Biology 1 (Biology 1610) - CH.9 ("Cellular Respiration and Fermentation.")

At the beginning of glycolysis, which two enzymes catalyze glucose to glucose-6-phosphate?

1. Glucokinase: Only attaches to glucose if the body has high concentrations. 2. Hexokinase: Has a high affinity for glucose.

Explain an overview of glycolysis. What are the 3 main ideas?

1. Glucose (6 carbons) is broken down into 2 pyruvate (Both have 3 carbons) 2. Two ATPs are net generated. 3. The reduction (gaining of electrons) of 2 NAD+ to 2 NADH. (NADH can be used later on to produce more ATPs)

Explain/Teach the 4 steps of cellular respiration:

1. Glycolysis 2. Pyruvate oxidation 3. Citric Acid cycle/ Kreb's cycle/ TCA cycle 4. Phosphorylation oxidation

What are the 3 reactions/steps of oxidation of pyruvate?

1. Pyruvate's carboxyl group becomes fully oxidized and gives off as a molecule of CO2. 2. The remaining two-carbon fragment is oxidized and the electrons transferred to NAD+, storing energy in the form of NADH. 3. Coenzyme A (CoA) is attached via its sulfur atom to the two-carbon intermediate, forming acetyl CoA.

What is the maximum ATP yield per glucose?

30-32 ATP

What are the results of the citric acid cycle?

6 NADH 2 FADH2 2 GTP 4 CO2

The final electron acceptor of the electron transport chain that functions in aerobic oxidative phosphorylation is: A. O2. B. water. C. NAD+. D. pyruvate.

A

Under which conditions will plant cell mitochondria actively oxidize pyruvate and carry out oxidative phosphorylation? A. in all cells, with or without light B. in photosynthesizing cells in the light, and in other cells in the dark C. only in photosynthetic cells in the light, while photosynthesis occurs concurrently D. only in cells that store glucose in the form of starch and only in the dark

A

When electrons flow along the electron transport chains of mitochondria, which of the following changes occurs? A. The pH of the matrix increases. B. ATP synthase pumps protons by active transport. C. The electrons gain free energy. D. NAD+ is oxidized.

A

Which of the following events are associated with chemiosmosis in chloroplasts? A. The pH of the thylakoid space increases and ATP is synthesized. B. The pH of the stroma decreases and ATP is hydrolyzed. C. The pH of the cytosol outside the chloroplast decreases and ATP is synthesized. D. The pH of the stroma increases and ATP is synthesized.

A

Which of the following products result from the oxidation of pyruvate to acetyl-CoA? A. NADH and CO2 B. O2 and ATP C. FADH2 and CO2 D. NAD+, ATP and CO2

A

Which of the following reactions produces the majority of the CO2 released by the complete oxidation of glucose? A. the citric acid cycle B. glycolysis C. oxidation of pyruvate to acetyl-CoA D. electron transport

A

The electron transport chain makes no _________ directly. Instead, it eases the fall of electrons from food to oxygen, breaking a large free-energy drop into a series of smaller steps that release energy in manageable amounts, step by step.

ATP

Identify all correct statements about the basic function of fermentation. A. The basic function of fermentation is the production of additional ATP by further oxidation of the products of glycolysis. B. The basic function of fermentation is the regeneration of NAD+, which allows continued ATP production by glycolysis. C. The basic function of fermentation is the production of ethyl alcohol or lactic acid.

B

In cellular respiration, a series of molecules forming an electron transport chain alternately accepts and then donates electrons. What is the advantage of such an electron transport chain? A. The advantage of an electron transport chain is the production of a large number of reduced, high-energy intermediates. B. The advantage of an electron transport chain is that a small amount of energy is released with the transfer of an electron between each pair of intermediates. C. The advantage of the respiratory electron transport chain is that oxygen is the final electron acceptor.

