mastering bio ch 5&9

How would anaerobic conditions (when no O2 is present) affect the rate of electron transport and ATP production during oxidative phosphorylation? (Note that you should not consider the effect on ATP synthesis in glycolysis or the citric acid cycle.)

Both electron transport and ATP synthesis would stop

Compare and contrast substrate-level phosphorylation and oxidative phosphorylation.What do they have in common?

Both processes produce ATP from ADP and Pi.

Glycogen is _____.

a polysaccharide found in animals

Which of the following classes of macromolecules always contains a carbohydrate portion?

nucleic acids

In glycolysis, as in all the stages of cellular respiration, the transfer of electrons from electron donors to electron acceptors plays a critical role in the overall conversion of the energy in foods to energy in ATP. These reactions involving electron transfers are known as oxidation-reduction, or redox, reactions.

1. When a compound donates (loses) electrons, that compound becomes oxidized. Such a compound is often referred to as an electron donor. 2. When a compound accepts (gains) electrons, that compound becomes reduced. Such a compound is often referred to as an electron acceptor. 3. In glycolysis, the carbon-containing compound that functions as the electron donor is glucose. 4. Once the electron donor in glycolysis gives up its electrons, it is oxidized to a compound called pyruvate. 5. NAD+ is the compound that functions as the electron acceptor in glycolysis. 6. The reduced form of the electron acceptor in glycolysis isNADH.

The rate of cellular respiration is regulated by its major product, ATP, via feedback inhibition. As the diagram shows, high levels of ATP inhibit phosphofructokinase (PFK), an early enzyme in glycolysis. As a result, the rate of cellular respiration, and thus ATP production, decreases. Feedback inhibition enables cells to adjust their rate of cellular respiration to match their demand for ATP.

ATP levels would fall at first, decreasing the inhibition of PFK and increasing the rate of ATP production.

NADH and FADH2 are both electron carriers that donate their electrons to the electron transport chain. The electrons ultimately reduce O2 to water in the final step of electron transport. However, the amount of ATP made by electrons from an NADH molecule is greater than the amount made by electrons from an FADH2 molecule.

Fewer protons are pumped across the inner mitochondrial membrane when FADH2 is the electron donor than when NADH is the electron donor.

Cellular locations of the four stages of cellular respiration

Glycolysis - Cytosol Acetyl CoA - Mitochondrial matrix Citric acid cycle - Mitochondrial matrix Oxidative phosphorylation - inner mitochondrial membrane

Under anaerobic conditions (a lack of oxygen), the conversion of pyruvate to acetyl CoA stops. Which of these statements is the correct explanation for this observation?

In the absence of oxygen, electron transport stops. NADH is no longer converted to NAD+, which is needed for the first three stages of cellular respiration. (NAD+ couples oxidative phosphorylation to acetyl CoA formation. The NAD+ needed to oxidize pyruvate to acetyl CoA is produced during electron transport. Without O2, electron transport stops, and the oxidation of pyruvate to acetyl CoA also stops because of the lack of NAD+. )

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.

What would happen to the proton gradient and ATP production after a drug has poisoned the enzyme that combines acetyl CoA and oxaloacetate to form citrate?

Less NADH production would create to a weaker proton gradient and less ATP production.

From the following compounds involved in cellular respiration, choose those that are the net inputs and net outputs of glycolysis.

Net Input: ADP, NAD⁺, Glucose Net Output: ATP, NADH and Pyruvate, not input or output: O₂, CO₂, coenzyme A and acetyl CoA

In the citric acid cycle (also known as the Krebs cycle), acetyl CoA is completely oxidized. From the following compounds involved in cellular respiration, choose those that are the net inputs and net outputs of the citric acid cycle.

Net Input: Acetyl CoA, NAD⁺, ADP Net Output: Coenzyme A, CO₂, NADH, ATP Not Input or Output: Pyruvate, Glucose, O₂

In the last stage of cellular respiration, oxidative phosphorylation, all of the reduced electron carriers produced in the previous stages are oxidized by oxygen via the electron transport chain. The energy from this oxidation is stored in a form that is used by most other energy-requiring reactions in cells. From the following compounds involved in cellular respiration, choose those that are the net inputs and net outputs of oxidative phosphorylation.

