300896 Lecture Notes - Lecture 14: Citric Acid Cycle, Acetyl-Coa, Acetyl Group

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amberhippopotamus661

23 Apr 2019

School

UWS

Department

University of Western Sydney

Course

300896

Professor

anon

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Document Summary

Two carbon atoms come into the citric acid cycle from each acetyl group, representing four out of the six carbons of one glucose molecule. Two carbon dioxide molecules are released on each turn of the cycle; however, these do not necessarily contain the most recently-added carbon atoms. The two acetyl carbon atoms will eventually be released on later turns of the cycle; thus, all six carbon atoms from the original glucose molecule are eventually incorporated into carbon dioxide. Each turn of the cycle forms three nadh molecules and one. These carriers will connect with the last portion of aerobic respiration to produce atp molecules. Gtp or atp is also made in each cycle. Several of the intermediate compounds in the citric acid cycle can be used in synthesizing non-essential amino acids; therefore, the cycle is amphibolic (both catabolic and anabolic). After glycolysis, pyruvate is converted into acetyl coa in order to enter the citric acid cycle.

Related Questions

Select all of the following statements that are true concerning the citric acid cycle:

______________________

__	NAD+ an FAD become reduced.

__	High-energy carbon dioxide molecules will be generated by substrate-level phosphorylation.

__	ATP is synthesized by chemiosmosis.

__	The organic carbon (from acetyl CoA) that enters the cycle will be completely oxidized in the mitochondrial matrix.

__	Citrate must be continuously regenerated to prepare the cycle to process incoming acetyl CoA.

__	Upon entry into the citric acid cycle, acetyl CoA is combined with oxaloacetate.

__	Two ATP molecules will be consumed for each acetyl CoA that is processed by the cycle.

__	Organic molecules are oxidized in several different steps of the cycle.

1. Integrated metabolism

A. A molecule of glucose that you eat can eventually be transformed into part of a fatty acid that you store. Circle the pathways/cycles below that are part of this overall flow of carbon atoms. Cross out any that are not.

Gluconeogenesis, beta-oxidation, citric acid cycle, glycolysis, urea cycle, fatty acid synthesis

B. Trace the metabolic path of this glucose molecule through the enzymes it encounters along the way to being made into fat. Write all the enzymes in the list below into the proper places in the figure below. If the enzyme is not used, write its name in a ânot used" column. If it is used, write the enzyme in the order that the carbon atoms from glucose encounter the enzymes.

Pyruvate dehydrogenase, fumarase, aldolase, lactate dehydrogenase, pyruvate kinase, acetyl CoA carboxylase, fatty acid synthase, hexokinase, carnitine acyltransferase, ATP synthase

B. What is the minimum number of glucose molecules that would be necessary to be the carbon source for synthesis of a 16-carbon fatty acid through this pathway?

C. How many net glucose can be made from one molecule of a 16-carbon fatty acid?

2. Describe each cycle/transport system (compounds, compartments, tissues) and explain its purpose:

A. citrate transport system

B. Cori cycle

C. glucose/alanine cycle

Explain the logic of these pathway regulations:

A. Phosphofructokinase, not hexokinase, is the main regulation site of glycolysis.

B. SuccinylCoA inhibits the entry of acetyl CoA into the citric acid cycle.

C. NADH inhibits pyruvate dehydrogenase.

D. Citrate inhibits the citric acid cycle and activates acetyl-CoA carboxylase.

E. Insulin leads to activation of glycogen synthase.

ochrereindeer904

Which of the following is not a net product of the citric acid cycle for each molecule of pyruvate generated in glycolysis?

Select one:

a. 1 ATP (GTP)

b. 1 acetyl coA

c. 3 NADH

d. 1 FADH2

Question 2

Which of the following is NOT an end product for an acetyl group that enters the citric acid cycle?

Select one:

a. ATP

b. NADH

c. FADH2

d. oxaloacetate

Question 3

Once they have been processed through the citric acid cycle, the acetyl-CoA molecules from a single glucose molecule produce:

Select one:

a. 2 ATP, 6 NADH, 4 CO₂.

b. 6 NADH, 6 GTP.

c. 6 FADH₂, 2 ATP, 6 CO₂.

d. 6 GTP, 6 FADH₂.

e. 4 CO₂, 6 FADH₂, 2 ATP.

Question 4

The products of the citric acid cycle breaking down 2 acetyl-CoA include 2 ATP (converted from GTP), 6 NADH and 2 FADH2.

Select one:

True

False

300896 Lecture Notes - Lecture 14: Citric Acid Cycle, Acetyl-Coa, Acetyl Group

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