bio ch 7

inside an active mitochondrion, most electrons follow which pathway?

citric acid cycle --> NADH --> electron transport chain --> oxygen

where does glycolysis take place in eukaryotic cells?

cytosol

a young dog has never had much energy. he is brought to a vet for help and she decides to conduct tests. she discovers that the dog's mitochondria can use only fatty acids and amino acids for respiration and his cells produce more lactate than normal. of the following, which is the best explanation of the dog's condition?

his mitochondria lack the transport protein that moves pyruvate across the outer mitochondrial membrane

even though plants carry on photosynthesis, plant cells still use their mitochondria for oxidation of pyruvate. when and where will this occur?

in all cells all the time

why does the oxidation of organic compounds by molecular oxygen to produce CO2 and water release free energy?

electrons are being moved from atoms that have a lower affinity for electrons (such as C) to atoms with a higher affinity for electrons (such as O)

in chemiosmosis, what is the most direct source of energy that is used to convert ADP + i to ATP

energy released from movement of protons through ATP synthase, down their electrochemical gradient

during aerobic respiration, electrons travel downhill in which sequence?

food --> NADH --> electron transport chain --> oxygen

what carbon sources can yeast cells metabolize to make ATP from ADP under anaerobic conditions?

glucose

yeast cells that have defective mitochondria incapable of respiration will be able to grow by catabolizing which of the following carbon sources for energy?

glucose

which metabolic pathway is common to both cellular respiration and fermentation?

glycolysis

which metabolic pathway is common to both fermentation and cellular respiration of a glucose molecule?

glycolysis

which of the following normally occurs regardless of whether or not oxygen (O2) is present?

glycolysis

which process in eukaryotic cells will proceed normally whether oxygen (O2) is present or absent?

glycolysis

which of the following occurs in the cytosol of a eukaryotic cell?

glycolysis and fermentation

which statement best supports the hypothesis that glycolysis is an ancient metabolic pathway that originated before the last universal common ancestor of life on earth

glycolysis is widespread and is found in the domains bacteria, archaea, and eukarya.

in prokaryotes, the respiratory electron transport chain is located

in the plasma membrane

where is the ATP synthase located in the mitochondrion?

inner membrane

an organism is discovered that thrives both in the presence and absence of oxygen in the air. curiously the consumption of sugar increases as oxygen is removed from the organism's environment, even though the organism does not gain much weight. this organism

is a facultative anaerobe

which catabolic processes mazy have been used by cells on ancient earth before free oxygen became available

glycolysis, pyruvate oxidation, the citric acid cycle, and oxidative phosphorylation, using an electron acceptor other than oxygen

a molecule that is phosphorylated

has an increased chemical potential energy; it is primed to do cellular work

if a cell is able to synthesize 30 ATP molecules for each molecule of glucose completely oxidized to carbon dioxide and water, approximately how many ATP molecules can the cell synthesize for each molecule of pyruvate oxidized to carbon dioxide and water?

14

how many carbon atoms are fed into the citric acid cycle as a result of the oxidation of one molecule of pyruvate?

2

starting with one molecule of glucose, the energy containing products of glycolysis are

2 NADH 2 pyruvate 2 ATP

in glycolysis, for each molecule of glucose oxidized to pyruvate

2 molecules of ATP are used and 4 molecules of ATP are produced

what fraction of the carbon dioxide exhaled by animals is generated by the reactions of the citric acid cycle if glucose is the sole energy source?

2/3

chemiosmotic ATP synthesis (oxidative phosphorylation) occurs in

all respiring cells, both prokaryotic and eukaryotic, using either oxygen or other electron acceptors.

which kind of metabolic poison would most directly interfere with glycolysis?

an agent that closely mimics the structure of glucose but is not metabolized

the synthesis of ATP by oxidative phosphorylation, using the energy released by movement of protons across the membrane down their electrochemical gradient, is an example of

an endergonic reaction coupled to an xergonic reaction

why is glycolysis considered to be one of the first metabolic pathways to have evolved?

it does not involve organelles or specialized structures, does not require oxygen, and is present in most organisms

in liver cells, the inner mitochondrial membranes are about 5 times the area of the outer mitochondrial membranes. what purpose must this serve?

it increases the surface for oxidative phosphorylation

when an individual is exercising heavily and when the muscle becomes oxygen deprived, muscle cells convert pyruvate to lactate. what happens to the lactate in skeletal muscle cells?

it is taken to the liver and converted back to pyruvate

why is glycolysis described as having an investment phase and a payoff phase

it uses stored ATP and then forms a net increase in ATP

you have a friend who lost 7 kg (about 15 pounds) of fat on a regimen of strict diet and exercise. how did the fat leave her body?

it was released as CO2 and H2O

during aerobic respiration, H2O is formed. where does the oxygen atom for the formation of the water come from?

molecular oxygen (O2)

carbon dioxide (CO2) is released during which of the following stages of cellular respiration?

oxidation of pyruvate to acetyl CoA and the citric acid cycle

which of the following produces the most ATP when glucose is completely oxidized to carbon dioxide and water?

