Glycolysis and Gluconeogenesis Flashcards
Glycolysis derived from the Greek
stem glyk- , meaning?
sweet
Glycolysis derived from the Greek word lysis, meaning?
dissolution
There are two types of glycolysis:
aerobic glycolysis and anaerobic
which require oxygen
aerobic glycolysis
which doesn’t require oxygen
anaerobic
is at the hub of carbohydrate metabolism because virtually all sugars can ultimately be converted into glucose.
Glycolysis
Two Phases of Glycolysis:
- Preparatory phase
- Payoff phase
The process of glycolysis involves breaking down six-carbon glucose into two three carbon pyruvate molecules in 10 steps, with the first 5 being the preparatory phase.
Preparatory phase
is used during the preparation phase of glycolysis to increase the free energy content of the intermediates and transform the
carbon chains of all metabolized hexoses into glyceraldehyde 3-phosphate.
ATP
phase of glycolysis is when the energy gain occurs.
Payoff phase
In the first step of glycolysis, glucose is activated for subsequent reactions by its phosphorylation at C-6 to
yield glucose 6-phosphate, with ATP as the phosphoryl donor.
Phosphorylation of Glucose
catalyzes the reversible isomerization of glucose 6-phosphate, an aldose, to fructose 6-phosphate, a ketose.
phosphoglucose isomerase
catalyzes the transfer of a phosphoryl group from ATP to fructose 6-phosphate to yield fructose 1,6-bisphosphate.
phosphofructokinase-1 (PFK-1)
The enzyme fructose 1,6- bisphosphate aldolase, often called simply?
aldolase
catalyzes a reverse aldol
condensation.
aldolase
is cleaved to yield two different triose phosphates
Fructose 1,6-bisphosphate
Fructose 1,6- bisphosphate is cleaved to yield two different triose phosphates, namely:
- glyceraldehyde 3- phosphate
(an aldose) - dihydroxyacetone phosphate
(a ketose)
can be directly degraded in the subsequent steps of glycolysis.
glyceraldehyde 3- phosphate
is immediately and reversibly converted to glyceraldehyde 3-phosphate by the fifth enzyme of the glycolytic sequence, triose
phosphate isomerase.
dihydroxyacetone phosphate
dihydroxyacetone phosphate, is immediately and reversibly converted to glyceraldehyde 3-phosphate by the fifth enzyme of the glycolytic sequence?
triose phosphate isomerase.
First step in the payoff phase is the oxidation of glyceraldehyde 3-phosphate to?
1,3-bisphosphoglycerate
first step in the payoff phase is the oxidation of glyceraldehyde 3-phosphate to 1,3-bisphosphoglycerate, catalyzed by?
glyceraldehyde 3- phosphate dehydrogenase.
The enzyme? transfers the highenergy phosphoryl group from the carboxyl group of 1,3- bisphosphoglycerate to ADP , forming ATP and 3- phosphoglycerate.
phosphoglycerate kinase
The enzyme ? catalyzes a reversible shift of the phosphoryl group between C-2 and C-3 of glycerate; Mg2+ is essential for this reaction.
phosphoglycerate mutase
promotes reversible removal of a molecule of water from 2-phosphoglycerate to yield
phosphoenolpyruvate (PEP).
enolase
The last step in glycolysis is the transfer of the phosphoryl group from phosphoenolpyruvate to ADP , catalyzed by?
pyruvate kinase
is a near-universal pathway by which a glucose molecule is oxidized
Glycolysis
is the process of glucose and glycogen biosynthesis from noncarbohydrate sources.
Gluconeogenesis
The important
precursors of glucose in animals are three-carbon compounds such as?
lactate, pyruvate, and glycerol as well as certain amino acids
A versatile biological molecule that consists of three carbon atoms and two functional groups - a
carboxylate and a ketone group.
Pyruvate
a versatile biological molecule that consists of three carbon atoms and two functional groups
- carboxylate
- ketone group
is a product of anaerobic glycolysis.
Lactate
comes from adipose tissue lipolysis.
Glycerol
serve as substrates for endogenous glucose production (gluconeogenesis) in the liver.
Amino Acids
starts from simple organic compounds of two or three carbons, such as?
acetate, lactate, and propionate
is converted to PEP or phosphoenolpyruvate via oxaloacetate in two steps
catalyzed by pyruvate carboxylase (which uses ATP) and PEP carboxylkinase (which uses GTP).
pyruvate
removes a phosphate group from fructose 1,6- bisphosphate, producing fructose 6-phosphate. In the third bypass, glucose 6-phosphatase converts glucose 6- phosphate to glucose.
FBPase-1
