Chapter 9 Flashcards
Fermentation
-Catabolic process
Is a partial degradation of sugars or other organic fuel that occurs without the use of oxygen.
The relocation of electrons releases energy stored in organic molecules, and this energy ultimately is used to synthesize ATP.
True
Oxidation-reduction reactions (redox reactions)
Electron transfers during chemical reactions.
Oxidation
The loss of electrons from one substance.
Reduction
The addition of electrons to another substance.
Reducing agent
The electron donor.
Oxidizing agent
The electron acceptor.
An electron loses potential energy when it shifts from a less electronegative atom toward a more electronegative one.
True
Only the barrier of activation energy holds back the flood of electrons to a lower energy state.
True
NAD+
Electron carrier, coenzyme
Nicotinamide adenine dinucleotide (a derivative of the vitamin niacin)
Reduced state of NAD+
NADH
Electron transfer from NADH to oxygen is an exergonic reaction.
True
Terminal electron acceptor
Has the greatest affinity for electrons in the ETC.
In summary, during cellular respiration, most electrons travel the following “downhill” route:
Glucose —> NADH —> ETC —> Oxygen
Glycolysis occurs in…
The cytosol
Oxidative phosphorylation
The production of ATP using energy derived from the redox reactions of an electron transport chain.
-Is constituted by electron transport and chemiosmosis
In eukaryotic cells, ____________________ is the site of electron transport and chemiosmosis
the inner membrane of the mitochondrion
In prokaryotes, in the plasma membrane
Substrate-level phosphorylation
The enzyme-catalyzed formation of ATP by direct transfer of a phosphate group to ADP from an intermediate substrate in catabolism.
For each molecule of glucose degraded to carbon dioxide and water by respiration, the cell makes up to about ____ molecules of ATP, each with ___________ of free energy.
32, 7.3kcal/mol
The two phases of glycolysis
The energy investment phase
The energy payoff phase
FAD
Flavin adenine dinucleotide
-derived from riboflavin
FAD accepts _________________ to become FADH2
2 electrons and 2 protons
The total yield per glucose from the citric acid cycle turns out to be…
6 NADH, 2 FADH2, and the equivalent of 2 ATP
Ubiquinone (Coenzyme Q)
The only member of the electron transport chain that is not a protein.
-Electron carrier
The power source for ATP synthase is a difference in the concentration of H+ on opposite sides of the inner mitochondrial membrane.
True
Chemiosmosis
The process in which energy stored in the form of hydrogen ion gradient across a membrane is used to drive cellular work such as the synthesis of ATP
Proton-motive force
The potential energy stored in the form of a proton electrochemical gradient, generated by the pumping of H+ across a biological membrane during chemiosmosis.
During respiration, most energy flows in this sequence:
Glucose —> NADH —> ETC —> Proton-motive force —> ATP
Glycolysis produces per molecule of glucose :
2 NADH
2 Pyruvate
2 ATP by substrate-level phosphorylation
Pyruvate oxidation produces per molecule of glucose :
2 Acetyl CoA
2 NADH
Citric Acid Cycle produces per molecule of glucose:
6 NADH
2 FADH2
2 ATP by substrate-level phosphorylation
Oxidative Phosphorylation produces per molecule of glucose:
26 or 28 ATP by oxidative phosphorylation
Each NADH that transfers a pair of electrons from glucose to the ETC contributes enough to the proton-motive force to generate a maximum of about _________
3 ATP
About 34% of the potential chemical energy in glucose is transferred to ATP.
True
Difference between anaerobic respiration and fermentation.
An electron transport chain is used in anaerobic respiration but not in fermentation.
Fermentation consists of glycolysis plus reactions that regenerate NAD+ by transferring electrons from NADH to pyruvate or derivatives of pyruvate.
True
In alcohol fermentation,
Pyruvate is converted to ethanol in two steps.
Pyruvate —> acetaldehyde —> ethanol
Loses CO2. Reduced
During lactic acid fermentation,
Pyruvate is reduced directly by NADH to form lactate as an end product, with no release of CO2.
Obligate anaerobes
Carry out only fermentation or anaerobic respiration.
Facultative anaerobes
Can make ATP to survive using either fermentation or respiration.
(Our muscle cells)
Protein’s possible pathways in ATP harvesting
Pyruvate
Acetyl CoA
Citric Acid Cycle
Fats possible pathways in harvesting ATP
Glycerol —> Glyceraldehyde-3-Phosphate
Fatty acids —> Acetyl CoA
Beta oxidation
A metabolic sequence that breaks fatty acids down to two-carbon fragments, which enter the citric acid cycle as acetal CoA.
- NADH and FADH2 are also generated.
A gram of fat oxidized by respiration produces more than twice as much ATP as a gram of carbohydrate.
True
Phosphofructokinase can be considered the pacemaker of respiration.
True
