Regents Biology 2009-2010

Cellular RespirationHarvesting Chemical Energy

ATP

Regents Biology

CO2 + H2O + heatfuel

(carbohydrates)

O2

“Burn fuels” to make energycombustionmaking heat energy by burning fuels in one step

ATP

ATP + CO2 + H2O (+ heat)

aerobic respirationmaking ATP energy (& some heat) by burning fuels in many small steps

food(carbohydrates)

O2

Regents Biology

Energy needs of life Animals are energy consumers

What do we need energy for? synthesis (building for growth) reproduction active transport movement temperature control (making heat)

Regents Biology 2009-2010

ATP

What is energy in biology?

Whoa! HOT stuff!

Adenosine TriPhosphate

Regents Biology

Harvesting energy stored in food Cellular respiration

breaking down food to produce ATP in mitochondria using oxygen

“aerobic” respiration

usually digesting glucose but could be other sugars,

fats, or proteins

C6H12O6 6O2 ATP 6CO2 6H2O+ + +

glucose + oxygen energy + carbon + water dioxide

O2

food ATP

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What do we need to make energy? The “Furnace” for making energy

mitochondria Fuel

food: carbohydrates, fats, proteins Helpers

oxygen enzymes

Product ATP

Waste products carbon dioxide

then used by plants water

O2

food

ATP

Make ATP!Make ATP!

All I do all day…And no one

even notices!

enzymes

CO2 H2O

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Mitochondria are everywhere!!

animal cells plant cells

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Overview of cellular respiration 3 metabolic stages

Anaerobic respiration1. Glycolysis

respiration without O2

in cytosol

Aerobic respiration respiration using O2

in mitochondria

2. Krebs cycle

3. Electron transport chain

C6H12O6 6O2 ATP 6H2O 6CO2+ + + (+ heat)

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Cellular RespirationStage 1:

Glycolysis

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Glycolysis

glucose pyruvate2x6C 3C

In thecytosol?

Why doesthat make

evolutionarysense?

That’s not enoughATP for me!

Breaking down glucose “glyco – lysis” (splitting sugar)

ancient pathway which harvests energy where energy transfer first evolved transfer energy from organic molecules to ATP still is starting point for ALL cellular respiration

but it’s inefficient generate only 2 ATP for every 1 glucose

occurs in cytosol

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Glycolysis summary endergonicinvest some ATP

exergonicharvest a little ATP & a little NADH

net yield2 ATP2 NADH

4 ATP

ENERGY INVESTMENT

ENERGY PAYOFF

G3PC-C-C-P

NET YIELD

like $$in the bank

-2 ATP

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Cellular RespirationStage 2:

Krebs Cycle

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Occurs in Mitochondria

Krebs cycle produces large quantities of electron carriers NADH FADH2

go to Electron Transport Chain!

Use Pyruvate to Make Electron Carriers

What’s so important about

electron carriers?

H+

H+H+

H+

H+ H+

H+H+H+

ATP

ADP+ Pi

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Energy accounting of Krebs cycle

Net gain = 2 ATP

= 8 NADH + 2 FADH2

1 ADP 1 ATPATP

2x

4 NAD + 1 FAD 4 NADH + 1 FADH2

pyruvate CO2

3C 3x 1C

Regents Biology

Cellular RespirationStage 3:

Electron Transport Chain

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ATP accounting so far… Glycolysis 2 ATP Kreb’s cycle 2 ATP Life takes a lot of energy to run, need to

extract more energy than 4 ATP!

A working muscle recycles over 10 million ATPs per second

There’s got to be a better way!

I need a lotmore ATP!

Regents Biology

There is a better way! Electron Transport Chain

series of proteins built into inner mitochondrial membrane uses transport proteins & enzymes

transport of electrons from carriers down ETC linked to pumping of H+

yields ~36 ATP from 1 glucose! only in presence of O2 (aerobic respiration)

O2That

sounds morelike it!

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But what “pulls” the electrons down the ETC?

electronsflow downhill

to O2 oxidative phosphorylation

O2

H2O

Regents Biology

Cellular respiration

2 ATP 2 ATP ~34ATP+ +

~38 ATP

Regents Biology

make energyA Body’s Energy Budget

eatfood

synthesis(building)

• energy needed even at rest

• activity• temperature

control{

• growth• reproduction• repair{

storage• glycogen

(animal starch)• fat{

ATP1

2

3

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What if oxygen is missing? No oxygen available = can’t complete

aerobic respiration Anaerobic respiration

also known as fermentation alcohol fermentation lactic acid fermentation

no oxygen or no mitochondria (bacteria)

can only make very little ATP large animals cannot survive

O2

yeast

bacteria

Regents Biology

Anaerobic Respiration Fermentation

alcohol fermentation yeast

glucose ATP + CO2+ alcohol

make beer, wine, bread

lactic acid fermentation bacteria, animals

glucose ATP + lactic acid bacteria make yogurt animals feel muscle fatigue

O2

Tastes good…but not enoughenergy for me!