B

In mitochondria, exergonic redox reactions: A. are the source of energy driving prokaryotic ATP synthesis. B. provide the energy that establishes the proton gradient. C. reduce carbon atoms to carbon dioxide. D. are coupled via phosphorylated intermediates to endergonic processes.

B

Most CO2 from catabolism is released during: A. glycolysis. B. the citric acid cycle. C. lactate fermentation. D. electron transport.

B

Select the correct statement about cellular respiration. A. Plants carry out cellular respiration only in organs such as roots that cannot carry out photosynthesis. B. Cellular respiration and breathing differ in that cellular respiration is at the cellular level, whereas breathing is at the organismal level. C. Animals carry out cellular respiration whereas plants carry out photosynthesis.

B

When a cell is deprived of oxygen, which of the following processes will be inhibited first? A. the citric acid cycle B. the electron transport chain C. the oxidation of pyruvate to acetyl CoA D. glycolysis

B

Which of the following best predicts the effect of removal of oxygen from a facultative anaerobic organism's environment? A. glucose consumption and the growth rate both increase B. glucose consumption increases, while the growth rate decreases C. glucose consumption decreases, while the growth rate increases D. glucose consumption decreases, while the growth rate remains unchanged

B

Which of the following events takes place in the electron transport chain? A. the breakdown of an acetyl group to carbon dioxide B. the harnessing of energy from redox reactions to generate a proton gradient C. substrate-level phosphorylation D. the breakdown of glucose into six carbon dioxide molecules

B

Which of the following statements about the citric acid cycle is correct? A. The citric acid cycle produces most of the ATP that is subsequently used by the electron transport chain. B. The last reaction in the citric acid cycle produces a product that is a substrate for the first reaction of the citric acid cycle. C. The citric acid cycle depends on the availability of NAD+, which is a product of glycolysis. D. The citric acid cycle oxidizes glucose to carbon dioxide. E. The oxidation of compounds by the citric acid cycle requires molecular oxygen.

B

Which of the following statements best describes what happens to a molecule of NAD+ (nicotinamide adenine dinucleotide) when it gains a hydrogen atom? A. NAD+ becomes oxidized. B. NAD+ becomes reduced. C. NAD+ becomes dehydrogenated. D. NAD+ becomes ionized.

B

Which of the following types of metabolic poison would most directly interfere with glycolysis? A. an agent that binds to pyruvate and inactivates it B. an agent that closely mimics the structure of glucose but is not metabolized C. an agent that reacts with NADH and oxidizes it to NAD+ D. an agent that reacts with oxygen and depletes its concentration in the cell

B

Which of the summary statements below best describes the results of the following reaction? C6H12O6 + 6O2 →→ 6CO2 + 6H2O + Energy A. CO2 is reduced and O2 is oxidized. B. C6H12O6 is oxidized and O2 is reduced. C. O2 is reduced and CO2 is oxidized. D. O2 is oxidized and H2O is reduced.

B

Which one of the following statements about the redox reactions of the electron transport chain is correct? A. NADH gains electrons in the initial reaction of the electron transport chain. B. The redox reactions of the electron transport chain are directly coupled to the movement of protons across a membrane. C. The electron transport chain takes electrons from water and gives them to oxygen. D. The oxidation of NADH is directly coupled to the reduction of oxygen to water. E. The redox reactions of the electron transport chain are directly coupled with the synthesis of ATP.

B

Exposing inner mitochondrial membranes to ultrasonic vibrations will fragment the membranes and pieces will reseal "inside out" to form small vesicles. The fact that these vesicles can transfer electrons from NADH to oxygen and synthesize ATP suggests that which of the following components must be present? A. only the electron transport system B. only the ATP synthase system C. all of the electron transport system and ATP synthase D. all of the electron transport system and the proteins that add CoA to acetyl groups

C

In the absence of oxygen, yeast cells can obtain energy by fermentation, which results in the net production of which of the following sets of molecules? A. ATP, NADH, and ethanol B. ATP, CO2, and lactate C. ATP, CO2, and ethanol D. ATP, CO2, and acetyl CoA

