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Pathway of Atoms in Fermentation

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A "Pulse-chase" experiment using 14C-labeled carbon sources is carried out on a yeast extract maintained under strictly anaerobic conditions to produce ethanol. The experiment consists of incubating a small amount of 14C-labeled substrate (the pulse) with the yeast extract just long enough for each intermediate in the fermentation pathway to become labeled. The label is then "chased" through the pathway by the addition of excess unlabeled glucose. The chase effectively prevents any further entry of labeled glucose into the pathway.
(a) If [1-14C]glucose (glucose labeled at C-1 with 14C) is used as a substrate, what is the location of 14C in the product of ethanol? Explain.
(b) Where would 14C have to be located in the starting glucose to ensure that all the 14C activity is liberated as 14CO2 during fermentation to ethanol? Explain.

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a) Overall reaction is -

Glucose + 2 ADP + 2 Pi --> 2 Ethanol + 2 CO2 + 2 ATP + 2 H2O

Many microorganisms and yeast ferment glucose to ethanol and CO2. In this two step reaction 1. Glycolysis - glucose is converted to ...

Solution Summary

Solution is 170 words in response text. As well, it includes an attached drawing of compound structures with explanations.

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Mutiple choice

MULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the question.

1) In absence of oxygen, a yeast cell undergoes fermentation and uses 100 molecules of glucose. How much net ATP will be generated?
A) 100 B) 36 C) 400 D) 300 E) 200

2) All the following statements pertaining to catalysts are true EXCEPT
A) catalysts are not permanently altered during reaction.
B) catalysts increase reaction rate.
C) catalysts increase activation energy requirements.
D) biological catalysts are specific enzymes.
E) catalysts can be used over and over again.

MULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the question.

6) Both plants and animals perform
A) glycolysis.
B) fermentation.
C) Krebs cycle.
D) photosynthesis.
E) A, B and C are correct.

7) The insecticide rotenone inhibits one of the steps of the electron transport system in mitochondria. What is the immediate result?
A) Electron transport will increase.
B) Transport of pyruvate into the mitochondria will increase.
C) The cells will utilize oxygen more rapidly.
D) The rate of the Krebs cycle reactions will increase.
E) The rate of fermentation will increase.

8) Which of the following has potential energy?
A) a diver on a springboard
B) a water droplet on top of a waterfall
C) a glucose molecule
D) a 9V battery
E) all of the above

MULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the question.

11) The products of glycolysis are
A) ATP, NADH, pyruvate, FADH2.
B) ATP, NADH, pyruvate.
C) ATP, NADH, FADH2, CO2.
D) ATP, NADH, Acetyl CoA.
E) ATP and pyruvate.

12) During which part of aerobic respiration is the oxygen actually used?
A) fermentation
B) conversion of pyruvate to Acetyl CoA
C) glycolysis
D) electron transport system
E) Krebs cycle

MULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the question.

14) When a muscle cell demands energy to perform its work of contraction, what happens to ATP?
A) ATP is broken down.
B) ATP receives an extra phosphate.
C) ATP enters a metabolic pathway.
D) ATP manufactures more ATP.
E) ATP catalyzes the reaction.

15) Each of the following contains twelve carbon atoms. Which of the arrangements demonstrates carbon atoms with the greatest entropy?
A) four molecules of C3H4O3
B) twelve molecules of CO2
C) one molecule of C12H22O11
D) two molecules of C6H12O6
E) It is impossible to determine.

16) Which of the following colors of light will be most effective for growth of green plants?
A) orange and yellow
B) red and blue
C) red and green
D) blue
E) green

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