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BioChemistry Keywords Ch31
BioChemistry DPPP-368 Keywords Chapter 31
61
Biochemistry
Undergraduate 3
03/30/2011
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Term
Acetyl CoA:
 Definition
During gluconeogenesis, fatty acids are converted into acetyl CoA, which in turn is converted to ketone bodies that can be used by the muscles and brain for energy
Term
Adenyl cyclase:
 Definition
In the fasting state, glucagons binds to surface cell receptors , activates adenylate cyclase, causing cAmp levels in liver cells to rise
Term
Alanine aminotransferase:
 Definition
enzyme that converts alanine to pyruvate
Term
Amino acids:
 Definition
one of the 3 major carbon sources for gluconeogenesis. The major gluconeogenic amino acid is alanine.
Term
ATP:
 Definition
Energy source for gluconeogenesis
Term
Biotin:
 Definition
Cofactor that is used during the conversion of pyruvate to oxaloacetate
Term
cAMP:
 Definition
After the activation of Adenylate cylase, cAMP levels rise, activating protein kinase A. Glycogen synthesis decreases.
Term
Catalytic subunits:
 Definition
a feature of protein kinase A. In gluconeogenesis, cAmp binds to the regulatory subunits of protein kinase A.
Term
Cortisol:
 Definition
A stress hormone that promotes the release of glycerol from adipose tissue. Elevated Cortisol levels also promote the release of amino acids from muscle.
Term
Covalent modification:
 Definition
In gluconeogenesis, the control enzymes PFK-2 and FBPase-2 are regulated by covalent modification in the form of phosphorylation. PFK-2 is inhibited. FBPase-2 is activated.
Term
Energy:
 Definition
Glucose synthesis requires energy. Under fasting conditions, the energy required for gluconeogenesis is obtained from the ? oxidation of fatty acids.
Term
Epinephrine:
 Definition
A stress hormone that promotes the release of glycerol from adipose tissue.
Term
Exercise:
 Definition
During exercise, muscles produce lactate, which can enter the cycle for gluconeogenesis. While exercising, the liver maintains blood glucose through glucagons and epinephrine. Induces glycogenolyis and gluconeogenesis.
Term
Fasting:
 Definition
During a fast, the body relies on gluconeogenesis to supply glucose to tissues.
Term
Fatty acids:
 Definition
The oxidation of fatty acids provides acetyl CoA. Fatty acids are oxidized to acetyl CoA in the liver to provide energy for gluconeogenesis.
Term
Feed forward activation:
 Definition
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Term
Fructose 6-phosphate:
 Definition
An intermediate in the conversion of PEP to glucose. In gluconeogenesis, it is activated by Between glucose 6-phosphate and fructose 1,6-biphosphate
Term
Fructose 1,6-biphosphate:
 Definition
An intermediate in the conversion of PEP to glucose. Precursor of glucose 6-phosphate
Term
Fructose 1,6–biphosphotase:
 Definition
Enzyme that converts Fructose 1,6-biphosphate to fructose 6-phosphate.
Term
Fructose 2,6-biphosphate:
 Definition
In gluconeogenesis, F2,6BP is an allosteric inhibitor of fructose 6-phosphate. Inhibits the enzyme F1,6Pase
Term
G Protein:
 Definition
Protein that transmits signal from glucagons cell receptor to adenylate cyclase, triggering cAMP
Term
Glucagon:
 Definition
Secreted by the ? cells of the pancreas. Causes glycogen synthesis to decrease.
Term
Glucagon receptor:
 Definition
Cell surface receptor that binds glucagon.
Term
Gluconeogenesis:
 Definition
Process by which glucose is synthesized from non-carbohydrate precursors. Occurs primarily in the liver under fasting conditions.
Term
Glucose:
 Definition
The primary fuel source for most tissues of the body. The end product of gluconeogenesis.
Term
Glucose-6-phosphotase:
 Definition
Enzyme that converts glucose 6-phosphate to glucose
Term
Glucose 1-P:
 Definition
Produced during the degradation of glycogen by phosphorylase a. Converted to glucose 6-phosphate.
Term
Glycerol:
 Definition
A potential source of carbon for gluconeogenesis. Formed from the breakdown of adipose triacylglycerols.
Term
Glycerol kinase:
 Definition
Converts glycerol to glycerol-3 phosphate dehydrogenase.
Term
Glycerol-3 phosphate dehydrogenase:
 Definition
Enzyme that converts DHAP to glycerol 3-phosphate.
Term
GTP:
 Definition
Provides energy for the conversion of oxaloacetate to phosphoenolpyruvate. Also provides the phosphate group for PEP.
