Portage Biochemistry- Module 7

A scientist uses the term flux regarding a biochemical pathway. What does flux mean?

Flux is the rate of flow through a biochemical pathway.

A particular pathway breaks down proteins into amino acids. Is this an anabolic or a catabolic pathway?

Catabolic. This is degradation of a molecule.

The acetyl group is connected to CoA to make Acetyl-CoA. A) What specific atom of CoA connects to the carbon atom on the acetyl group? B) What nucleotide base is part of CoA?

A) Sulfur B) Adenine

Both carbohydrates and lipids are broken down into Acetyl-CoA for further processing. What pathway does Acetyl-CoA go to next?

Citric Acid Cycle (CAC)

What is the "ETC" and what happens there?

Electron transport chain. NADH is converted into ATP at the ETC.

What is the sign (+ or -) of ΔG for the breakdown of ATP to ADP? Why is the sign important?

(-). A negative means spontaneous, or favorable, and is able to power other processes.

What molecule (FADH2, ATP, ADP, or CoA) is shown below?

ADP

What are the two phases of glycolysis? How many reactions in each?

The preparatory phase and payoff phase. Five reactions in each.

How many ATPs are invested in glycolysis?

2

What is the net number of ATP gained from glycolysis?

2 (2 invested, 4 gained, for a net of 2)

How many reactions of glycolysis have a single arrow "→" in their reaction equation?

3

What is the fate of pyruvate produced in glycolysis?

Under anaerobic conditions, it goes to lactate or sometimes ethanol or other products to regenerate NAD+ for glycolysis. Under aerobic conditions, it proceeds to the citric acid cycle.

For one molecule of glyceraldehyde-3-phosphate, how many ATP or NADH are produced (or required) in the glyceraldehyde-3-phosphate to 1,3-bisphosphoglycerate step in glycolysis?

1 NADH required

1 NADH produced

2 ATP produced

You Answered 1 ATP required

None of the above

1 NADH produced

Fill in the appropriate blanks in the following sentence using the word bank. All words will not be used; words can be used more than once.

Word (phrase) bank:

Reaction 3

Reaction 6

Reaction 7

Reaction 10

Fructose-6-phosphate

1,3-bisphosphoglycerate

Glyceraldehyde-3-phosphate

Pyruvate

In ____(A)_____, phosphate from _____(B)_______ is transferred to ADP and yields ATP.

In ___(C)____, phosphate from ATP is transferred to ____(D)_______ forming ADP .

A) reaction 7

B) 1,3-bisphosphoglycerate

C) Reaction 3

D) Fructose-6-phosphate

How many steps are found in the CAC?

8

How much ATP is produced per NADH molecule after oxidative phosphorylation? Per FADH2?

NADH- 2.5 per molecule. FADH2 - 1.5 per molecule

How many CO2 are lost per each turn of the CAC?

2 molecules of CO2 are lost.

How many of the steps in the CAC are equilibrium reactions?

5

What reaction is catalyzed by the PDH?

pyruvate to acetyl-CoA

Given the diagram of the citric acid cycle, answer the following questions.

A. (1 pt) What compound is the five-carbon molecule? (contains 5 carbons)

B. (2pt) Identify the four-carbon compounds.

C. (1 pt) How many GTP molecules are produced per turn of this cycle?

D. (1 pt) What is one reaction that is an equilibrium reaction? (give reaction number)

A. a-ketoglutarate

B. Succinate, fumarate, malate, and oxaloacetate

C. 1 GTP

D. Any one of 2, 5, 6, 7, and 8

The B-oxidation pathway is the degradation pathway for fatty acids.

A. Where, in the cell, does the B-oxidation pathway occur?

B. How many steps are in the B-oxidation pathway?

A. In the mitochondria.

B. Four reaction steps.

How many FADH2 and NADH molecules are produced per round of B-oxidation?

One of each FADH2 and NADH.

Which number on the molecule below indicates the A and B carbons?

Carbon 2 is the alpha, and Carbon 3 is the beta.

Can B-oxidation occur with odd-numbered fatty acids? Can B-oxidation occur with fatty chains containing double bonds? Explain your answer in at least three complete sentences.

Yes to both types of chains. The B-oxidation process occurs with both unsaturated fatty acids (those with double bonds) and fatty acids that have an odd number of carbons. Double bonds and odd-numbered chains each present a structural problem for the standard enzymes of the pathway. So, there are additional steps with enzymes for each type of molecule, but the molecules are degraded with energy recovered.

True or False: The ΔG value for a particular reaction is +52kJ/mol. This value indicates the reaction is spontaneous.

False

True or false: A biochemical metabolic pathway is a series of enzyme-catalyzed reactions that convert starting material into products.

Correct!

True

True or false: Three ATP molecules are used in the energy-investing stage of glycolysis.

False

True or False: The citric acid cycle occurs in the presence of oxygen.

True

True or false: The B-oxidation pathway degrades both even-numbered and odd-numbered fatty acids.

Correct!

True

In total, how many net ATP and NADH are produced (or required) in the glucose to pyruvate steps in glycolysis?

1 NADH required

1 ATP and 2 NADH required

2 ATP and 2 NADH produced

2 ATP produced

2 ATP and 2 NADH produced

In converting glucose to pyruvate, how many ATP or NADH are produced (or required) in the phosphoenolpyruvate to pyruvate step in glycolysis?

