Gluconeogenesis Pathway Quiz and Flashcards

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Questions and Answers

Where does Gluconeogenesis primarily occur?

In the pancreas and spleen.

In the muscles and bones.

In the brain and heart.

In the liver and kidney. (correct)

What is the main purpose of Gluconeogenesis?

To produce ATP for cellular energy.

To convert glucose into glycogen for storage.

To synthesize glucose from non-carbohydrate precursors. (correct)

To break down glucose into non-carbohydrate precursors.

When is Gluconeogenesis particularly important?

During times of sleep.

During times of exercise.

During times of feasting.

During times of fasting. (correct)

What is the coenzyme involved in Reaction 1a of Gluconeogenesis?

Biotin. Signup and view all the answers

Which enzyme is responsible for Reaction 1b of Gluconeogenesis?

Phosphoenolpyruvate carboxykinase. Signup and view all the answers

Which glycolytic intermediate continues through the reversible reactions of glycolysis in Gluconeogenesis?

Phosphoenolpyruvate. Signup and view all the answers

What is the enzyme responsible for Reaction 9 of Gluconeogenesis?

Fructose 1,6-bisphosphatase. Signup and view all the answers

What is the enzyme responsible for Reaction 10 of Gluconeogenesis?

Phosphoglucose isomerase. Signup and view all the answers

What is the purpose of Bypass reaction 3 in Gluconeogenesis?

To convert glucose-6-phosphate into glucose. Signup and view all the answers

Which of the following is a product of anaerobic glycolysis?

Lactate Signup and view all the answers

What happens to lactate in the liver?

It is converted to glucose Signup and view all the answers

Which amino acids are considered glucogenic?

Alanine and glutamine Signup and view all the answers

What enzyme is involved in the conversion of alanine to pyruvate?

Alanine Transaminase (ALT) Signup and view all the answers

What is the coenzyme required for the transamination reaction?

Pyridoxal phosphate (PLP) Signup and view all the answers

Which shuttle system is used when the starting substrate is alanine?

Malate shuttle Signup and view all the answers

What happens to oxaloacetate in the malate shuttle?

It is converted to phosphoenolpyruvate (PEP) Signup and view all the answers

What happens to lactate in the cytosol in the lactate shuttle?

It is converted to pyruvate Signup and view all the answers

Where does gluconeogenesis begin in the cell?

Mitochondria Signup and view all the answers

Why can't oxaloacetate cross the inner mitochondrial membrane?

It is charged Signup and view all the answers

Which enzymes converts Lactate to Pyruvate?

LDH in liver cytosol Signup and view all the answers

The cori cycle outlines the production and recycling of...

Lactate Signup and view all the answers

The cori cycle can occur in a red blood cell

True Signup and view all the answers

Glycerol can enter the gluconeogenesis pathway by being converted to...

Signup and view all the answers

ALT uses PLP as a coenzyme, which is derived from..

Vitamin B6 Signup and view all the answers

Oxaloacetate is converted to Malate by...

Signup and view all the answers

Pyruvate is converted to oxaloacetate by...

Pyruvate Carboxylase Signup and view all the answers

PEP Carboxykinase converts...

Oxaloacetate to PEP Signup and view all the answers

Study Notes

Gluconeogenesis Overview

Primarily occurs in the liver and kidneys.
Main purpose is to synthesize glucose from non-carbohydrate precursors during periods of fasting or low carbohydrate intake.
Particularly important during prolonged fasting, intense exercise, or when carbohydrate intake is insufficient.

Key Enzymatic Reactions

Coenzyme involved in Reaction 1a is Biotin.
Reaction 1b is catalyzed by Pyruvate carboxylase.
Glycolytic intermediate that continues through reversible reactions is Dihydroxyacetone phosphate (DHAP).
Reaction 9 is catalyzed by Fructose-1,6-bisphosphatase.
Reaction 10 is catalyzed by Glucose-6-phosphatase.

Bypass Reactions

Bypass reaction 3 serves to circumvent the irreversible phosphofructokinase step of glycolysis, allowing gluconeogenesis to proceed efficiently.

Lactate and the Cori Cycle

A product of anaerobic glycolysis is lactate.
In the liver, lactate is converted back into glucose through gluconeogenesis.
The Cori cycle outlines the production and recycling of glucose and lactate between muscle and liver.
The Cori cycle can occur in red blood cells, where lactate is produced and shipped to the liver.

Glucogenic Amino Acids

Glucogenic amino acids can be converted into glucose precursors; examples include alanine, glutamine, and serine.
Alanine is converted to pyruvate via transamination using the enzyme alanine transaminase (ALT).
Coenzyme required for the transamination reaction is pyridoxal phosphate (PLP).

Shuttle Systems

The alanine shuttle system utilizes the conversion of alanine to pyruvate and vice versa for transport of nitrogen.
In the malate shuttle, oxaloacetate is converted to malate to facilitate its transport across the inner mitochondrial membrane, as oxaloacetate cannot cross it directly.
In the lactate shuttle, lactate in the cytosol can also be converted back to pyruvate when needed.

Additional Conversion Reactions

Lactate is converted to pyruvate by the enzyme lactate dehydrogenase.
Glycerol can enter the gluconeogenesis pathway by being converted to dihydroxyacetone phosphate (DHAP).
Elevated levels of pyruvate activate pyruvate carboxylase, converting pyruvate to oxaloacetate, while phosphoenolpyruvate carboxykinase (PEPCK) converts oxaloacetate to phosphoenolpyruvate (PEP).
Oxaloacetate is converted to malate by malate dehydrogenase.

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Description

Test your knowledge on gluconeogenesis with this quiz! Learn about the synthesis of glucose from non-carbohydrate precursors and understand how it differs from glycolysis. Challenge your understanding of this important metabolic pathway and determine if gluconeogenesis is simply a reversal of glycolysis.

Gluconeogenesis Quiz

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