Biology 121 Ch 7 (launchpad)

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.

The loss of electrons is referred to as:

oxidation

The mitochondrial electron transport chain is part of

oxidative phosphorylation

A simplified overall equation for respiration is as follows: C6H12O6+ 6O2→6CO2+ 6H2O + energy In this reaction, we can say that _____is reduced and _____ is oxidized.

oxygen; glucose

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

payoff phase

In pyruvate oxidation, the electron donor is _____and the electron acceptor is _____.

pyruvate; NAD+

Which of the following describes the key reactions in fermenting beer, wine, or other alcoholic beverages?

reduction of acetaldehyde, derived from pyruvate

Which of the following summarizes the net final products of glycolysis?

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

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

two pyruvate molecules.

The immediate source of electrons for the electron transport chain is

NADH and FADH2.

Which statement is true regarding Earth's earliest organisms?

These organisms likely carried out fermentation and may have had rudimentary proton pumps.

Where does the F1subunit of ATP synthase get its energy to catalyze the synthesis of ATP?

from rotational energy provided by the flow of protons through the channel in the Fo subunit

In cellular respiration, oxygen:

gains electrons and is reduced

The storage carbohydrate in animals is ___________and in plants is __________.

glycogen; starch

Acetate is the starting point for synthesis of a cell's:

lipids

Which of the following is a net product of glycolysis?

2 pyruvate

Which choice correctly lists the approximate number of ATP produced by (1) metabolism of a 16-carbon fatty acid, (2) fermentation of a single glucose, and (3) aerobic respiration of a single glucose, in that order? For this calculation, you will need to know that each 2-carbon unit cleaved from the fatty acid yields one NADH and one FADH2, and the 2-carbon unit is added to coenzyme A to become acetyl-CoA, which is further metabolized by the citric acid cycle

108, 2, 32

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 CO2at the completion of aerobic respiration?

6

The conversion of the potential energy of a proton gradient to a form more useful to the cell is achieved by coupling the movement of protons down their electrochemical gradient with the synthesis of ATP. This coupling is made possible by:

ATP synthase.

Which of these reactions summarizes the overall reactions of cellular respiration

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

Some bacteria run the citric acid cycle in reverse. Without any other modifications to the cycle, what inputs would be required to do this?

CO2, FADH2, NADH, and ATP

What happens when glucose is phosphorylated during phase 1 of glycolysis?

Glucose is destabilized so that it can be broken apart in phase 2.

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? Please choose the correct answer from the following choices, and then select the submit answer button.

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

Which of the following is one explanation for why glycolysis is believed to have arisen very early in the evolution of life?

It does not require oxygen

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

When oxygen is depleted, the citric acid cycle stops. Which of the answer choices would you need to add to the system to restore activity? Select all that apply

NAD+, FAD

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

NADH

The majority of the energy captured in the citric acid cycle is in the form of

electrons donated to NAD+ and FAD.

Which statement is true regarding pyruvate and glucose?

Pyruvate can be transported across both membranes of the mitochondrion to be further metabolized, but glucose cannot.

Which statement is true regarding pyruvate oxidation?

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

Which statement is true regarding triacylglycerols?

The fatty acids from triacylglycerols are broken down to generate acetyl-CoA.

In the citric acid cycle, after the acetyl-group (2C) from acetyl-CoA is transferred to oxaloacetate (4C) to produce citrate (6C), subsequent reactions eventually result in 4C intermediates that are rearranged to regenerate oxaloacetate. What happens to the other two carbons?

They are released as CO2 byproducts.

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.

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

by glycolysis

A research group has discovered an organism with cells that contain a previously undescribed organelle. Researchers perform some tests on the isolated organelle to see if it is involved in any major metabolic reactions. To do this, they incubate these organelles for a period of time and determine changes in the amount of various substances in the suspending solution. The results are shown in the table.Based on this analysis, which metabolic process would you conclude could be taking place in this organelle?

citric acid cycle

The first phase of glycolysis requires the input of two ATP molecules. It is therefore:

endergonic

Fermentation produces nearly twice as much ATP as aerobic respiration, which explains why it is a preferred pathway for bacteria

false

Pyruvate oxidation produces a large amount of ATP through substrate-level phosphorylation.

false

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

false

The outer surface of the Fo subunit of ATP synthase must be _____ to be embedded in the membrane.

hydrophobic

On completion of either ethanol or lactic acid fermentation, the yield is only two ATP molecules per glucose molecule. The remaining chemical energy from the glucose is found primarily in:

lactic acid and ethanol.

During pyruvate oxidation, pyruvate is broken down into CO2and an acetyl group. The CO2is:

less energetic than the acetyl group

In glycolysis, ATP is synthesized by:

substrate-level phosphorylation

Which process produces the highest number of reduced electron carriers and thus the greatest potential for generating ATP?

the citric acid cycle

Conditions that reduce the strength of the proton gradient across the inner mitochondrial membrane slow the production of ATP by ATP synthase.

true

The majority of organisms on Earth can carry out some form of glycolysis.

true

When glucose is broken down in a cell, all of the energy it stores is not released simultaneously but is instead released in a stepwise process.

true

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

water