Free Energy
Will energy be released or taken in for an exergonic reaction
Released
Where can it be regulated? (in the body)
Liver and Muscle
where is glycolysis in the cell
cytosol
What steps is glycolysis regulated
- 1
- 3
- 10
What enzyme is used to convert pyruvate to lactate
lactate dehydrogenase
What is free energy difference
change in G
difference between A and B to determine if the reaction will proceed in forward or reverse direction
What is the enzyme that breaks down glycogen
glycogen phosphorylase
What is the energy investment phase and where is ATP used
ATP is spent to begin the reactions, 2 ATP spent to transform glucose for phase 2
1) 1 ATP
3) 1 ATP
How is step 3 regulated
- allosterically inhibited by ATP and citrate
- activated by AMP and fructose-2, 6-biphosphate
- most important regulation step
Where is lactate formed in the body
- muscle
- RBCs
What is Le Chatelier's principle that is applicable to free energy
if concentration on one side of the reaction increases, the direction of the reaction will change to accommodate
glucose-6-P
What reactions don't use the same enzyme to catalyze their reaction in the forward and reverse direction
Reaction 2, fructose-6-P <-> fructose 1,6-biphosphate
Reaction 8/last one phosphoenolpyruvate <-> pyruvate
How is step 1 regulated
- hexokinase inhibited allosterically by rxn product glucose-6-P
- glucokinase: requires high glucose levels, regulated by competitive inhibitor glucokinase regulatory protein
- favours glycogen formation
What do cancer cells do with glycolysis more often than not
What is a coupled reaction
what metabolites activates glycogen phosphorylase in the liver
low ATP levels
low glucose-6-P
low glucose
What is the energy generation phase and where is the ATP/NADH created
ATP is created, (pay off phase)
6) 2 NADH
7) 2 ATP
10) 2 ATP
How is step 10 regulated
pyruvate kinase
- allosterically inhibited by ATP, citric acid and long chained fatty acids- regulated by earlier metabolite fructose-1, 6-biphosphate (feed forward mechanism)
Other examples of anaerobic glycolysis
yeast and goldfish
- low O2
- create 2 ATP
- end product: ethanol
What is an example of a very common coupled reaction
ATP hydrolysis is paired with a reaction to break down glucose
Pi + glucose <-> glucose-6-p + H20 G = 13.8
ATP + H2O <-> ADP + Pi G= -30.5
Coupled:
ATP + glucose <-> ADP + glucose-6-p G = -16.7
What metabolite activates degradation of glycogen
low glucose-6-P
low ATP
high AMP
6 Key principles of metabolic pathway
- flux: rate of flow
- direction: neg change in G needed
- committed step: early in exergonic reaction
- independence of catabolic and anabolic: opposing directions use same enzymes (except 2 and last one)
- regulation: adjust to supply and demand
- compartmentalization: reactions happen in different places
What's the overall net reaction of glycolysis
2 ATP + NAD+ <---> 2 ATP + 2 NADH + 2 pyruvate
what is glucogenesis
used without carbohydrates
- amino acids and other metabolites to create pyruvate with can be metabolized to glucose
- skips the 3 regulatory steps