1 ATP required

1 ATP produced

2 ATP produced

2 ATP required

2 ATP produced

What is the primary product of glycolysis?

Glucose

Glucose-6-phosphate

phosphoenolpyruvate

GAP and DHAP

Pyruvate

Pyruvate

In glycolysis, when glucose enters a cell, it is immediately phosphorylated to form glucose-6-phosphate. The phosphate donor in this reaction is ATP, and the enzyme is ________.

Hexokinase

Aldolase

CoA

Phosphohexose isomerase

None of the above

Hexokinase

In the sixth reaction of glycolysis, ATP is formed by the direct transfer of a phosphate group from a metabolite to ADP. This process is referred to as:

Lipid phosphorylation

Isomerization

Protein phosphorylation

Substrate-level phosphorylation

Photo-protein dephosphorylation

Substrate-level phosphorylation

Under anaerobic conditions, to which compound is pyruvate converted?

NADH

Lactate

Hexokinase

GAP

None of the above

Lactate

How many steps are in the glycolysis pathway?

3

6

10

12

14

10

The reactions of glycolysis take place in/on the ___________.

Mitochondria

Cytosol

Lysozyme

Ribosome

Nucleus

Cytosol

How is ATP used in the initial steps of glycolysis?

Lipid phosphorylation reagent

Isomerization reaction

Source for phosphorylation

Protein production

None of the above

Source for phosphorylation

Which of the following is a ten-step pathway?

A. CAC

B. PDH

C. Glycolysis

D. Oxidative phosphorylation

E. B-oxidation

Glycolysis

How many ATP molecules does NADH yield after oxidative phosphorylation?

1.5

2

2.5

3

3.5

2.5

Besides NADH and FADH2, what energy molecule is produced directly in the citric acid cycle?

ATP

GTP

CTP

TTP

None of the above

GTP

What molecule is missing in the following reaction?

Succinate

The enzymes and coenzymes of the citric acid cycle are all present in the ________.

Mitochondria

Vacuoles

Nucleus

Lysosomes

None of the above

Mitochondria

Cellular respiration is the process of cells taking in ______ and producing ______ to generate energy.

A. Glucose; NADH

B. FAD; FADH2

C. CO2; ATP

D. NAD+; NADH

E. O2; CO2

O2; CO2

The complete degradation of glucose via cellular respiration occurs in ______ phases.

1

2

3

alternate

reversible

3

What are the names of the three enzymes that convert pyruvate to acetyl-CoA

A. P, D, and H

B. Enzyme A, Enzyme B, and Enzyme C

C. Enzyme a, Enzyme b, and Enzyme c

D. E1, E2, and E3

E. None of the above

E1, E2, and E3

Of the following, which coenzyme(s) is (are) necessary for B-oxidation?

A. O2

B. FAD

C. GTP

D. Both A and B

E. None of the above

FAD

Which of the following letters corresponds to the B-carbon of a fatty acid?

(2 carbons from functional group)

The process for degrading fatty acids is commonly referred to as:

A. B-degradation

B. B-degradation

C. Spiral

D. B -spiral

E. A-spiral

B -spiral

(Short answer) Towards the end of the Preparatory Phase of glycolysis, glucose has been converted to two different products.

A) What are the two products?

B) What happens to each product?

In step 4 of glycolysis, glucose (six-carbon) is converted to GAP and DHAP (both 3-carbons). GAP goes on in the glycolysis pathway. The other, DHAP, cannot go on through glycolysis directly; it is converted to GAP by triose phosphate isomerase.

(Fill in the blank) Use the following word bank to fill in the appropriate blanks. Not all words will be used; words can be used more than once.

Word bank: one, two, three, four, five, six,

Glucose contains ___(A)_____ carbon atoms. The preparatory phase of glycolysis consists of ____(B)_____ steps. The oxidation of a glucose molecule utilizes two ATP molecules. Later, the two __(C)____-carbon products of glycolysis produce ____(D)______ ATP by direct phosphorylation, which gives a net yield of two ATP. In addition, ____(E)_____ NADH are produced in glycolysis.

A) six

B) five

C) three

D) four

E) two

(Short response) Consider the fatty acid which has 10 carbons (below).

A. (2 pts) How many cycles of B-oxidation are required for catabolism? Briefly explain.

B. (2 pts) How many acetyl-CoA are produced during catabolism? Briefly explain.

C. (1 pts) How many NADH and FADH2 are produced from B-oxidation (only) of this molecule?

A. 4 cycles are required for oleic acid. Each cycle removes two carbon units. ON the final cycle, two acetyl groups are produced.

B. There are 5 acetyl-CoA groups produced. Two acetyl-CoA groups on the last cycle.

C. There are 4 NADH and 4 FADH2 molecules produced. One per cycle.

Short Essay

Explain the important pathways and energy molecules for the complete oxidative catabolism of glucose to form CO2 and H2O.

(Answer in at least 6 sentences giving specific details, such as molecules and names of pathways.)

First phase: Glucose metabolism begins with glycolysis which degrades the molecule into two molecules of pyruvate and also produces 2 ATP and 2 NADH molecules. The pyruvate is converted to acetyl-CoA. Second Phase: the acetyl-CoA groups are shuttled through the citric acid cycle to generate GTP, NADH, FADH2 molecules along with the release of CO2. Third Phase: the NADH and FADH2 coenzymes are themselves oxidized in the mitochondria to yield ATP by a process called oxidative phosphorylation.