Glycolysis Flashcards
Where does glycoloysis occur?
Cytosol
In glycolysis, you start with ________ and end with _________
Start with: 1 molecule of glucose, end w/ 2 molecules of pyruvate
True or False: Pyruvate can be shunted into a ton of different pathways
True, it can go into the citric acid cycle, lactic acid fermentation, gluconeogenesis, or fatty acid synthesis
How many NAD+ are reduced in glycolysis?
2
What is the net gain per glucose molecule in glycolysis?
2
What does adding a phosphate with hexokinase do?
This traps the glucose in the cell, it expends ATP, it also makes it polar (2-)
What is the first irreversible step of glycolysis?
PFK1, this enzyme adds a phosphate to F6P. It is irreversible. It COMMITS IT TO GLYCOLYSIS and is a highly regulated step and is rate limiting.
What molecule feeds into the energy payoff phase of glycolysis?
G3P
For every molecule of G3P that enters the energy payoff, what is produced?
For every 1 G3P, you get 1 NADH, 2 ATP, and 1 Pyruvate
Place the following in order in the energy payoff phase: G3P dehydrogenase Phosphoglycerate mutase Enolase Pyruvate kinase Phosphoglycerate kinase
G3P dehydrogenase Phosphoglycerate kinase Phosphoglycerate mutase Enolase Pyruvate kinase
The “committed step” is a regulatory mechanism employed in many metabolic pathways. One feature of a reaction that occurs at a committed step is that it is irreversible. In the committed step the cell commits to producing products from that pathway. What is considered the commitment step of glycolysis?
The conversion of F6P to F1,6P
Substrate level phosphorylation
In substrate-level phosphorylation, a phosphate group is moved onto a biochemical substrate and then transferred to ADP to form ATP.
What is the only step in glycolysis that involved substrate level phosphorylation?
1,3-bisphosphoglycerate + ADP –> 3 Phosphoglycerate + ATP
What molecules does the cell detect to monitor for energy balance?
AMP (higher in low), ADP (Higher in low), ATP (Higher in high), NADH (Higher in high), Citrate (Higher in high)
Insulin or Glucagon: I upregulate glycolysis
Insulin
Insulin or Glucagon: I downregulate glycolysis
Glucagon
What does Hexokinase do?
Glucose–> G6P
What are the three most regulated steps in glycolysis?
Hexokinase (G->G6P), PFK1 (F6P-> F1,6BP), PK (PEP-> Pyruvate)
How is hexokinase regulated?
It is inhibited by G6P (negative feedback inhibition),
How is glucokinase regulated?
NOT inhibited by G6P. This is because the liver cells with glucokinase are taking in more glucose than your other tissues would.
How is PFK1 regulated?
Downregulated by high levels of ATP and Citrate. Upregulated by high ADP, allosterically regulated by F26BP!!!
What is the role of F26BP?
It upregulates PFK1. Its like super important.
How does insulin regulate glycolysis (what specifically)?
Insulin upregulates PFK2 which is responsible for making F26BP
How does glucagon regulate glycolysis (what specifically)?
Glucagon upregulates Fructose 2,6 bisphosphatase and inhibits PFK2 to decrease the concentration of F26BP.
High ATP and Citrate indicates a high or low energy state and will upregulate or downregulate glycolysis?
They indicate a high energy state and will downregulate glycolysis.
How is pyruvate kinase regulated?
PK is allosterically inhibited by ATP and its inhibited by acetylcoa and fatty acids.
True or False: Citrate indicates low energy in the cell
False, it is high energy
True or false: A high concentration of citrate inhibits glycolysis via negative feedback.
This statement is true. Citrate is a key intermediate in the citric acid cycle, which occurs after glycolysis in aerobic respiration. High levels of citrate indicate that the cell has plenty of raw materials to produce energy through this pathway, so it does not need to continue breaking down glucose through glycolysis.
True or False: Glucokinase is not inhibited by its product
True
What adds a phosphate to glucose as soon as it enters the cell?
Hexokinase (or Glucokinase in liver)
What enzyme is responsible for F6P–> F16P?
PFK1
What enzyme is responsible for F6P–> F26P?
PFK2
What is the following structure?
Pyruvate
Glucose
How many NADH, ATP, and Pyruvate per G3P that enter into the energy payoff phase?
1 NADH, 2 ATP (not net gain), and 1 pyruvate per G3P
Triose Phosphate Isomerase
This enzyme converts DHAP to G3P in the energy investment phase
This step in glycolysis has substrate level phophorylation that is so favorable you dont need ATP
The first step in the energy payoff phase. G3P–> 1,3PG by G#P dehydrogenase
If oxygen is present, where is pyruvate shunted?
Most likely to TCA
In animal cells, if oxygen is not present where does pyruvate go?
Lactic Acid Fermentation
PFK2 shares dual action with which enzyme?
F26Bisphosphatase
