cellular respiration

Following glycolysis and the citric acid cycle, but before the electron transport chain and oxidative phosphorylation, the carbon skeleton of glucose has been broken down to CO2 with some net gain of ATP. Most of the energy from the original glucose molecule at that point in the process, however, is in the form of...

NADH

Exposing inner mitochondrial membranes to ultrasonic vibrations will disrupt the membranes. However, the fragments will reseal "inside out." The little vesicles that result can still transfer electrons from NADH to oxygen and synthesize ATP. After the disruption, when electron transfer and ATP synthesis still occur, what must be present?

all of the electron transport proteins and ATP synthase

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

glycolysis

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

100%

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

Starting with one molecule of glucose, the energy-containing products of glycolysis are...

2 NADH, 2 pyruvate, and 2 ATP

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

2/3

Starting with citrate, which of the following combinations of products would result from three acetyl CoA molecules entering the citric acid cycle (see the accompanying figure)?

3 ATP, 6 CO2, 9 NADH, and 3 FADH2

Approximately how many molecules of ATP are produced from the complete oxidation of one molecule of glucose (C6H12O6) in aerobic cellular respiration?

30-32

For each mole of glucose (C6H12O6) oxidized by cellular respiration, how many moles of CO2 are released in the citric acid cycle (see the accompanying figure)?

4

Which of the listed statements describes the results of the following reaction?

C6H12O6 is oxidized and O2 is reduced.

New biosensors, applied like a temporary tattoo to the skin, can alert serious athletes that they are about to "hit the wall" and find it difficult to continue exercising. These biosensors monitor lactate, a form of lactic acid, released in sweat during strenuous exercise. Which of the statements below is the best explanation of why athletes would need to monitor lactate levels?

During anaerobic respiration, lactate levels increase when muscles cells need more energy; however, muscles cells eventually fatigue, thus athletes should modify their activities to increase aerobic respiration.

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

FADH2

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 five times the area of the outer mitochondrial membranes. What purpose must this serve?

It increases the surface for oxidative phosphorylation.

Which of the following statements about NAD+ is true?

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

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

accepting electrons at the end of the electron transport chain

In the presence of oxygen, the three-carbon compound pyruvate can be catabolized in the citric acid cycle. First, however, the pyruvate (1) loses a carbon, which is given off as a molecule of CO2, (2) is oxidized to form a two-carbon compound called acetate, and (3) is bonded to coenzyme A. Which one of the following is formed by the removal of a carbon (as CO2) from a molecule of pyruvate?

acetyl CoA

Even though plants cells photosynthesize, they still use their mitochondria for oxidation of pyruvate. This will occur in...

all cell or the other cell one

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

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

Canine phosphofructokinase (PFK) deficiency afflicts Springer spaniels, affecting an estimated 10% of the breed. Given its critical role in glycolysis, one implication of the genetic defect resulting in PFK deficiency in dogs is...

an intolerance for exercise

During aerobic respiration, electrons travel downhill in which sequence?

glucose → NADH → electron transport chain → oxygen

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

glycolysis and fermentation

The chemiosmotic hypothesis is an important concept in our understanding of cellular metabolism in general because it explains...

how ATP is synthesized by a proton motive force

Substrate-level phosphorylation occurs...

in both glycolysis and the citric acid cycle

The electron transport chain...

is a series of redox reactions

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

loses electrons and loses 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

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

molecular oxygen (O2)

Fatty acids usually have an even number of carbons in their structures. They are catabolized by a process called beta-oxidation. The end products of the metabolic pathway are acetyl groups of acetyl CoA molecules. These acetyl groups...

not are directly decarboxylated by pyruvate dehydrogenase, not transport chain

One function of both alcohol fermentation and lactic acid fermentation is to...

oxidize NADH to NAD+

When electrons move closer to a more electronegative atom, what happens? The more electronegative atom is...

reduced, and energy is released

Most of the CO2 from the catabolism of glucose is released during...

the citric acid cycle

In glycolysis, for each molecule of glucose oxidized to pyruvate...

two molecules of ATP are used and four molecules of ATP are produced.