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Chapter 9

Cellular Respiration
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Be familiar with the chemical equation for the degradation of glucose.
C6H12O6 + 6O2 ------> 6CO2 + 6H2O.
Define oxidation and reduction and what a redox reduction is.
Oxidation: The loss of electrons from one substance.

Reduction: The addition of electrons to another substance.

Redox reaction: Involve the partial or complete transfer of one or more electrons from one reactant to another.
Define the role of NAD+ in cellular respiration.
A location where dehydrogenase enzymes transfer electrons

NAD acts as an electron and hydrogen carriers in some oxidation-reduction reactions.
In general terms, explain the role of the electron transport chain in cellular respiration.
NADPH passes electrons to the electron transport chain, from which they eventually combine with hydrogen ions and oxygen to form water.
Anaerobic respiration
The use of inorganic molecules other than oxygen to accept electrons at the "downhill" end of electron transport chains.
Electron transport chain
A group of carrier molecules located in the inner mitochondrial membrane (or plasma membrane of aerobic prokaryotes).
Glycolysis
Occurring in the cytosol, breaks glucose into two molecules of pyruvate.
Fermentation
Occurs without oxygen, is the partial degradation of sugars to release energy; A catabolic process that makes a limited amount of ATP from glucose without an electron transport chain and that produces a characteristic end product, such as ethyl alcohol or lactic acid.
Aerobic respiration
Uses oxygen in the breakdown of glucose (or other energy-rich organic compounds) to yield carbon dioxide and water and release energy as ATP and heat.
Oxidation
The loss of electrons from one substance.
NAD+/NADH
NAD+ (nicotinamide adenine dinucleotide)
Citric acid cycle
Located in the mitochondrial matrix or in the cytoplasm of prokaryotes, oxidizes a derivative of pyruvate into carbon dioxide.
Oxidative phosphorylation
A process that includes electron transport and chemiosmosis.
Name the three stages of cellular respiration and state the region of the eukaryotic cell where each stage occurs.
Glycolysis, citric acid cycle, oxidative phosphorylation

Glycolysis is located in the cytosol, citric acid cycle and oxidative phosphorylation is located in the mitochondrial matrix.
Explain why ATP is required for the preparatory steps of glycolysis.
Two molecules of ATP are consumed as glucose is split into two three-carbon sugars (glyceraldehyde 3-phosphate).The conversion of these molecules to pyruvate produces two NADH and four ATP by substrate-level phosphorylation.
Substrate-level phosphorylation
An enzyme transfers a phosphate group from a substrate molecule to ADP.
Understand how substrate-level phosphorylation is used in glycolysis.
The conversion of these molecules to pyruvate produces two NADH and four ATP by substrate-level phosphorylation.
List the products of the citric acid cycle.
2 CO2, 3 NADH, acetyl CoA, 1 FADH2, 1 ATP
Distinguish between substrate-level phosphorylation and oxidative phosphorylation.
Substrate-level phosphorylation: An enzyme transfers a phosphate group from a substrate molecule to ADP; no electron transport chain

Oxidative phosphorylation:A process that includes electron transport and chemiosmosis, with electron transport chain.
In general terms, explain how the exergonic "slide" of electrons down the electron transport chain is coupled to the endergonic production of ATP by chemiosmosis.
In mitochondria, exergonic redox reactions produce the H+ gradient that drives the production of ATP.
ATP synthase
A protein complex embedded in the inner membrane, uses the energy of a protein (H+) gradient to make ATP.
Chemiosmosis
The movement of ions across a selectively-permeable membrane, down their electrochemical gradient.
Protein-motive force
The result of proton gradient stores potential energy.
Explain where and how the respiratory electron transport chain creates a proton gradient. Explain why this gradient is described as a proton force.
The electron transport chain creates the proton gradient. When some members of the chain pass electrons, they also accept and release protons, which are pumped into the intermembrane space at three points. The resulting proton gradient stores potential energy, referred to as the proton-motive force.
Distinguish between fermentation and anaerobic respiration.
Fermentation: Occurs without oxygen, is the partial degradation of sugars to release energy; A catabolic process that makes a limited amount of ATP from glucose without an electron transport chain and that produces a characteristic end product, such as ethyl alcohol or lactic acid.

Anaerobic respiration: The use of inorganic molecules other than oxygen to accept electrons at the "downhill" end of electron transport chains.
State the basic function of fermentation.
A catabolic process that makes a limited amount of ATP from glucose without an electron transport chain and that produces a characteristic end product, such as ethyl alcohol or lactic acid.
Compare the processes of fermentation.
Alcoholic Fermentation: Pyruvate is converted into acetaldehyde, and CO2 is released. Acetaldehyde is then reduced by NADH to form ethanol (ethyl alcohol), and NAD+ is regenerated.

Lactic Fermentation: Pyruvate is reduced directly by NADH to form lactate and recycle NAD+. Muscle cells make ATP by lactic acid fermentation when energy demand is high and oxygen supply is low.
How are food molecules other than glucose metabolized?
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Beta oxidation
Breaks down intermediate of glycolysis and fatty acids to two-carbon fragments that enter the citric acid cycle as acetyl CoA.

A metabolic sequence that breaks fatty acids down to two-carbon fragments that enter the citric acid cycle as acetyl CoA.
Anabolic pathway
A metabolic pathway that consumes energy to synthesize a complex molecule from simpler compounds.
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