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Cellular Respiration
Ms. LowrieBiology 11
Energy Transformation
Chemical energy in food converted into energy that cells can use Glucose to ATP
Occurs in plants and animals
Figure 3 (pg 60)
Cellular Respiration
Photosynthesis
Light energy
Carbondioxide
Water Glucose Oxygen Water
Compare the Equations
Glucose Oxygen Carbondioxide
EnergyWater
+
Photosynthesis
Cellular Respiration
Sunlight
Heat
PhotosynthesisCellular
respiration
The Exchange of Chemicals
Note: Products from one process are reactants for the other.
Breathing
Lungs
Musclecells
Cellularrespiration
Cellular Respiration & Breathing
Breathing Exchanges these
gases between blood and outside air
Cellular respiration Requires cells to
exchange gases with surroundings
Remember …
Why does energy need to be transferred from glucose to ATP?
Glucose has TOO much energy Therefore, unusable
ATP – usable energy for cell
Water
Cellular Respiration
Summary Equation
Glucose Oxygen Carbondioxide
EnergyWater
+
Three Steps
1. Glycolysis Occurs in cytoplasm
2. Kreb’s cycle3. Electron transport
system
Can occur with oxygen (aerobic) or without oxygen (anaerobic)
Occurs in mitochondria
Cytoplasm(cytosol) Mitochondrion
GlycolysisKrebsCycle
ElectronTransport
Step 1 – Glycolysis
Location: Cytoplasm
Does NOT require oxygen Anaerobic phase
Plants -> Bacteria -> Humans!
Glycolysis
Glucose is broken down into 2 PGAL Uses 2 ATP molecules
Each PGAL is converted into pyruvate
a.k.a. pyruvic acid
glucose
PGAL
PGAL
pyruvate
pyruvate
Glycolysis – Glucose Breakdown
Glycolysis
2 NAD+ (hydrogen carrier) gain hydrogen & electrons Creates 2 NADH
4 ATP are produced 2 ATP replace those used to initiate Net gain of 2 ATP molecules
Glucose
2 Pyruvic acid
Cytoplasm
NADH
Glycolysis
Glucose2
Pyruvate
Kreb’s Cycle & Electron Transport System
Location: Mitochondria
DO require oxygen Aerobic
Step 2 – Kreb’s Cycle (Citric Acid Cycle)
CoA
1
2
3Pyruvic
acid
Aceticacid
Coenzyme A
Acetyl-CoA(acetyl-coenzyme A)
CO2
Pyruvate changed into usable form Acetyl coenzyme A (coA)
Kreb’s Cycle
Acetyl-coA goes through a series of reactions with water Uses water from atmosphere
Then enters Kreb’s Cycle Glucose (C6H12O6) finishes breaking
down
Carbon & Oxygen create CO2
Which is released to atmosphere
Hydrogen & electrons Picked up by NAD+ or FAD (hydrogen
receptors) to form NADH or FADH2
Net gain is 2 ATP 1 from each pyruvate
Kreb’s Cycle
Input
Acetyl coA
ADP
3 NAD
FAD
KrebsCycle
Output
3 CO2
Cycle Repeats Twice
Cytoplasm
Mitochondria
NADH NADH & FADH2
Glycolysis
Glucose2
PyruvateKrebsCycle
2 Acetyl coA
Step 3 – Electron Transport System
Uses hydrogen from NADH & FADH2
Hydrogen (and its electrons) are passed down a “stairway” of reactions Energy is released with each step
Oxygen = final hydrogen electron acceptor “Catches” hydrogen Combines with two hydrogen Forms water
Net gain is 34 ATP
Electron Transport System
ElectronStairway
Hydrogen electrons “falling”
Creates energy at each step
1/2
(from food via NADH)
2 H 2 e
Energy forsynthesis
of
Electro
n tran
spo
rt chain 2 e
2 H1/2
Cytoplasm
Mitochondria
NADH NADH & FADH2
Glycolysis
Glucose2
PyruvateKrebsCycle
ElectronTransport
2 Acetyl coA
Adding Up Aerobic ATP
Glycolysis 2 ATP
Kreb’s + 2 ATP
Electron Transport + 34 ATP 38 ATP
Adding Up Aerobic ATP
Cytoplasm
Mitochondria
Glycolysis
Glucose2
Pyruvate
2Acetyl-
CoA
KrebsCycle Electron
Transport
Maximumper
glucose:
Glucose Oxygen Carbondioxide
Water Energy
Summary Equation
Water
+
Glucose Oxygen Water Energy
Balanced Equation – Note Water
Task – Electron Transport System
Use notes & pages 62 & 63
Answer: #3, 4
(page 64)
#3 – Electron Transport System
Series of hydrogen (electron) acceptors As hydrogen moves, energy is released
What if energy from glucose was released all at once? Too quick Cause cell damage
#4 – Energy in Electron Transport
Results in: 34 ATP Water
The process of mitochondria breaking down glucose to produce ATP is …
a) Photosynthesis
b) Cellular respiration
c) Glycolysis
d) Calvin cycle
The stages, in order, of cellular respiration are …
a) Carbon fixation, Calvin cycle, Citric acid cycle
b) Light reactions, Kreb’s cycle, Electron transport system
c) Glycolysis, Kreb’s cycle, Electron transport system
d) Citric acid cycle, Glycolysis, Electron transport system
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