essential knowledge 2.a.2: organisms capture and store free energy for use in biological processes
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Enduring Understanding: Growth, reproduction and maintenance of the organization of living systems require free energy and matter. Essential Knowledge 2.A.2: Organisms capture and store free energy for use in biological processes. - PowerPoint PPT PresentationTRANSCRIPT
Enduring Understanding: Growth, reproduction and
maintenance of the organization of living systems require free
energy and matterEssential Knowledge 2.A.2: Organisms capture
and store free energy for use in biological processes
What happens to pyruvate after glycolysis?◦ Pyruvate is transported from the cytoplasm to the
mitochondrion via a transport protein.◦ Pyruvate’s carboxyl group (COO-), which is
already fully oxidized, is removed as CO2◦ The remaining 2 carbon fragment is oxidized,
forming a 2 C compound called acetate and reducing NAD+ to NADH + H+
◦ Acetate joins with Coenzyme-A, which makes it very reactive, forming Acetyl Co-A
Cellular respiration in eukaryotes involves a series of coordinated enzyme-catalyzed reactions that harvest free energy from simple carbohydrates
CYTOSOL
MITOCHONDRION
NAD+
NADH
+ H+
2
1 3
PyruvateTransport protein
CO2
Coenzyme A
Acetyl CoA
Cellular respiration in eukaryotes involves a series of coordinated enzyme-catalyzed reactions that harvest free energy from simple carbohydrates Where does the Krebs Cycle take place?
◦ The matrix of the mitochondria When Acetyl Co-A enters the Krebs Cycle,
what does it join with?◦ It joins with OAA (oxaloacetate). The 2 carbons
originally from Pyruvate (and glucose) join with the 4 carbons of OAA to form 6 carbon Citrate.
What happens in the Krebs cycle?◦ Through a series of enzyme catalyzed reactions
the remaining 2 carbons from pyruvate (originally from glucose) are oxidized and expelled as CO2. 3 NAD+ are reduced to form 3 NADH + 3H+ and 1 FAD is reduced to form 1 FADH2. Indirectly 1 ATP is formed.
How is ATP formed during the Krebs Cycle?◦ Substrate level phosphorylation
Cellular respiration in eukaryotes involves a series of coordinated enzyme-catalyzed reactions that harvest free energy from simple carbohydrates
Acetyl CoACoA—SH
Citrate
H2O
Isocitrate NAD+
NADH+ H+
CO2
-Keto-glutarate
CoA—SH
CO2NAD+
NADH+ H+Succinyl
CoA
CoA—SH
P iGTP GDP
ADP
ATP
SuccinateFAD
FADH2
Fumarate
CitricacidcycleH2O
Malate
Oxaloacetate
NADH+H+
NAD+
1
2
3
4
5
6
7
8
Summary of products from 1 turn of the Krebs Cycle:
2 CO23NADH + H+
1FADH21ATP
Pyruvate
NAD+
NADH+ H+ Acetyl
CoA
CO2
CoA
CoA
CoA
Citricacidcycle
FADH2
FAD
CO22
3
3 NAD+
+ 3 H+
ADP +
P i
ATP
NADH
Summary of products from the end of glycolysis thru the Krebs Cycle per glucose molecule:6 CO28 NADH + H+
2 FADH22ATP
Enduring Understanding 4.A: Interactions within biological systems lead to complex properties (side bar) Essential Knowledge 4.A.2:The structure and
function of subcellular components, and their interactions, provide essential cellular processes.◦ How do mitochondria specialize in energy capture and
transformation? Mitochondria have a double membrane that allows
compartmentalization within the mitochondria and is important to its function Matrix (within the inner membrane) Intermembrane Space (between the inner & outer membranes)
The outer membrane is smooth, but the inner membrane is highly convoluted, forming folds called cristae
Cristae contain enzymes important to ATP production; cristae also increase the surface area for ATP production
Free ribosomesin the mitochondrial matrix
Intermembrane space Outer
membrane
Inner membraneCristae Matrix
0.1 µm
The electron transport chain captures free energy from electrons in a series of coupled reactions that establish an electrochemical gradient across membranes. Where is the electron transport chain of
cellular respiration?◦ The Cristae (inner member of mitochondria)◦ In prokaryotic organisms it is located in the
plasma membrane
What happens at the electron transport chain?◦ Electrons delivered by NADH and FADH2 are passed
thru a series of electron acceptors as they move toward the terminal electron acceptor, oxygen.
What happens as electrons move through the electron transport chain?◦ The energy released by passage of electrons from one
electron carrier to the next is used to pump H+ from the matrix into the intermembrane space. (In prokaryotes H+ is pumped outside the plasma membrane.)
◦ This creates a gradient of H+ across the membrane called a proton-motive force.
The electron transport chain captures free energy from electrons in a series of coupled reactions that establish an electrochemical gradient across membranes.
How does the proton gradient (H+) produce ATP?◦ The energy stored in the
proton gradient is released as H+ move back across the cristae through H+ channels provided by ATP synthases - chemiosmosis
The electron transport chain captures free energy from electrons in a series of coupled reactions that establish an electrochemical gradient across membranes.
INTERMEMBRANE SPACE
Rotor
H+
Stator
InternalrodCata-lyticknob
ADP+P ATP
iMITOCHONDRIAL MATRIX
Protein complexof electroncarriers
H+
H+H+
Cyt c
Q
V
FADH2
FADNAD
+NADH(carrying
electronsfrom food)
Electron transport chain
2 H+ + 1/2O2
H2O
ADP +
P i
Chemiosmosis
Oxidative phosphorylation
H+
H+
ATP synthase
ATP
21
The electron transport chain captures free energy from electrons in a series of coupled reactions that establish an electrochemical gradient across membranes.
Chemiosmosis couples the electron transport chain to ATP Synthesis…◦ Electron Transport Chain: Electron transport and
pumping protons (H+), which create an H+ gradient across the membrane
◦ Chemiosmosis – ATP synthesis powered by the flow of H+ back across the membrane
Maximum per glucose:
About36 or 38
ATP
+ 2 ATP
+ 2 ATP
+ about 32 or 34 ATP
Oxidativephosphorylation:
electron transport
andchemiosmosis
Citricacidcycle
2Acety
lCoA
Glycolysis
Glucose
2Pyruva
te
2 NADH
2 NADH
6 NADH
2 FADH2
2 FADH2
2 NADH
CYTOSOL Electron shuttlesspan membrane o
r
MITOCHONDRION
Process NADH FADH2 ATPGlycolysis 2 0 2
Krebs Cycle 8 2 2Oxidative
PhosphorylationTotal x 3 =10 x 3 = 30
Total X 2 =2 x 2 = 4
34*
Maximum per glucose = 36 to 38*depends on which shuttle transports electrons from NADH in
cytosol – may cost 2 ATP in that case OP = 32
ATP yield per Glucose at each Stage