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How many and what are the common enzymes used between glycolysis and gluconeogenesis?
7: Phosphoglucose Isomerase; Aldolase; Triose Phosphate Isomerase; Glyceraldehyde-3-Phosphate Dehydrogenase; Phosphoglycerate Kinase, Phosphoglycerate Mutase; Enolase
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Identify the enzymes that are unique to gluconeogenesis
- Pyruvate carboxylase
- PEP carboxykinase
- Fructose-1,6-bP
- Glucose-6-phosphatase
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What are the txtbook substrates of gluconeogenesis?
- Lactate via the Cori Cycle
- Glycerol via conversion to DHAP
- Alanine via conversion to pyruvate
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Identify the substrates of gluconeogenesis
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Identify the regulation points of gluconeogenesis
- Synthesis of PEP
- Conversion of fructose-1,6-bisphosphate to fructose-6-phosphate
- Formation of glucose from glucose-6-phosphate
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Define gluconeogenesis
The process is generally the reverse of glycolysis with the exception of three key steps
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Define the Pentose Phosphate Pathway
Refers to metabolism of glucose that does not generate ATP but is used to form several important molecules used in other processes
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What can cells in the liver use to make glucose?
lactate, pyruvate, glycerol, and certain a-keto acids
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What other organ besides the liver can make glucose?
Kidneys can make a small amount of glucose
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When is gluconeogensis only used?
When glycogen is depleted from the liver which can be caused by intesnse exercise or prolonged fasting
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What depends on glucose for energy?
Brain and rbc's
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What are the enzyme(s) required for the synthesis of PEP?
- Pyruvate carboxylase
- PEP carboxykinase
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What is the function of Pyruvate carboxylase and where does the rxn take place?
In the mitochondria converts pyruvate to oxaloacetate (OAA) by the addition of CO2
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What is the function of PEP carboxykinase?
Converts OAA to PEP
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Gluconeogenesis is generally the reverse of glycolysis with the exception of three key steps:
Hexokinase, PFK-1, and pyruvate kinase
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Which enzyme requires the coenzyme biotin?
Pyruvate carboxylase
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During gluconeogenesis regulation, what activates and inhibits pyruvate carboxylase?
- Activates: Acetyl-CoA
- Inhibits: Nothing on pic
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During gluconeogenesis regulation, what activates and inhibits Fructose-1,6-bisphosphatase?
- Activates: ATP; citrate
- Inhibits: Fructose-2,6-bisphosphate, AMP
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During glycolysis regulation, what activates and inhibits Hexokinase?
- Activates: Nothing on pic
- Inhibits: Glucose-6-phosphate
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During glycolysis regulation, what activates and inhibits Phosphofructokinase?
- Activates: Fructose-2,6-bP; AMP
- Inhibits: ATP, citrate
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During glycolysis regulation, what activates and inhibits Pyruvate Kinase?
- Activates: Nothing on pic
- Inhibits: ATP; Fructose-1,6-bP; Acetyl-CA; cAMP-dependent phosphorylation
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What are 3 key products of Pentose Phosphate Pathway?
- Ribose-5-phosphate-makes ribonulceotides
- Fructose-6-phosphate
- Glyceraldehyde-3-phosphate
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When does the Pentose Phosphate Pathway generate 2 molecules of NADPH?
Oxidative phase
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What are the two phases of pentose phosphate pathway?
Oxidative and Nonoxidative
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What is produced from the Oxidative Phase of Pentose Phosphate Pathway?
- Glucose-6-phosphate is used and proceeds through three enzyme-catalyzed reactions to form D-ribulose-5-phosphate
- 2NADH
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Where is the oxidative phase active?
adipose tissue, red blood cells, and certain other tissues
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What is the important of NADPH molecules?
Key antioxidants and are needed during lipid synthesis
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What is produced during the nonoxidative phase?
Ribose-5-phosphate
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How is Ribose-5-phosphate formed?
Ribulose-5-phosphate from oxidative phase is converted to ribose-5-phosphate
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What can be made during the nonoxidative phase from Ribulose-5-phosphate (oxidative) when cells don't need pentose phosphates (ribose)?
Cells use the other reactions of this phase to form glycolytic intermediates (F6P, GAP)
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Are the rxns during the oxidative phase reversible or irreversible?
irreversible
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Are the rxns during the nonoxidative phase reversible or irreversible?
reversible
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Where is the pentose phosphate pathway located?
cytoplasm
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