FOM 3.4.2 Flashcards
What percent of daily caloric requirement are from carbs?
55%
What is some of the substrates for glycolysis?
Fructose, galactose, and glucose
What tissue is most dependent on glucose?
The brain
What enzymes are responsible for adding and removal of glycogen branches?
Branching enzyme and debranching enzyme
What is the first reaction needed before glucose-1-phosphate can enter glycolysis?
It needs to be converted into G-6-P by phosphoglucomutase
After G-1-P is released from glycogen and converted to G-6-P what is it converted to by what before being released into the blood?
It is converted it free glucose by glucose-6-phosphatase
At what steps in glycolysis is energy input needed to drive it forward?
The enzymes that input energy required for glycolysis are hexokinase (step 1) and phosphofructokinase (step 3)
What are the glycolytic reactions that produce ATP?
Phosphoglycerate kinase and pyruvate kinase both work and create 2 ATP molecules each.
What is the only reaction that produces NADH from NAD+?
Glyceraldehyde-3-phosphate dehydrogenase
What is a common metal cofactor in kinases?
Magnesium is a common co-factor because it is a divalent cation that stabilizes the phosphates on ATP.
What is the process by which NAD+ is regenerated in the absence of O2? Can this be a good clinical test?
NADH created from the glyceraldehyde 3 phosphate dehydrogenase reaction is then shuttled to react with pyruvate and create lactate. This can be used as a good clinical test because it can measure how well the mitochondria based on the amount of NADH are being used in the ETC.
What is the fate of NADH that is produced from glycolysis?
NADH is shuttled through the malate-aspartate shuttle system or the glycerophosphate shuttle.
What is the importance of tightly regulating glycolysis?
Both glycolysis and gluconeogenesis are occurring in the cytsoplasm of the cell.
What are the reactions that are thought to be essentially irreversible and how does this relate to their free energies?
Hexokinase (reaction 1) has deltaG of 27
Phosphofructokinase (reaction 3) has a deltaG of 26
Pyruvate Kinase (reaction 10) has a deltaG of nearly 14
Because of their large negative Values these reactions are seen as essentially irreversible because it would take a large input of energy to do the reverse reaction.
What is the importance of the reactions with smaller deltaG?
Allows the cell to only have to regulate a few enzymes tightly and the rest will drive it forward
What are the important factors of the pentose phosphate pathway?
It is the main source of NADPH in the cell and it creates ribose sugars
What is the importance of fructose-2,6-bisphosphate?
It acts as a main regulatory molecule for glycolysis. It allosterically activates phosphofructokinase (glycolysis enzyme) and allosterically inhibits fructose bisphosphatase (gluconeogenic enzyme).
What are the roles of PFK-2 and FBPase-2?
These two enzymes control the formation and deformation of F-2,6-BP.
PFK-2 uses ATP and creates it and FBPase2 uses h2o and gets rid of it.
What is the fate of glucose in the liver?
It is taken to the muscle and turned into alanine via a pyruvate intermediate. The alanine in then shuttled back into the into the liver.
What is required for glycogen synthase?
Glucose must react with UTP and create UDP glucose. This can then be added to glycogen by glycogen synthase.
How can deficiency in erthrocyte pyruvate kinase result in anemia?
Red blood cells lack a mitochondria so they rely on glycolysis for the production of their energy. A reduction in the amount of PYK would cause a back up in the other previous reactions. 1,3-BPG could then be changed into 2,3-BPG. Higher levels of this would cause the the release of o2 from the heme.
How could a hexokinase deficiency in erythrocytes be disruptive?
A hexokinase deficiency would cause not enough 2,3-BPG to be made. Thus the hemoglobin would have an increased affinity for the O2 and not want to release it at the correct time.
How can a fructose intolerance be applied to this and what is the mechanism?
Due to a hereditary conditiong that alters the function of aldolase F-1-P cannot be turned into glyceraldehyde. This means that there is a buildup of Fru-1P, which cannot do anything in the cell but take up ATP. This means there is a reduced amount of available ATP that is going to actually be helpful, and can lead to problems like what is demonstrated.
