Ch.7

Once they have been processed through the citric acid cycle, the acetyl-CoA molecules from a single glucose molecule produce:

2 ATP, 6 NADH, 4 CO2.

True or False: Oxidation is the gain of electrons

False

True or false: By the time pyruvate is formed, most of the energy contained in glucose has been released

False

True or false: The majority of cells within the human body have a very high baseline amount of ATP, so cells are always prepared for any long-term activity.

False

Recall that fatty acids (like palmitic acid) can yield substantially more ATP when compared with glucose. Why doesn't aerobic respiration rely solely on fatty acids as energy sources, rather than glucose?

Fatty acids cannot be used by some vital tissues in the human body, such as the brain.

When a single pyruvate is converted to acetyl-CoA, the other products of the reaction are

NADH and CO2

True or false: Pyruvate oxidation is remarkably similar to glycolysis in that when one molecule of pyruvate enters into a mitochondrion, two molecules of acetyl-CoA are formed

false

Fermentation takes place:

in the cytoplasm.

Due to the pumping action of the electron transport chain, protons have a high concentration in the _____ and a low concentration in the _____.

intermembrane space; mitochondrial matrix

During the citric acid cycle, the production of CO2 is the result of the _____ of intermediate compounds of the citric acid cycle coupled to the production of _____.

oxidation; NADH

The electron transport chain is part of

oxidative phosphorylation.

In cellular respiration, glucose is _____ to CO2 and oxygen is _____ to water.

oxidized; reduced

In the absence of oxygen, fermentation:

regenerates NAD+ from the reduction of pyruvate.

Lactic acid and ethanol fermentation differ in that:

Ethanol fermentation produces CO2, but lactic acid fermentation does not.

ATP is not generated directly in the citric acid cycle; instead, an intermediate is first generated by substrate-level phosphorylation. The intermediate is:

GTP

You may be familiar with the story of Philippides, the famous Greek runner who ran the first marathon and then died after completing his run. Based on what you know of aerobic respiration and fermentation, why might Philippides have died?

His muscles may have produced toxic levels of lactic acid, causing his blood to become more acidic.

Some present-day bacteria use a system of anaerobic respiration characterized by an electron transport chain analogous to that found in aerobic organisms. Which of the following correctly characterizes the anaerobic electron transport chain?

It establishes a proton gradient between the cytoplasm and the extracellular fluid.

Which of the following correctly characterizes the F1 subunit of ATP synthase?

It is the catalytic unit that synthesizes ATP.

Which of the following best describes how ATP synthase converts the potential energy of the proton gradient to the chemical energy of ATP? Do protons flow through the Fo or F1?

Kinetic energy from the flow of protons is converted to the kinetic energy of rotation of the Fo subunit; the rotation of the Fo subunit leads to rotation of the F1 subunit, which can then catalyze ATP synthesis.

A researcher is comparing the amount of proteins contained in inner and outer mitochondrial membranes. What do you expect she will find?

The amount of proteins is greater in the inner membrane.

True or false: Although cellular respiration is typically thought of as an aerobic process, glycolysis itself is actually anaerobic.

True

True or false: Although glycolysis produces four molecules of ATP by substrate-level phosphorylation, the net gain of ATP for the cell is two molecules. This is due to the fact that glycolysis is—at first—endergonic.

True

True or false: The majority of organisms on Earth can carry out some form of glycolysis.

True

Which of the following statements is true regarding pyruvate oxidation? a. Pyruvate oxidation forms the same number of NADH (per glucose molecule) as glycolysis. b. Pyruvate oxidation ends with the oxidation of an acetyl group, which forms CO2. c. Pyruvate oxidation directly follows the citric acid cycle during cellular respiration. d. Like glycolysis, pyruvate oxidation is carried out in the mitochondria.

a. Pyruvate oxidation forms the same number of NADH (per glucose molecule) as glycolysis.

An important aspect of biology is that many proteins are used in several different processes. Which of the following protein complexes is used in both the electron transport chain and the citric acid cycle? a. complex I b. complex II c. complex III d. complex IV e. ATP synthase

b. complex II

How did the earliest organisms on Earth most likely produce ATP?

by glycolysis

A researcher is studying a population of bacteria that carry out the citric acid cycle, but do so in reverse. What statements are likely true of these bacteria? a. These bacteria will release CO2 as a waste product and will carry out cellular respiration within their mitochondria. b. These bacteria carry out cellular respiration in their mitochondria. c. An individual bacterium will produce most of its energy by means of the citric acid cycle. d. These bacteria will produce sugars from intermediates of the citric acid cycle. e. These bacteria will release CO2 as a waste product.

c. An individual bacterium will produce most of its energy by means of the citric acid cycle.

magine that a eukaryotic cell carries a mutation impairing its ability to phosphorylate glucose during glycolysis. What is a likely result of this mutation? a. Because phosphorylation stabilizes glucose, glucose would spontaneously form pyruvate. b. Without the phosphorylation of glucose, glycolysis would consist entirely of exergonic reactions. c. Glucose could move out of the cell, slowing cellular respiration. d. High (possibly toxic) levels of glucose would accumulate in the cell. e. More pyruvate would be formed at the end of glycolysis.

c. Glucose could move out of the cell, slowing cellular respiration.

Imagine that you exhale after a deep breath. Which of the following are you not exhaling? a. CO2 b. waste products of both pyruvate oxidation and the citric acid cycle c. waste products of glycolysis d. waste products of pyruvate oxidation e. waste products of the citric acid cycle

c. waste products of glycolysis

Cellular respiration is a series of _____ reactions

catabolic

An electron from NADH entering the electron transport chain would travel among components of the chain in what sequence?

complex I, coenzyme Q, complex III, cytochrome C, complex IV, oxygen

The inputs to glycolysis do not include: a. Pi. b. glucose. c. ADP. d. NADH. e. NAD+.

d. NADH.

Phosphorylating glucose during phase 1 of glycolysis:

destabilizes the glucose molecule so that it can be broken down in phase 2.

Which of the following statements is true regarding pyruvate and glucose? a. Glucose easily passes in and out of mitochondria, and can often be found in the mitochondrial matrix. b. Pyruvate is typically "trapped" in the intermembrane space of mitochondria, where it is oxidized to form acetyl-CoA. c. Glucose and pyruvate are remarkably similar in structure, with both molecules possessing a ring shape. d. Both glucose and pyruvate can feed directly into the citric acid cycle, although acetyl-CoA is the preferred reactant for this process. e. None of the other answer options is correct.

e. None of the other answer options is correct.

In which of the following organisms would you expect ethanol fermentation to occur? a. bacteria b. fungi c. animals d. plants e. fungi and plants

e. fungi and plants

During pyruvate oxidation, pyruvate is broken down into CO2 and an acetyl group. The CO2 is:

less energetic than the acetyl group

The chemical bonds of carbohydrates and lipids have high potential energy because:

many of these bonds are C—C and C—H bonds

The citric acid cycle takes place in the:

mitochondrial matrix.

The final electron acceptor of the electron transport chain is:

oxygen

A beer maker is using yeast to make his favorite brew. How does yeast produce ethanol?

through the reduction of acetaldehyde, derived from pyruvate

If you've ever learned about beer making, you may know that some people add fruit juice to their yeast mixtures. Why?

to provide glucose to the yeast