C

Step 3 is a major point of regulation of glycolysis. The enzyme phosphofructokinase is allosterically regulated by ATP and related molecules. Considering the overall result of glycolysis, would you expect ATP to inhibit or stimulate activity of this enzyme? (Hint: Make sure you consider the role of ATP as an allosteric regulator, not as a substrate of the enzyme.) A. The overall process of glycolysis results in net production of ATP. Thus, we would expect ATP to allosterically stimulate phosphofructokinase. B. The overall process of glycolysis results in net production of NADH and pyruvate while using ATP. Thus, we would expect ATP to allosterically stimulate phosphofructokinase. C. The overall process of glycolysis results in net production of ATP. Thus, we would expect ATP to allosterically inhibit phosphofructokinase. D. The overall process of glycolysis results in net production of NADH and pyruvate while using ATP. Thus, we would expect ATP to allosterically inhibit phosphofructokinase.

C

The immediate energy source that drives ATP synthesis by ATP synthase during oxidative phosphorylation is the: A. oxidation of glucose and other organic compounds. B. flow of electrons down the electron transport chain. C. H+ concentration gradient across the membrane holding ATP synthase. D. transfer of phosphate to ADP.

C

What types of cells carry out ATP synthesis by chemiosmosis? A. only animal cells in mitochondria, exclusively using oxygen as the electron acceptor B. all cells, both prokaryotic and eukaryotic, exclusively using oxygen as the electron acceptor C. all respiring cells, both prokaryotic and eukaryotic, using either oxygen or other electron acceptors D. only eukaryotic cells, both plant and animal, using either oxygen or other electron acceptors

C

Which metabolic pathway is common to both fermentation and cellular respiration of a glucose molecule? A. the citric acid cycle B. the electron transport chain C. glycolysis D. reduction of pyruvate to lactate

C

Which of the following molecules is the lowest-energy donor of electrons to the electron transport chain? A. NADH B. water C. FADH2 D. ATP

C

Which of the following statements accurately describes the function of a metabolic pathway involved in cellular respiration? A. The function of the bonding of acetic acid to the carrier molecule CoA to form acetyl CoA is the reduction of glucose to acetyl CoA. B. The function of the citric acid cycle is the transfer of electrons from pyruvate to NADH to O2. C. The function of glycolysis is to begin catabolism by breaking glucose into two molecules of pyruvate, with a net yield of two ATP.

C

Which of the following statements best describes the electron transport chain? A. It includes a series of hydrolysis reactions associated with mitochondrial membranes. B. It is driven by ATP hydrolysis. C. It consists of a series of redox reactions. D. It occurs in the cytoplasm of both prokaryotic and eukaryotic cells.

C

Which of the following statements best explains why carbohydrates and fats may be considered high-energy foods? A. They contain no low-energy nitrogen atoms. B. They contain many protons associated with oxygen atoms. C. They contain many electrons associated with hydrogen atoms. D. They are strong oxidizing molecules.

C

What is the difference between catabolism and anabolism?

Catabolism: Breaking down molecules. (polymers --> monomers) Anabolism: Building up molecules. (monomers --> polymers)

Depletion of which of the following molecules from the mitochondria will most directly inhibit the citric acid cycle? A. CO2 B. NADH C. ATP D. NAD+

D

If pyruvate oxidation is blocked, what is the most likely effect on the levels of oxaloacetate and citrate in the citric acid cycle shown in the accompanying figure? A. Both oxaloacetate and citrate will accumulate. B. Oxaloacetate will decrease and citrate will accumulate. C. Both oxaloacetate and citrate will decrease. D. Oxaloacetate will accumulate and citrate will decrease.