Net Input: NADH, ADP, O₂ Net Output: NAD⁺, ATP, CO₂ and Water Not Input or Output: Pyruvate, Glucose, Acetyl CoA, Coenzyme A and CO₂.

In acetyl CoA formation, the carbon-containing compound from glycolysis is oxidized to produce acetyl CoA. From the following compounds involved in cellular respiration, choose those that are the net inputs and net outputs of acetyl CoA formation.

Net Input: NAD⁺, coenzyme A, pyruvate Net Output: NADH, acetyl CoA, CO₂ not input or output: O₂, ADP, glucose and ATP

Compare and contrast substrate-level phosphorylation and oxidative phosphorylation. What are their differences?

Substrate-level phosphorylation occurs when enzymes remove a high-energy phosphate from a substrate and directly transfer it to ADP occurs under the action of pyruvate kinase and phosphoglycerate kinase Oxidative phosphorylation occurs when electrons move through an ETC and produce a proton-motive force that drives ATP synthase occurs under the action of ATP synthase

Which of the following statements correctly identifies why fermentation alone won't keep cells alive.?

The oxidation of glucose via cellular respiration has the potential yield of 29 ATP while the oxidation of glucose via fermentation yields only 2 ATP.

The energy of electron transport serves to move (translocate) protons to the outer mitochondrial compartment. How does this help the mitochondrion produce ATP?

The translocation of protons sets up the electrochemical gradient that drives ATP synthesis in the mitochondria.

Which statement most accurately describes how the carbohydrates you ate during breakfast today are functioning in your body right now?

They are storing chemical energy, indicating cell identity, and serving as raw material for synthesizing other molecules.

Why are fermentation reactions important for cells?

They regenerate NAD+ so that glycolysis can continue to operate.

Which statement best describes what happens during the redox reaction between NADH and Complex I of the electron transport chain?

Which statement best describes what happens during the redox reaction between NADH and Complex I of the electron transport chain?

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

accepting electrons at the end of the electron transport chain

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

all cells all the time

Starch and cellulose _____.

are polymers of glucose

Which of these is a polysaccharide?

cellulose

most abundant organic compound on Earth.

cellulose

During pyruvate processing, two carbons from pyruvate combine with ____.

coenzyme A

The ATP that is generated in glycolysis is produced by substrate-level phosphorylation, a very different mechanism than the one used to produce ATP during oxidative phosphorylation. Phosphorylation reactions involve the addition of a phosphate group to another molecule.

correct: An enzyme is required in order for the reaction to occur. A bond must be broken between an organic molecule and phosphate before ATP can form. One of the substrates is a molecule derived from the breakdown of glucose. Incorrect: The enzymes involved in ATP synthesis must be attached to a membrane to produce ATP. The phosphate group added to ADP to make ATP comes from free inorganic phosphate ions.

Which metabolic pathway is common to both cellular respiration and fermentation?

glycolysis

What type of bond is formed between two sugars in a disaccharide?

glycosidic linkage

C6H12O6 (glucose) + 6 O2 → 6 CO2 + 6 H2O Where is most of the water in this reaction produced?

in the electron transport chain

Where does the citric acid cycle occur in eukaryotes?

in the matrix of mitochondria

glucose + glucose —> _____ by _____.

maltose + water ... dehydration synthesis

Energy released by the electron transport chain is used to pump H+ into which location in eukaryotic cells?

mitochondrial intermembrane space

During cellular respiration, acetyl CoA accumulates in which location?

mitochondrial matrix

Net redox reaction in acetyl CoA formation and the citric acid cycle. In the sequential reactions of acetyl CoA formation and the citric acid cycle, pyruvate (the output from glycolysis) is completely oxidized, and the electrons produced from this oxidation are passed on to two types of electron acceptors.

pyruvate is oxidized to (a) CO2 NAD+ is reduced to (b) NADH (c) FAD is reduced to (d)FADH2

Among the products of glycolysis, which compounds contain energy that can be used by other biological reactions?

pyruvate, ATP, and NADH

Glycolysis is a series of ___ reactions that occurs in the _____ of cells.

ten; cytoplasm

In mitochondrial electron transport, what is the direct role of O2?

to function as the final electron acceptor in the electron transport chain

For each molecule of glucose processed during glycolysis, the net yield is ____.

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