Chapter 7 Biology

What would be the ATP yield for a molecule that is catabolized to form one molecule of pyruvate in a eukaryotic cell?

12.5 ATP

What is the net number of ATP generated directly during glycolysis per molecule of glucose?

2

What are the products of one turn of the Krebs cycle?

2 CO2, 3 NADH, 1 FADH2, 1 ATP

If you take into account the amount of ATP generated by ATP synthase per molecule of NADH and per molecule of FADH2 produced, and the number of ATP molecules produced by substrate-level phosphorylation, what is the predicted energy yield of the Krebs cycle, per molecule of glucose in eukaryotic cells?

20 ATP

How many oxidation reactions occur during the Krebs cycle?

3

. If you take into account the amount of ATP generated by ATP synthase per molecule of NADH produced in aerobic respiration, the net number of ATP molecules produced by substrate-level phosphorylation, and the fact that NADH molecules produced in the cytoplasm have to be transported into the mitochondria, what is the predicted energy yield of glycolysis in eukaryotic cells?

5 ATP

Cardiac muscle cells need to generate significant amounts of ATP to allow for constant contractile activity. As a result, they primarily depend upon beta-oxidation of fatty acids, which has a higher energy yield than the catabolism of glucose. What would be the ATP yield for beta-oxidation of a hypothetical 10-carbon fatty acid?

62 ATP

When substrate-level phosphorylation occurs, it means that:

ADP is converted into ATP by the addition of a phosphate group.

How and where is ATP made in a eukaryotic cell?

ATP can be made by direct phosphorylation of ADP in the cytoplasm, and by an enzyme complex that uses the energy from a proton gradient to drive ATP synthesis in the mitochondria. It can also be made in other locations in the cell, depending on the cell type.

. One way to generate acetyl-CoA is to convert pyruvate into acetyl-CoA by stripping off a C02 molecule. The removal of CO2 is referred to as what type of reaction?

Decarboxylation

In the reaction: C4H6O4 + FAD C4H4O4 + FADH2, what type of reaction took place to remove the protons from C4H6O4?

Dehydrogenation

To form NADH from NAD+, two electrons and a proton are removed from an organic molecule. What term best describes the reaction in which electrons and a proton are removed from an organic molecule?

Dehydrogenation

The equation for cellular respiration is: C6H12O6 + 6O2 6CO2 + 6H2O. At what specific point in the cellular respiration process has glucose been broken down completely from a six carbon molecule to 6 molecules of CO2?

During the second oxidation in the Krebs cycle

During what step of glycolysis are two ATP molecules required?

Glucose priming

It is thought that the oldest stage of cellular respiration from an evolutionary perspective is:

Glycolysis

This process is common to all living cells:

Glycolysis

What aspect of cellular respiration occurs in the cytoplasm in eukaryotic cells?

Glycolysis

What stage of cellular respiration can occur in human cells with or without oxygen present?

Glycolysis

When oxygen is unavailable during heavy exercise what process do muscle cells use for energy generation?

Glycolysis coupled with lactate fermentation

If citrate levels are high in the cell, but ATP levels are low, what do you think will happen in the cell?

Glycolysis will be inhibited, but the Krebs cycle will be functional, allowing it to be utilized to breakdown acetyl-CoA generated from beta-oxidation.

Organisms that depend on the energy stored in chemical bonds by other organisms for their food energy are called ____________.

Heterotrophs

What is different about the way that NADH and FADH2 donate electrons to the electron transport chain?

NADH contributes its electrons to the first transmembrane complex in the electron transport chain and FADH2 contributes its electrons after the first transmembrane complex.

If ATP synthase had a mutation in the F1 complex portion of the protein, what function of ATP synthase would most likely be affected?

The conversion of ADP and Pi to ATP.

Cytochromes contain a heme group similar to that in hemoglobin. The iron atom (Fe) in the center of the group can be oxidized and reduced. If someone was suffering from iron deficiency anemia, what stage of cellular respiration would be most affected?

The electron transport chain

As electrons move along the electron transport chain, they lose potential energy. How is the energy that is released used by the cell?

The energy is used to transport protons against their concentration gradient

As a forensic pathologist, you have just completed an autopsy of a poisoning victim. After a thorough examination, you conclude that the victim died of cyanide poisoning. You know that cyanide binds to the cytochrome oxidase complex, and therefore list the official cause of death as suffocation due to cyanide exposure. However, if you wanted to provide a more technical explanation as to the cause of death, what process was specifically inhibited directly by cyanide?