D

The enzyme phosphofructokinase (PFK) catalyzes a key step in glycolysis and is inhibited by high levels of which of the following molecules? A. citrate and CO2 B. AMP and ATP C. glucose and NAD+ D. ATP and citrate

D

What is the oxidizing agent in the following reaction? Pyruvate+NADH+H+ →Lactate+NAD+ A. oxygen B. NADH C. lactate D. pyruvate

D

When electrons flow along the electron transport chains of mitochondria, which of the following changes occurs? A. NAD+ is oxidized. B. ATP synthase pumps protons by active transport. C. The electrons gain free energy. D. The pH of the matrix increases.

D

How do electrons that are extracted from glucose and stored as potential energy in NADH finally reach oxygen?

Electron transport chain: Electrons removed from glucose are shuttled by NADH to the "top," higher-energy end of the chain. At the "bottom," lower-energy end, O2 captures these electrons along with hydrogen nuclei (H+), forming water.

What is the difference between an exergonic and endergonic reaction?

Exergonic: releases energy and is always spontaneous. Endergonic: Takes in energy and is always non spontaneous.

The enzyme that converts fructose-6-phosphate to Fructose-1,6-Biphosphate is called what?

Phosphofructokinase-1 (PFK1) - Rate Limiting enzyme

What will promote and inhibit the enzyme PFK1?

Promote: AMP Inhibit: ATP, Citrate

What is the goal of the citric acid cycle?

To generate NADH and FADH2 molecules so that those molecules can leave the citric acid cycle and go to another biochemical pathway known as the electron transport chain to generate the most amount of ATP.

What is the function of Hexokinase in glycolysis?

Transfers a phosphate group from ATP to glucose, making it more chemically reactive. (The charged phosphate also traps the sugar in the cell.)

When O2 is present, the pyruvate in eukaryotic cells enters a ____________________, where the oxidation of glucose is completed.

mitochondrion

Acetyl-CoA enters the citric acid cycle in the mitochondrion by combining with ___________________ to form citrate.

oxaloacetate

In a redox reaction, the loss of electrons from one substance is called _______________, and the addition of electrons to another substance is known as ______________.

oxidation, reduction (Note that adding electrons is called reduction; adding negatively charged electrons to an atom reduces the amount of positive charge of that atom.)

The final and ultimate acceptor in the electron transport chain is _____________.

oxygen

A single molecule of NADH generates enough proton-motive force for the synthesis of ______ ATP.

2.5

Energy released from the electron transport chain is used to pump H+ ions into which location in eukaryotic cells? A. cytoplasm adjacent to the mitochondrial outer membrane B. mitochondrial intermembrane space C. mitochondrial inner membrane D. mitochondrial matrix

B

___________________ is a way of harvesting chemical energy without using either O2 or any electron transport chain—in other words, without cellular respiration.

Fermentation

NADH electrons go where? FADH2 electrons go where?

NADH ---> NAD+ ---> Electrons ---> Complex I ---> CoQ ---> Complex III ---> CytC ---> Complex IV ---> O2 (Two hydrogens are added making H2O) FADH2 ---> FAD ---> Electrons ---> Complex II ---> CoQ ---> Complex III ---> CytC ---> Complex IV ---> O2 (Two hydrogens are added making H2O)

In the generalized reaction, which substance is the reducing agent and which substance is the oxidizing agent?

Reducing agent: The electron donor. Oxidizing agent: The electron acceptor.

_________________ is the transfer of an electron from a donor to an acceptor, where the acceptor is O2.

Respiration

What is a collection of molecules embedded in the inner membrane of the mitochondrion in eukaryotic cells?

The electron transport chain

During ATP energy is ____________ and during ADP energy is _____________.

stored, released. (The less amount of energy is stored in the ADP molecule as it contains only two molecules of phosphate, while a large amount of energy is stored in ATP as it consists of three molecules of phosphate.)

The word glycolysis means: "__________ _____________."

sugar splitting

Glycolysis can be broken down into two phases, what are they?

1. Energy investment phase. (The cell actually spends ATP) 2. Energy payoff phase.

NADH only works at complex ____ and FADH2 only works at complex ____ of the electron transport chain.

Complex 1, complex 2