7.1 An Overview of Cellular Respiration Flashcards Preview

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Flashcards in 7.1 An Overview of Cellular Respiration Deck (61)
1

catabolism

describes the set of chemical reactions that break down molecules into smaller units, releases chemical energy that can be stored in molecules of ATP

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anabolism

the set of chemical reactions that build molecules from smaller units, require an input of energy, usually in the form of ATP

3

cellular respiration is one of the major sets of:

catabolic reactions in a cell

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cellular respiration is a series of catabolic reactions that converts the energy stored in food molecules into:

the energy stored in ATP

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what are the wastes or by-products of cellular respiration?

carbon dioxide and water

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aerobic respiration

cellular respiration that occurs in the presence of oxygen

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anaerobic respiration

cellular respiration that occurs in the absence of oxygen

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oxygen is consumed in aerobic respiration; the products are:

carbon dioxide and water

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carbohydrates and lipids have a large amount of potential energy in their chemical bonds, whereas:

carbon dioxide and water have less potential energy in their bonds

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cellular respiration releases a large amount of energy because:

the sum of the potential energy in all of the chemical bonds of the reactants is higher than that of the products

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the maximum amount of free energy released during cellular respiration is:

-686kcal per mole of glucose

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if all the energy stored in glucose were released at once:

most of it would be released as heat and the cell would not be able to harness it to do work

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in cellular respiration, energy is released:

gradually in a series of chemical reactions; this allows some of the energy to be used to form ATP

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how many molecules of ATP are produced from the aerobic respiration of a single molecule of glucose?

32

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in most organisms, cellular respiration consumes oxygen and produces ATP by...?

substrate-level phosphorylation and oxidative phosphorylation, as well as carbon dioxide and water

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how much of the total energy released by aerobic respiration is harnessed in the form of ATP?

34% with the remainder of the energy given off as heat

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what are the two different ways to produce ATP from the chemical energy stored in a molecule of glucose?

substrate-level phosphorylation and oxidative phosphorylation

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substrate-level phosphorylation

a way of generating ATP in which a phosphate group is transferred to ADP from an organic molecule, which acts as a phosphate donor or substrate

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in the case of substrate-level phosphorylation, there are two coupled reactions carried out by a single enzyme:

the hydrolysis of a phosphorylated organic molecule and the addition of a phosphate group to ADP

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substrate-level phosphorylation produces only:

a small amount of the total ATP generated in cellular respiration (12%)

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electron carrier

a molecule that carries electrons (and energy) from one set of reactions to another

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electron transport chain

the system that transfers electrons along a series of membrane-associated proteins to a final electron acceptor, using the energy released as electrons move down the chain to produce ATP

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in aerobic respiration, oxygen is the:

final electron acceptor, resulting in the formation of water

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oxidative phosphorylation

a set of metabolic reactions that occurs by passing electrons along an electron transport chain to the final electron acceptor, oxygen, pumping protons across a membrane, and using the proton electrochemical gradient to drive synthesis of ATP

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electron transport chains are used in respiration to:

harness energy from fuel molecules

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outline the major steps in oxidative phosphorylation:

chemical energy of organic molecules are broken down by catabolism, electrons carriers transport electrons and energies to the electron transport chain, electron transport chains transfer electrons along a series of membrane-associated proteins to a final electron acceptor and in the process harness the energy released to produce ATP, oxygen is final electron acceptor and forms water as a product

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oxidation-reduction reactions

a reaction involving the loss and gain of electrons between reactants. In biological systems these reactions are often used to store or release chemical energy

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oxidation

the loss of electrons

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reduction

the gain of electrons

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the loss and gain of electrons always occur together in a :

coupled oxidation-reduction reaction

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what occurs in a coupled oxidation-reduction reaction?

electrons are transferred from one molecule to another so that one molecule loses electrons and one molecule gains those electrons

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the oxidized molecule....

loses electrons

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the reduced molecule....

gains electrons

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what are two important electron carriers in cellular respiration?

nicotinamide adenine dinucleotide (NAD+) and flavin adenine dinucleotide (FAD)

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what is the reduced form of NAD+ and FAD?

