6CO2 (waste)

OAA

Electron Transport Chain

Cell Respiration OverviewRespiration

StageReactants Energy

ProductsOther

ProductsNext Stop?

Kreb’s Cycle2

Pyruvate

2 ATP

8 NADH

2 FADH2

6 CO2 (waste)

OAA

CO2 --> breath

NADH & FADH2--> ETC

OAA --> restart Kreb’s

ATP--> cell use

Electron Transport Chain

Krebs Results

• From all this we got 3 different forms of energy:

1. ATP – immediate cell usage

2. NADH

3. FADH2

Electron carriers that will bring high-energy

electrons to ETC

Step 3 – Electron Transport Chain

What did the ETC do in photo-

synthesis?

Step 3 – Electron Transport Chain (ETC)• The electron transport chain uses high-energy

electrons from the Kreb’s cycle to make ATP• Occurs in ____________________.*Cristae (inner membrane)

Cristae (inner membrane)

Electron Transport Chain• Electrons from NADH and FADH2 are

transported to the ETC*

• At the end of the ETC sits oxygen*, which is very electronegative (it draws electrons near it) - this causes the electrons to travel down the ETC towards oxygen– Oxygen is the terminal electron acceptor

• At the end of the chain, a protein combines the electrons with H+ and O- to make H2O*

Electron Transport Chain• Every time 2 electrons move down the ETC, their

energy pumps H+ ions into the inner membrane space, creating a concentration gradient*

• The H+ ions then want to diffuse from the inner membrane space back to the matrix*

Meanwhile…

Electron Transport Chain• To cross the

membrane, H+ moves through ATP synthase molecules making a gradient with the H+ *– Each time they do, it

creates ATP – Chemiosmosis*

• Each pair of electrons yields 3 ATP molecules

Cell Respiration OverviewRespiration

StageReactants Energy

ProductsOther

ProductsNext Stop?

Glycolysis Glucose2 ATP

2 NADH2

Pyruvate

Pyruvate--> Kreb’s cycleNADH--> Electron Trans.

Chain ATP--> Cell use

Kreb’s Cycle 2 Pyruvate

2 ATP8 NADH2FADH2

6 CO2 (waste)

OAA

CO2 --> breath

NADH & FADH2--> Electron Trans. ChainOAA --> restart Kreb’s

ATP--> cell use

Electron Transport Chain

Cell Respiration OverviewRespiration

StageReactants Energy

ProductsOther

ProductsNext Stop?

Glycolysis Glucose2 ATP

2 NADH2

Pyruvate

Pyruvate--> Kreb’s cycleNADH--> Electron Trans.

Chain ATP--> Cell use

Kreb’s Cycle 2 Pyruvate

2 ATP8 NADH2 FADH2

6 CO2 (waste)

OAA

CO2 --> breath

NADH & FADH2--> Electron Trans. ChainOAA --> restart Kreb’s

ATP--> cell use

Electron Transport Chain

NADHFADH2

Cell Respiration OverviewRespiration

StageReactants Energy

ProductsOther

ProductsNext Stop?

Glycolysis Glucose2 ATP

2 NADH2

Pyruvate

Pyruvate--> Kreb’s cycleNADH--> Electron Trans.

Chain ATP--> Cell use

Kreb’s Cycle 2 Pyruvate

2 ATP8 NADH2 FADH2

6 CO2 (waste)

OAA

CO2 --> breath

NADH & FADH2--> Electron Trans. ChainOAA --> restart Kreb’s

ATP--> cell use

Electron Transport Chain

NADHFADH2

32 ATP

Cell Respiration OverviewRespiration

StageReactants Energy

ProductsOther

ProductsNext Stop?

Glycolysis Glucose2 ATP

2 NADH2

Pyruvate

Pyruvate--> Kreb’s cycleNADH--> Electron Trans.

Chain ATP--> Cell use

Kreb’s Cycle 2 Pyruvate

2 ATP8 NADH2 FADH2

6 CO2 (waste)

OAA

CO2 --> breath

NADH & FADH2--> Electron Trans. ChainOAA --> restart Kreb’s

ATP--> cell use

Electron Transport Chain

NADHFADH2

32 ATP H20

Cell Respiration OverviewRespiration

StageReactants Energy

ProductsOther

ProductsNext Stop?

Glycolysis Glucose2 ATP

2 NADH2

Pyruvate

Pyruvate--> Kreb’s cycleNADH--> Electron Trans.

Chain ATP--> Cell use

Kreb’s Cycle 2 Pyruvate

2 ATP8 NADH2 FADH2

6 CO2 (waste)

OAA

CO2 --> breath

NADH & FADH2--> Electron Trans. ChainOAA --> restart Kreb’s

ATP--> cell use

Electron Transport Chain

NADHFADH2

32 ATP H20

ATP--> Cell useH20-->

NAD+ & FAD+ --> recycled

The Totals

Glycolysis ? ATP

Kreb’s Cycle &Electron Transport ?? ATP

_______

Total ?? ATP

The Totals

Glycolysis 2 ATP

Kreb’s Cycle &Electron Transport ?? ATP

_______

Total ?? ATP

The Totals

Glycolysis 2 ATP

Kreb’s Cycle &Electron Transport 34 ATP

_______

Total ?? ATP

The Totals

Glycolysis 2 ATP

Kreb’s Cycle &Electron Transport 34 ATP

_______

Total 36 ATP

Think about it…

• What types of cells can perform cellular respiration:– Animal cells?– Plant cells?– Bacterial cells?– Yeast cells?– Anything else you can think of?

Think about this one…

• In what situations would a cell perform fermentation over respiration? Explain.

Think About This One!

• Why might you lose weight (a lot of weight) if your mitochondria suddenly lost the ability to couple electron transport to the production of ATP?

Comparison of Fermentation to Cellular Respiration

Lactic Acid Alcoholic Cellular respirationglucose

glycolysis (pyruvic acid)

lactic acid

2 ATP

glucose glucose

glycolysis (pyruvic acid) glycolysis (pyruvic acid)

carbon dioxide

alcohol

2 ATP 36 ATP

water

carbon dioxide

Cellular Respiration vs. Fermentation

How Do Other Food Molecules Enter Metabolism?• Fat, carbohydrates and proteins enter the

cellular respiration pathway at different points

• The most likely point is at acetyl CoA

• Overall Cell Respiration