Shared Flashcard Set

Details

Glycolysis & Gluconeogenesis
Exam 2
41
Biochemistry
Undergraduate 3
02/29/2016

Additional Biochemistry Flashcards

 


 

Cards

Term
2 conditions under which metabolism of glucose can occur
Definition
1. anaerobic
2. aerobic
Term
How is metabolism of glucose different in the liver than in the muscles/brain?
Definition
liver = storage

muscles/brain = form ATP
Term
What happens when there are high glucose levels?
Definition
glucose entry into liver & pancreas
Term
glycolysis
Definition
energy by catabolism of glucose
Term
Does glycolysis occur under aerobic or anaerobic conditions?
Definition
anaerobic
Term
stage 1 of glycolysis
Definition
"preparatory phase"; energy invested to form activated sugars
Term
stage 2 of glycolysis
Definition
"payoff phase"
Term
Is the reaction catalyzed by phosphohexose isomerase in glycolysis thermodynamically favorable or unfavorable?
Definition
unfavorable
Term
What is the major regulatory step of glycolysis?
Definition
phosphofructokinase (PFK) catalyzing the 2nd phosphorylation step --> fructose 1,6-bisphosphate
Term
What is the only product formed by aldolase that can continue on in glycolysis?
Definition
glyceraldehyde 3-phosphate
Term
What is the end of the prep phase of glycolysis?
Definition
formation of 2 glyceraldehyde 3-phosphate molecules
Term
What type of catalysis is used by glyceraldehyde 3-phosphate dehydrogenase to convert GAP to 1,3-bisphosphoglycerate in glycolysis?
Definition
covalent catalysis
Term
What mechanism does phosphoglycerate kinase (PGK) use to make ATP in glycolysis?
Definition
substrate level phosphorylation
Term
Does phosphoglycerate mutase create a molecule with a higher or lower energy potential in glycolysis?
Definition
higher
Term
What type of reaction does enolase perform to make 2-PG --> PEP in glycolysis?
Definition
dehydration
Term
What type of reaction is catalyzed by pyruvate kinase (PK) in glycolysis?
Definition
the second substrate level phosphorylation
Term
net reaction of glycolysis
Definition
1 glucose + 2 ADP + 2 Pi + 2 NAD+ --> 2 pyruvate + 2 ATP + 2 NADH + 2 H+ + 2 H2O
Term
Cells oxidize pyruvate to generate ______.
Definition
NAD+
Term
Under anaerobic conditions, animal tissues undergo ______ to regenerate NAD+.
Definition
fermentation of pyruvate --> lactate
Term
What must happen to dietary sugars in order for them to by metabolized?
Definition
they must be converted to glucose or glycolysis intermediates
Term
What is the role of glycolysis in muscle?
Definition
to meet need for ATP
Term
How many steps are there at which glycolysis is regulated in muscle?
Definition
3
Term
How does hexokinase regulate glycolysis in muscle?
Definition
allosterically inhibited by glucose 6-phosphate
Term
What is the most important control site for glycolysis in muscle?
Definition
PFK
Term
When does PFK activity for glycolysis in muscle increase?
Definition
when ATP/AMP ratio decreases
Term
How does pyruvate kinase regulate glycolysis in muscle?
Definition
allosterically inhibited by ATP
Term
What is the point of glycolysis regulation in the liver?
Definition
the liver works to maintain blood glucose levels
Term
What is the primary enzyme for formation of glucose-6-phosphate in the liver?
Definition
glucokinase
Term
How does liver PFK regulate glycolysis?
Definition
energy charge & citrate (the first product of the citric acid cycle)
Term
How does liver pyruvate kinase regulate glycolysis?
Definition
allosterically but also by covalent modification
Term
gluconeogenesis
Definition
process of making new glucose from lactate, pyruvate, & non-carbohydrate precursors
Term
How do you make gluconeogenesis favorable?
Definition
counter exergonic (irreversible) glycolysis steps
Term
How many steps does it take to convert pyruvate to PEP in gluconeogenesis?
Definition
2
Term
fructose-1,6-bisphosphatase (AKA FBP-ase1) (gluconeogenesis)
Definition
catalyzes conversion of fructose-1,6-bisphosphate --> fructose-6-phosphate
Term
glucose-6-phosphate (gluconeogenesis)
Definition
hydrolyzes glucose 6-phosphate to form glucose & orthophosphate (inorganic phosphate)
Term
net reaction of gluconeogenesis
Definition
2 pyruvate + 4 ATP + 2 GTP + 2 NADH + 4 H2O --> glucose + 4 ADP + 2 GDP + 6 Pi + 2 NAD+ + 2H+
Term
When do glycolysis & gluconeogenesis work together?
Definition
in muscle contraction
Term
What is the final product of glycolysis?
Definition
pyruvate
Term
What catalyzes the conversion of pyruvate --> acetyl-CoA?
Definition
pyruvate dehydrogenase complex
Term
3 enzyme components for PDH complex
Definition
1. E1
2. E2 (a trimer)
3. E3 (a dimer)
Term
6 step reaction sequence for the PDH complex
Definition
1. pyruvate binds covalently to TPP cofactor of E1 & becomes decarboxylated
2. E1 transfers hydroxyethyl group from E1 to lipoamide cofactor
3. lipoamide arm with thioacetate swings into active site of E2
4. E2 transfers acetyl group from lipoamide --> coenzyme A
5. E3 oxidizes lipoamide of E2
6. E3 oxidizes FADH2
Supporting users have an ad free experience!