NADH and FADH2

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in redox reactions involving organic molecules (ex. NAD+ and FAD), the gain or loss of electrons if often accompanied by:

the gain or loss of protons (H+)

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reduced molecules can easily be recognized by:

an increase in C-H bonds and the corresponding oxidized molecules by a decrease in C-H bonds

38

in their reduced forms, NADH and FADH2 can :

donate electrons, this allows electrons (and energy) to be transferred to the electron transport chain

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the oxidation of NADH and FADH2 also produces:

NAD+ and FAD which can then accept electrons from the breakdown of fuel molecules

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electron carriers act as shuttles, transferring electrons derived from:

the oxidation of fuel molecules (Ex. glucose) to the electron transport chain

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even though it consists of many steps, cellular respiration can be understood as a:

redox reaction (glucose is oxidized producing carbon dioxide, oxygen is reduced forming water)

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in carbon dioxide, how are electrons shared?

not equally, the oxygen atom is more electronegative than the carbon atom, as a result, carbon has partially lost electrons to oxygen and is oxidized

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in glucose, carbon atoms share electrons...

equally

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in oxygen gas, electrons are shared...

equally between two oxygen atoms

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in water, the electrons that are shared between hydrogen and oxygen are more likely to be found near:

oxygen because the oxygen is more electronegative. as a result, oxygen has partially gained electrons and is reduced

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glucose is a good electron donor because:

its oxidation to carbon dioxide releases a lot of energy

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oxygen is a good electron acceptor because:

it has a high affinity for electrons

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in cellular respiration, glucose is not:

oxidized all at once to carbon dioxide, oxidized in a series of reactions to release energy in a controlled manner

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some of the energy released in the series of reactions between glucose being oxidized to produce carbon dioxide can be:

used to synthesize ATP directly and some of it is stored temporarily in reduced electron carriers and then used to generate ATP by oxidative phosphorylation

50

cellular respiration has how many stages?

4

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glycolysis

the breakdown of glucose to pyruvate; the first stage of cellular respiration

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outline the process of stages 1 (glycolysis):

glucose is partially broken down to make pyruvate and energy is transferred to ATP and reduced electron carriers

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what occurs in stage 2 of cellular respiration?

pyruvate is oxidized to another molecule called acetyl-coenzyme A (acetyl-CoA), producing reduced electron carriers and releasing carbon dioxide

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citric acid cycle (tricarboxylic -TCA cycle or the Krebs cycle)

the third stage of cellular respiration, in which acetyl-CoA is broken down and more carbon dioxide is released

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outline the citric acid cycle:

acetyl-CoA enters stage 3, completely oxidized to carbon dioxide and energy is transferred to ATP and reduced electron carriers. The amount of energy transferred to ATP and reduced electron carriers in this stage is nearly twice that of stages 1 and 2 combined

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oxidative phosphorylation

a set of metabolic reactions that occurs by passing electrons along an electron transport chain to the final electron acceptor, oxygen, pumping protons across a membrane, and using the proton electrochemical gradient to drive synthesis of ATP

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outline what occurs in stage 4 of cellular respiration:

reduced electron carriers generated in stages 1-3 donate electrons to the electron transport chain and a large amount of ATP is produced

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outline where the stages of cellular respiration occur in eukaryotes:

glycolysis takes place in the cytoplasm, pyruvate oxidation/citric acid cycle/oxidative phosphorylation all take place in mitochondria

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the electron transport chain is made up of:

proteins and small molecules associated with the inner mitochondrial membrane

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where do reactions of cellular respiration occur in bacteria?

it takes place in the cytoplasm and the electron transport chain is located in the plasma membrane

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the change in the free energy is much greater for the steps that generate:

reduced electron carriers composed to those that produce ATP directly