Glucose-Alanine Cycle

Question 1

What is the overall role and main aim of the GLucose -Alanine Cycle?

Answer 1

Transport of Nitrogen to the Liver

Question 2

Which other cycle/process is the Glucose-Alanine Cycle identical to apart form one molecule?

Answer 2

The Cori Cycle

Question 3

What molecule acts as a transporter for blood transport of nitrogen in the glucose-alanine cycle?

Answer 3

Alanine

Question 4

What conditions promote the glucose-alanine cycle?

Answer 4

High exercise or Fasting

Question 5

Blood transport of nitrogen to the liver in the glucose-alanine cycle can be transported via alanine and which other molecule?

Answer 5

Glutamine

Question 6

What molecule does alanine combine with in the liver during the glucose -alanine cycle to form pyruvate and glutamate?
What is this process called?

Answer 6

alpha-ketoglutarate

Question 7

What happens to glutamate produced in the liver during the glucose alanine cycle?

Answer 7

Undergoes oxidative deamination to NH4+

Then converted to urea in the urea cycle

Question 8

How does the production of pyruvate in the liver during the glucose-alanine cycle provide the conditions for a “cycle” to take place? i.e. describe the outline of the cycle

Answer 8

Pyruvate can be converted to glucose (gluconeogenesis) which can then act as a blood transporter back to muscles where it can be converted to pyruvate (glycolysis)
Pyruvate converts to alanine, transports in the blood, and back to pyruvate in the liver

Question 9

In what conditions does the Cori cycle occur?

Answer 9

Anaerobic

Question 10

How does the Cori Cycle differ from the glucose-alanine cycle?

Answer 10

Lactate acts as a transporter in the blood from muscles to the liver instead of alanine

Question 11

In what ways are the glucose-alanine and Cori-cycle similar?

Answer 11

Both cycles act in the same direction
Both convert to pyruvate in the liver, then to glucose (gluconeogenesis) for use as a transporter in the blood,
then back to pyruvate in muscles (glycolysis)

Question 12

What combines with pyruvate in muscles during the glucose alanine cycle to form alanine and alpha-ketoglutarate?
what is the name of this process?

Answer 12

Glutamate

Transamination

Question 13

Why is there a necessity for the glucose-alanine cycle particularly during times of fasting or high exercise?

Answer 13

Muscles use branched chain amino acids as a fuel for TCA and OxPhos
Muscles cannot breakdown NH4+ in the Urea cycle because it doesn’t have the enzyme for this
Therefore, must be transported to the liver for breakdown via the Urea Cycle (only place where the urea cycle takes place)