1. _____________________ and ________________ are catabolic, energy-yielding pathways Complex...
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![Page 1: 1. _____________________ and ________________ are catabolic, energy-yielding pathways Complex molecule (High energy) Simpler molecule (Low energy) Enzyme.](https://reader035.fdocuments.us/reader035/viewer/2022062516/56649d375503460f94a0f5d9/html5/thumbnails/1.jpg)
1. _____________________ and ________________ are catabolic, energy-yielding pathways
Complex molecule(High energy)
Simpler molecule(Low energy)
Enzyme+ heat + energy
Catabolic processes
1. ________________- to be discussed later
2 common types
2. ____________________-
•Organic compounds + O2 CO2 + H2O + Energy
Note: • This process uses _________.• This occurs in the _______________
CHAPTER 9CELLULAR RESPIRATION
•Organic compounds CO2 + H2O + Energy
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• An example of cellular respiration- _____________ of glucose
C6H12O6 + 6O2 6CO2 + 6H2O + Energy (ATP + heat)Glucose
• An ________________reaction G = - 686 kcal per mole of glucose.
• Drives the generation of ATP from ADP
ATP then ____________________ other molecules, allowing them to do work
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• _______ (reduction-oxidation) reactions- transfer of electrons from one reactant to another or changes bond type (single to double).
• The loss of electrons is called _____________.
• The addition of electrons is called _____________.
2. _______ reactions release ___________ when electrons move closer to _____________ atoms
• Example:
• NaCl Na+ + Cl-
• sodium is ____________and chlorine is ____________
• Na is the ____________________ and reduces Cl.
• Cl is the _____________________ and oxidizes Na.
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• In the summary equation of cellular respiration: C6H12O6 + 6O2 6CO2 + 6H2O
• Glucose is ___________, oxygen is ____________, and electrons loose potential energy.
3. Electrons “fall” from organic molecules to ________ during cellular respiration
•At key steps, hydrogen atoms are stripped from glucose and passed first to a coenzyme, like NAD+ (nicotinamide adenine dinucleotide).
• Dehydrogenase enzymes strip two hydrogen atoms from the fuel (e.g., glucose), pass _______________ ________to NAD+ (to make NADH) and release H+.
• H-C-OH + NAD+ -> C=O + NADH + H+
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Fig. 9.4
•NAD + functions as the __________________ in many of the redox steps during the catabolism of glucose.
•Energy is tapped to synthesize ATP as electrons “fall” from __________ to oxygen.
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Fig. 9.5
• The________ ___________
_______ breaks the fall of electrons to __ into several steps.
• ________ shuttles electrons to the “top” of the chain.
• At the “bottom”, oxygen captures the ___________ and ___ to form water.
• The free energy change from “top” to “bottom” is ___ kcal/mole of NADH.
Energy used to make ATP!
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1. Respiration involves glycolysis, the Krebs cycle, and electron transport
Fig. 9.6
1. __________(In cytoplasm)
2. ______________(in mitochondrial matrix)
3. ___________ ____________ (In inner mitochondrial membrane)
End result: ATP is generated
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Glucose 2 Pyruvate 6 CO2
2 ADP 2 ATP 2 ADP 2 ATP
8 NADH2 NAD+ _________ 8 NAD+
2 FAD+ 2 FADH2
_____6 ADP 28 ADP _________
__________ ______
____________________
Add up total ATP generated : 2+2+6+28=___
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• In the electron transport chain-
• the _________ move from molecule to molecule until they combine with oxygen and hydrogen ions to form __________.
• As they are passed along the chain, the energy carried by these electrons is stored in the mitochondrion in a form that can be used to synthesize ATP via _____________________________________.
• Oxidative phosphorylation produces almost ____ of the ATP generated by respiration.
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Glucose 2 Pyruvate 6 CO2
2 ADP 2 ATP 2 ADP 2 ATP
These are generated by ______________________________
Enzyme•An _______ transfers a phosphate group from an organic molecule (the substrate) to ____, forming ____.
What is substrate level phosphorylation?
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• Glucose, a six-carbon sugar, is split into two, 3-carbon sugars then into ________.
• Each of ___ steps in glycolysis is catalyzed by a specific _________.
2. Glycolysis
Divided into two phases: 1. an _______________
__________• 2 ATP used
2. an _____________ _________.• 4 ATP + 2 NADH
produced
Net = 2 ATP + 2 NADH
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Fig. 9.9a
1st Phosphate groupadded
2nd Phosphate groupadded
Two 3-carbon molecules, each with one phosphate
Glycolysis Energy investment phase
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Fig. 9.9b
2 PO4
1 PO4
0 PO4
Energy payoff phase
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• If ___________ is present, pyruvate enters the _________________ where enzymes of the Krebs cycle complete the ______________ of the organic fuel to carbon dioxide.
3. The Krebs cycle completes the energy-yielding __________ of organic molecules
Glucose 2 Pyruvate 6 CO2
2 ADP 2 ATP 2 ADP 2 ATP
KrebsGlycolysis
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What happens to pyruvate?
• Answer- Pyruvate is modified to ____________ which enters the Krebs cycle in the matrix.
• 1. A _______________ group is removed as CO2.
• 2. A pair of ______________ is transferred from the remaining two-carbon fragment to NAD+ to form NADH.
