MCB 181 Pre class assignment 19

Which stages of cellular respiration use O2 as an input?

oxidative phosphorylation

Most of the ATP produced during cellular respiration is generated through:

oxidative phosphorylation.

The mitochondrial electron transport chain is part of:

oxidative phosphorylation.

During the metabolism of glucose (the cellular fuel molecule) by the process of aerobic cellular respiration, glucose is _____ to CO2 via _____ reactions.

oxidized; redox

A molecule that is _____ loses electrons, and a molecule that is _____ gains electrons.

oxidized; reduced

Which stages of cellular respiration produce CO2 as a waste product?

pyruvate oxidation and the citric acid cycle

At the end of glycolysis, the carbon originally found in the starting glucose molecule is now present in:

two pyruvate molecules.

In the electron transport chain, the energy from high‐energy electrons is transformed into ______ before being used to generate ATP.

a proton gradient

Energy released by transferring electrons along the electron transport chain is stored as potential energy in the form of:

a proton gradient.

During glycolysis, pyruvate oxidation, and the citric acid cycle, the chemical energy in glucose is transferred to:

electron carriers and ATP.

In a plant cell, the oxidative phosphorylation stage of cellular respiration is carried out in the cytoplasm.

false

The glycolysis stage is responsible for producing most of the ATP during cellular respiration.

false

Certain complexes of the mitochondrial electron transport chain pump protons. Protons are pumped across the _____ mitochondrial membrane, from the _____ to the _____ .

inner; matrix; intermembrane space

Which example represents the reduced forms of the two major electron carriers?

NADH and FADH2

The immediate source of electrons for the electron transport chain is:

NADH and FADH2.

In oxidation‐reduction reactions (redox reactions), _____ are _____ during reduction.

electrons; gained

Most of the proteins of the electron transport chain are:

embedded in the inner mitochondrial membrane

Which summary sequence correctly tracks electrons through the overall process of aerobic cellular respiration?

glucose → electron carriers → electron transport chain → water

During which phase(s) of glycolysis do we observe pyruvate production, ATP synthesis, and reduction of NAD+?

payoff phase

During the important redox reactions of electron transport chain, the transfer of electrons is typically accompanied by transfer of:

protons.

What glycolysis products are transported into the mitochondria? Select all that apply.

pyruvate NADH

Which stage of cellular respiration occurs following production of pyruvate?

pyruvate oxidation

Acetyl‐CoA synthesis occurs during:

pyruvate oxidation.

The energy in organic molecules is released in a series of steps rather than a single step because:

the amount of energy released would be too much to capture in one reaction.

In eukaryotic cells, glycolysis occurs in:

the cytoplasm.

During the pyruvate oxidation stage of cellular respiration, what occurs?

the formation of NADH the formation of CO2 the formation of acetyl‐CoA the oxidation of pyruvate

In eukaryotic cells, the oxidation of pyruvate occurs in:

the matrix of the mitochondria.

Cellular respiration is a series of _____ reactions.

catabolic

What is a product (as opposed to a substrate) of at least one of the processes of cellular respiration?

water

Tracing the metabolism of one glucose molecule, how many carbon atoms are fully oxidized to CO2 at the completion of glycolysis?

0

How many reactions in glycolysis directly generate ATP by substrate‐level phosphorylation?

2

Tracing the metabolism of one glucose molecule, how many carbon atoms are available for further oxidation at the completion of the pyruvate oxidation stage?

4

Tracing the metabolism of one glucose molecule, how many carbon atoms are fully oxidized to CO2 at the completion of aerobic respiration?

6

Which best describes energy captured in ATP during aerobic cellular respiration?

A small amount of energy is captured in ATP by substrate‐level phosphorylation; most is captured in ATP by oxidative phosphorylation.

Complete oxidation of glucose to CO2 involves two different mechanisms for synthesizing ATP: oxidative phosphorylation and substrate‐level phosphorylation. Which is true of substrate‐level phosphorylation?

An enzyme catalyzes the transfer of a phosphate group from an organic molecule to ADP to form ATP.

Which of these reactions summarizes the overall reactions of cellular respiration?

C6H12O6 + 6 O2 → 6 CO2 + 6 H2O + energy

During the citric acid cycle, which is shown, what happens to the coenzyme A that is part of acetyl‐CoA?

It is recycled for use in other reactions.

What product of the pyruvate oxidation stage of cellular respiration will have the two electrons that are lost from pyruvate?

NADH

Which of the answer choices are direct sources of electrons for the electron transport chain? Select all that apply.

NADH FADH2

Glycolysis is a series of chemical reactions (endergonic and exergonic) by which the cell can obtain ATP. NAD+ plays a crucial role in the reactions of glycolysis by:

accepting electrons during glycolysis, with the overall result that glucose is partially oxidized to pyruvate.

Each round of the citric acid cycle begins when the four‐carbon molecule oxaloacetate is converted to the six‐carbon molecule citrate. As the cycle progresses, two carbons are eliminated to regenerate the oxaloacetate. The added carbon is supplied by _____ and the two eliminated carbons are released as _____ .

acetyl‐CoA; CO2

Animals breathe in air containing oxygen and breathe out air containing less oxygen. The consumed oxygen is used:

as an electron acceptor in the respiratory electron transport chain.

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

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

many of these bonds are C-C and C-H bonds, in which electrons are shared equally between atoms.

Although glycolysis produces four molecules of ATP by substrate‐level phosphorylation, the net gain of ATP for the cell is two molecules. This is because:

two molecules are used in the initial stage.

Which example summarizes the net final products of glycolysis?

two molecules of pyruvate, two molecules of ATP, and two molecules of NADH