The formation of water from oxygen

. All of the reactions of cellular respiration that occur after glycolysis take place in what part of the eukaryotic cell?

The mitochondria

Arsenic poisoning can lead to organ failure and death. Though arsenic can inhibit or interfere with a number of cellular enzymes, arsenic poisoning is thought to be mainly due to indirect inhibition of enzymes involved in both pyruvate oxidation and the Krebs cycle. As a result, this compound must be able to enter what cellular compartment?

The mitochondrial matrix

What is common to all of the oxidation reactions in the Krebs cycle?

They are all characterized by a loss of electrons from an organic molecule coupled to the reduction of an electron acceptor.

What must happen to amino acids before they can be used in catabolic reactions?

They must be deaminated

In the absence of oxygen, can cells utilize the electron transport chain?

Yes, in the case that a cell can use a terminal electron acceptor other than oxygen, it can make use of the electron transport chain.

Your friend is having difficulty keeping track of the energy flow from glucose through glycolysis, the Krebs cycle and electron transport. Your best advice would be to:

follow the electrons

Why is the energy generated from the catabolism of sugars and other macromolecules ultimately harnessed to generate ATP?

ATP can be used by cells to drive endergonic reactions

What molecule can oxidize NADH?

Acetaldehyde

Glucose is not our only food source, nor the only one we can utilize in our bodies to generate energy. Other primary sources of energy include other sugars, proteins, and fats. What metabolic intermediate are fats primarily converted into?

Acetyl-CoA

What important metabolic intermediate does not cross the inner membrane of the mitochondria?

Acetyl-CoA

13. A human cell has a mutation in the gene that encodes the enzyme that generates lactate from pyruvate, rendering that enzyme completely non-functional. Assuming that there is ample glucose present, how would this cell generate energy in the presence of oxygen?

Aerobic respiration

In animals that take in oxygen from their environment, glucose is broken down into carbon dioxide and water in a process called:

Aerobic respiration

Many of the antiviral drugs currently used to treat HIV/AIDS also interfere with an enzyme that helps mitochondria multiply. Treatment can therefore result in a decrease in the number of mitochondria found in certain tissues. Given this information, what might you expect to see in patients treated with antiviral drugs?

An increase in lactic acid levels

Where does pyruvate oxidation occur in eukaryotic cells?

In the mitochondria

The energy released in the mitochondrial electron transport chain is used to transport protons where?

Into the intermembrane space of the mitochondria

In the reaction catalyzed by aconitase, the conversion of citrate to isocitrate is inhibited by fluoroacetate. Fluoroacetate is used as a pesticide. Why is this an effective pesticide?

It inhibits the Krebs cycle

What happens to the oxygen that is used in cellular respiration?

It is reduced to form water

Regardless of the electron or hydrogen acceptor used, one of the products of fermentation is always:

NAD+

What is the oxidized form of the most common electron carrier that is needed for both glycolysis and the Krebs cycle?

NAD+

What oxidizing agent is used to temporarily store high energy electrons harvested from glucose molecules in a series of gradual steps in the cytoplasm?

NAD+

Many types of cancer cells have been detected to secrete significant levels of lactate. Do you think these cells are likely undergoing beta-oxidation?

No, because if lactate is being produced, the cell is not likely making use of the pathways needed to make use of the products of beta-oxidation.

Aerobic respiration involves the transfer of many electrons from glucose to electron carriers such as NAD+ over a series of multiple steps. Ultimately though, it is the reaction of glucose with oxygen to generate carbon dioxide, water and energy. Why doesn't glucose react directly with oxygen in cells?

Oxygen cannot accept electrons, and thus an electron carrier like NAD+ is needed.

In glycolysis, a major portion of the energy remains in the final product, which is called:

Pyruvate

What is an end-product of glycolysis?

Pyruvate

When amino acids are degraded in cells, into what intermediate(s) of the aerobic respiration process are the carbon skeletons of amino acids primarily converted?

Pyruvate and Krebs cycle intermediates

You decide to go on vacation in the mountains, where you are staying in a cabin. Unfortunately, when you turn on the water in the cabin you smell hydrogen sulfide (H2S) gas. After some research, you find out that the H2S may be due to the presence of sulfur bacteria living in your pipes. What molecule do these bacteria use as an electron acceptor?

SO4

In aerobic respiration, chemiosmotic generation of ATP is driven by:

a difference in H+ concentration on the two sides of the inner mitochondrial membrane.