Gluconeogenesis Flashcards
Gluconeogenesis is the formation of glucose from _____ (_____) or _______ (______)
Pyruvate, glycolysis, oxaloacetate, TCA cycle
Glycolysis enzymes which catalyze _____ _____ are used
Reversible reactions
Pyruvate is converted to PEP in _____ steps
Two
PEP stands for
Phosphoenolpyruvate
The intermediate between pyruvate and PEP is _____
Oxaloacetate
Carbon dioxide is _____ in the first step to pyruvate and ______ from ______ in the second step
added,released, oxaloacetate
The conversion from pyruvate to PEP is an _________ reaction and is coupled with the hydrolysis of both ____ and _____
endergonic, GTP, ATP
The pyruvate carboxylase mechanism requires a _____
biotin cofactor
Many _____ transfer reactions proceed through a similar mechanism and require ______
CO2, biotin
The enzyme that converts pyruvate to oxaloacetate is _____
Pyruvate carboxylase
The enyme that converts oxaloacetate to PEP is____
PEP carboxykinase
The enzyme that converts fructose 1,6-bisphosphate to fructose 6-phosphate is ____
Fructose 1,6-bisphosphatase
_____ converts glucose 6-phosphate to glucose
Glucose 6-phosphatase
The final two unique enzymes of gluconeogenesis are _____
phosphatases
The reaction equation for glycolysis is?
Glucose + 2 ADP + 2pi —> 2 pyruvate + 2 ATP
the reaction equation for gluconeogenesis is?
2 pyruvate + 6 ATP –> glucose + 6 ADP + 6 Pi
If glycolysis and gluconeogenesis occured simultaneously, there would be ____
A net consumption of ATP
What is the role of pyruvate kinase?
It catalyzes the conversion of PEP to Pyruvate
Pyruvate kinase activity is regulated ______ by __________ and _____
allosterically, feed-forward activation, product inhibition
Feed-forward activation of pyruvate kinase by: ________
Fructose 1,6-bisphosphate
Product inhibition regulation of pyruvate kinase by: _____
ATP
List 3 ways pyruvate kinase is regulated:
Product inhibition–ATP, Feed-forward activation–Fructose -1,6-bisphosphate, phosphorylation by protein kinase A (PKA)
What are the four possible ways pyruvate can be converted into?
- Acetyl CoA, 2. Oxaloacetate. 3. Lactate, 4. Ethanol + CO2
What happens after pyruvate is converted to acetyl-CoA?
Acetyl-CoA can enter the TCA cycle or be converted into fatty acids
What happens after pyruvate is converted to oxaloacetate?
Oxaloacetate is a substrate for the TCA cycle, gluconeogenesis, and an intermediate in amino acid biosynthesis
What happens after pyruvate is converted to lactate?
It is part of the anaerobic pathway in the muscles to regenerate NAD+
What happens after pyruvate is converted to ethanol + CO2?
Anaerobic pathway to regenerate NAD+ through fermentation
Pyruvate can be ___ to Acetyl-CoA
Oxidized
What enzyme causes the decarboxylation of Pyruvate into Acetyl-CoA?
Pyruvate dehydrogenase
What does pyruvate dehydrogenase do?
Converts 3-carbon pyruvate into 2-carbon acetyl-CoA
What kind of bonds does Acetyl-CoA have?
High-energy thioester bond
____ converts pyruvate to oxaloacetate
Pyruvate carboxylase
How is pyruvate converted into ethanol?
It is converted to acetaldehyde by pyruvate decarboxylase, acetaldehyde is converted to ethanol by alcohol dehydrogenase
Why must NAD+ be regenerated?
Muscle contractions occur anaerobically so NAD+ must be regenerated to allow glycolysis to continue
What happens to the generated lactate?
It is transported to the liver where it can be converted back to pyruvate
Muscle tissue converts ____ to _____
Pyruvate, lactate
What is the enzyme that converts pyruvate to lactate?
Lactate dehydrogenase
During the Cori cycle, ____ generated in the ___ during _______ is transported to the ___ via the _____
Lactate, muscle tissue, anaerobic exercise, liver, blood
What happens to lactate in the liver?
It is converted into glucose by gluconeogenesis which can then be transported back to the muscle for additional energy
Ethanol is processed in the ____ to _____
liver, acetate
Humans do not convert ____ to ethanol, but do metabolize ingested ethanol into _____ through a ____ process that generates _____
pyruvate,acetate,two-step, two molecules of NADH
The enzyme alcohol dehydrogenase converts the reversible reaction of _____ to ____ using or generating _____
Acetaldehyde, ethanol, NADH or NAD+
______ converts acetaldehyde to acetate
Aceltaldehyde dehydrogenase