Term
High protein diet:
 Definition
Stimulates gluconeogenesis. Amino acids are available for gluconeogenesis when the dietary intake of protein is high and the intake of carbohydrates is low.
Term
Induction:
 Definition
Increase of gene transcription / mRNA translation. Inducible enzymes in gluconeogenesis include PEPCK and glucose-6-phosphatase.
Term
Insulin:
 Definition
Hormone secreted by the ? cells of the pancreas in response to elevated blood glucose. Insulin promotes the storage of glucose as glycogen (by countering the effects of glucagons-stimulated phosphorylation). It also promotes the synthesis of TAG released from liver into blood as VLDL.
Term
Insulin resistance:
 Definition
Insulin resistance is a condition in which the body produces insulin but does not use it properly. Insulin becomes less effective at lowering blood sugars. The resulting increase in blood glucose may raise levels outside the normal range and cause adverse health effects.
Term
Impaired glucose tolerance:
 Definition
(IGT) is the name given to define blood glucose levels that are higher than normal, but below the level of a person with diabetes. IGT is a combination of impaired secretion of insulin and reduced insulin sensitivity (insulin resistance). IGT may precede type 2 diabetes mellitus by many years
Term
Ketone bodies:
 Definition
In a prolonged fast, Acetyl CoA is converted to ketone bodies, which enter the blood and serve as an additional fuel source for the muscle and brain.
Term
Lactate:
 Definition
Precursor for gluconeogenesis. Produced by anaerobic glycolysis.
Term
Lactate dehydrogenase:
 Definition
Oxidizes lactate to pyruvate
Term
Lipolysis:
 Definition
During prolonged fasting, hormonal changes stimulate the breakdown of adipose triacylglycerols. Fatty acids and glycerol are released into the blood. Glycerol is a carbon source for gluconeogenesis.
Term
Malate:
 Definition
Intermediate of gluconeogenesis. Transported out of the mitochondria via the malate/aspartate shuttle.
Term
Malate dehydrogenase:
 Definition
Enzyme responsible for the interconversion of malate to oxaloacetate.
Term
Mitochondria:
 Definition
In gluconeogenesis, the conversion of pyruvate to oxaloacetate occurs in the mitochondria. OAA is converted to either malate or aspartate to facilitate transport to the cytosol.
Term
Muscle degradation:
 Definition
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Term
NADH:
 Definition
In gluconeogenesis, the coenzyme is required for the conversion of oxaloacetate to malate, lactate to pyruvate, and glycerol to dihydroxyacetone phosphate.
Term
Oxaloacetate:
 Definition
Intermediate in the production of phosphoenolpyruvate (PEP) within mitochondria, OAA is converted to malate / PEP are converted back to OAA – converted to PEP.
Term
Phosphoenolpyruvate (PEP):
 Definition
formed from pyruvate via a multi-step synthesis
Term
Phosphoenolpyruvate carboxylkinase (PEPCK):
 Definition
Enzyme that converts PEP from OAA located in the cytosol / mitochondria. Distributed equally in each compartment.
Term
Phosphofructokinase-1:
 Definition
In gluconeogenesis, PFK-1 is inhibited by citrate and ATP, which decreases glycolysis.
Term
Phosphofructokinase-2/Fructose 2,6-biphosphatase:
 Definition
This enzyme is activated by protein kinase A, consequently lowering fructose 2,6-biphosphate levels, which ultimately inhibits glycolysis.
Term
Phosphorylase:
 Definition
phosphorylase a degrades glycogen producing glucose 1-phosphate, which is eventually converted to glucose.
Term
Phosphorylase kinase:
 Definition
A regulatory enzyme of gluconeogenesis. When activated by protein kinase A, phosphorylase kinase converts phosphorylase b to phosphorylase a.
Term
Protein:
 Definition
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Term
Protein kinase A:
 Definition
Phosphorylates and activates phosphorylase kinase / inactivates glycogen synthase.
Term
Pyruvate:
 Definition
An intermediate of gluconeogenesis. Pyruvate is produced in the liver from lactate or alanine. Other amino acids may also be converted to pyruvate.
Term
Pyruvate carboxylase:
 Definition
Enzyme that converts pyruvate to OAA. Found in the mitochondria.
Term
Pyruvate dehydrogenase:
 Definition
Enzyme that converts pyruvate to Acetyl CoA. During gluconeogenesis, pyruvate dehydrogenase is inactivated.
Term
Pyruvate kinase:
 Definition
Enzyme that converts PEP to pyruvate
Term
Regulatory subunits:
 Definition
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Term
Starvation:
 Definition
Prolonged fasting, resulting in elevated levels of circulating ketone bodies, reduced utilization of glucose by the brain and nervous system, and decreased rate of gluconeogenesis in the liver.
Term
Stress:
 Definition
q
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