oxidative phophorylation (chemiosmosis)

one function of both alcohol fermentation and lactic acid fermentation is to

oxidize NADH to NAD+

when a glucose molecule loses a hydrogen atom as a result of an oxidation-reduction reaction, the molecule becomes

oxidized

the final electron acceptor of the electron transport chain that functions in aerobic oxidative phophorylation is

oxygen

in mitochondria, exergonic redox reactions

provide the nervy that establishes the proton gradient

what is the oxidizing agent in the following reaction? pyruvate + NADH + (H+) --> lactate + (NAD+)

pyruvate

when a molecule of NAD+ (nicotinamide adenine dinucleotide) gains a hydrogen atom (not a proton), the molecule becomes

reduced

in alcohol fermentation, NAD+ is regenerated from NADH by

reduction of acetaldehyde to ethanol (ethyl alcohol)

during glycolysis, when each molecule of glucose is catabolized to two molecules of pyruvate, most of the potential energy contained in glucose is

retained in 2 pyruvates

an electron loses potential energy when it

shifts to a more electronegative atom

the ATP made during fermentation is generated by which of the following?

substrate level phosphorylation

the ATP made during glycolysis is generated by

substrate-level phosphorylation

most CO2 from catabolism is released during

the citric acid cycle

when hydrogen ions are pumped from the mitochondrial matrix across the inner membrane and into the inter membrane space, the result is

the creation of a proton motive force

what is proton motive force?

the force provided by a transmembrane hydrogen ion gradient

the immediate energy source that drives ATP synthesis by ATP synthase during oxidative phosphorylation is the

H+ movement down its concentration gradient

where do the catabolic products of fatty acid breakdown enter into the citric acid cycle?

acetyl CoA

substrate level phosphorylation accounts for approximately what percentage of the ATP formed by the reactions of glycolysis?

100%

how many oxygen molecules (O2) are required each time a molecule of glucose (C6H12O6) is completely oxidized to carbon dioxide and water via aerobic respiration?

6

approximately how many molecules of ATP are produced from the complete oxidation of two molecules of glucose in aerobic cellular respiration?

60-64

in the absence of oxygen, yeast cells can obtain energy by fermentation, resulting in the production of

ATP CO2 and ethanol (ethyl alcohol)

in a mitochondrion, if the matrix ATP concentration is high and the inter membrane space proton concentration is too low to generate sufficient proton motive force then

ATP synthase will hydrolyze ATP and pump protons into the inter membrane space

brown fat cells produce a protein called thermogenin in their mitochondrial inner membrane. thermogenin is a channel for facilitated transport of protons across the membrane. what will occur in the brown fat cells when they produce thermogenin?

ATP synthesis will decrease and heat generation will increase

which of the following statements describes the results of this reaction? C6H12O6 + 6O2 --> 6CO2 + 6 H2O + energy

C6H12O6 is oxidized and O2 is reduced

during aerobic respiration, which of the following directly donates electrons to the electron transport chain at the lowest energy level?

FADH2

which of the following statements describes NAD+

NAD+ is reduced to NADH during glycolysis, pyruvate oxidation, and the citric acid cycle

in addition to ATP what are the end products of glycolysis

NADH and pyruvate

in cellular respiration, the energy for most ATP synthesis is supplied by

a proton gradient across a membrane

the oxygen consumed during cellular respiration is involved directly in which process or event?

accepting electrons at the end of the electron transport chain

the primary role of oxygen in cellular respiration is to

act as an acceptor for electrons and hydrogen, forming water

what is the purpose of beta oxidation in respiration?

breakdown of fatty acids

during intense exercise, as skeletal muscle cells switch to fermentation, the human body will increase its catabolism of

carbohydrates only

what is the term for metabolic pathways that release stored energy by breaking down complex molecules?

catabolic pathways

the molecule that functions as the reducing agent (electron donor) in a redox or oxidation-reduction reaction

loses electrons and potential energy

where are the proteins of the electron transport chain located

mitochondrial inner membrane

energy released by the electron transport chain is used to pump H+ into which location in eukaryotic cells?

mitochondrial intermembrane space

the free energy for the oxidation of glucose to CO2 and water is -686 kcal/mol and the free energy for the reduction of NAD+ to NADH is +53 kcal/mol. why are only two molecules of NADH formed during glycolysis when it appears that as many as a dozen could be formed?

most of the free energy available from the oxidation of glucose remains in pyruvate, one of the products of glycolysis

when electrons move closer to a more electronegative atom, what happens?

the more electronegative atom is reduced and energy is released

a mutation in yeast makes it unable to convert pyruvate to ethanol. how will this mutation affect these yeast cells?

the mutant yeast will be unable to grow anaerobically

when electrons flow along the electron transport chains of mitochondria, which of the following changes occurs?

the pH of the matrix increases

the direct energy source that drives ATP synthesis during respiratory oxidative phophorylation in eukaryotic cells is

the proton motive force across the inter mitochondrial membrane

why are carbohydrates and fats considered high energy foods

they have a lot of electrons associated with hydrogen

in vertebrate animals, brown fat tissue's color is due to abundant blood vessels and capillaries. white fat tissue, on the other hand is specialized for fat storage and contains relatively few blood vessels or capillaries. brown fat cells have a specialized protein that dissipates the proton motive force across the mitochondrial membranes. which of the following might be the function of the brown fat tissue?

to regulate temperature by converting most of the energy from NADH oxidative to heat