Honors Biology - Cellular Respiration
Transcript of Honors Biology - Cellular Respiration
Regents Biology 2009-2010
Cellular RespirationHarvesting Chemical Energy
ATP
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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
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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)
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ATP
What is energy in biology?
Whoa! HOT stuff!
Adenosine TriPhosphate
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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
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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!
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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
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Cellular respiration
2 ATP 2 ATP ~34ATP+ +
~38 ATP
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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
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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!