• 3. The oxidized fragment, acetate, combines with coenzyme A to form ___________
Fig. 9.10
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• The Krebs cycle consists of ____ steps.
Fig. 9.12
• Each cycle produces
• one ATP by _____________ _____________• three ________• and one ______
Named after Hans Kreb – 1930s
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• The conversion of pyruvate and the Krebs cycle produces large quantities of _______________.
Fig. 9.11
2 carbon atoms enter
2 carbon atoms released as CO2
Note the Krebs cycle is never depleted of ________: 2 in, 2 out
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• Only __ of __ ATP produced by respiration of glucose are derived from ________________ ________________________.
• The vast majority of the ATP comes from the energy in the ________ carried by ______ (and ________).
4. The inner mitochondrial membrane couples _____________ to ATP synthesis
• Thousands of copies of the electron transport chain are found in the _________ (the inner membrane of the mitochondrion).
• Electrons drop in _____________ as they pass down the electron transport chain.
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• Electrons carried by __________ are transferred to the first molecule in the electron transport chain, _____________________.
• The electrons continue along the chain which includes several ____________ proteins and one lipid carrier.
• The electrons carried by _____ have lower free energy and are added to a later point in the chain.
Fig. 9.13
•Electrons from NADH or FADH2 ultimately pass to oxygen.•The electron transport chain generates no ATP directly.
Note:
Electrons
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• A protein complex, ___ _______, in the cristae actually makes ATP from ADP and Pi.
• ATP uses the energy of a _____________ (from the electron transport chain) to power ATP synthesis.
• This __________________ develops between the intermembrane space and the ________.
• Termed _______________ ______________________
Fig. 9.14
Then where does the ATP come from??
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Fig. 9.15
• This coupling of the redox reactions of the electron transport chain to ______________ is called _____________________.
•In plants- light supplies the ____________•In bacteria, the H+ gradient is across the plasma membrane
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• Most energy is from __________________________
5. Cellular respiration generates many ___ molecules for each _____ molecule it _________: a review
glucose NADH ET chain proton-motive force ATP
• A one six-carbon glucose molecule is oxidized to six CO2 molecules.
• Some ATP is produced by substrate-level phosphorylation
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Fig. 9.16 Maximum yield is 38 ATP
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• How efficient is respiration in generating ATP?
• Complete oxidation of glucose = _______ kcal/mole.
• Formation of each ATP requires = _____ kcal/mole.
• Efficiency of respiration is
• ____ kcal/mole x ___ ATP/glucose = ___%. 686 kcal/mole glucose
• The other approximately 60% is lost as ______.
• Cellular respiration is remarkably efficient in energy conversion.
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• Oxidation refers to the loss of _______to any electron acceptor, not just to oxygen.
• In glycolysis, NAD+ is the ________ agent, not O2.
• Glycolysis generates _____ whether oxygen is present (aerobic) or not (anaerobic).
6. _____________ enables some cells to produce ATP without the use of _______
Fig. 9.17a
Problem- Fermentation (anaerobic catabolism) still requires NAD+ to accept electrons.
Solution-In _______________, NAD+ comes from the conversion of pyruvate to _________
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• A second solution to the NAD+ problem:
• __________________________
• ( pyruvate is reduced directly by NADH to form ___________)
• Muscle cells switch from _________respiration to lactic acid ___________ to generate ATP when __ is scarce.
• The waste product, lactate causes muscle fatigue but ultimately it is converted back to pyruvate in the liver.
Fig. 9.17b
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Compare respiration and fermentation
Respiration Fermentation
•Both use glycolysis to generate _______•Both use NAD+ as an _________________.
Similarities
Aerobic AnaerobicType
NAD+ regeneration
Organic molecules___
Energy yield
__ ATP___ ATP
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• At a cellular level, human _________ cells can behave as facultative anaerobes, but ________ cells cannot.
• For facultative _________, pyruvate is a fork in the metabolic road that leads to two alternative routes.
Fig. 9.18
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7. How do other ________________ fit into glycolysis and the Kreb cycle??
Answer- ____________ _____________ can all enter the pathway
•________ are degraded to amino acids, then deaminated (nitrogen secreted as urea, ammonia)
•______must be digested to glycerol and fatty acids.
•______________are broken down to glucose.
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• Intermediaries in glycolysis and the Krebs cycle can be diverted to _____________ pathways.
• Examples:
• a human cell can synthesize about ______ the 20 different amino acids by modifying compounds from the _____________.
• ___________ can be synthesized from pyruvate and fatty acids from acetyl CoA.
• Excess carbohydrates and proteins can be converted to _______ through intermediaries of glycolysis and the Krebs cycle.
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• Basic principles of ____________________ regulate the metabolic economy.
• If a cell has an excess of a certain amino acid, it typically uses feedback inhibition to prevent the diversion of more intermediary molecules from the Krebs cycle to the synthesis pathway of that amino acid.
• The rate of catabolism is also regulated, typically by the level of _________ in the cell.
• If ATP levels drop, catabolism speeds up to produce more ATP.
8. _____________________ control cellular respiration
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• Control of catabolism is based mainly on regulating the activity of __________ at strategic points in the catabolic pathway.
• One strategic point occurs in the third step of glycolysis, catalyzed by ______________________
Fig. 9.20
•When ATP levels are high, inhibition of this enzyme slows ________________.
•_____________, the first product of the Krebs cycle, is also an inhibitor of phosphofructokinase.