Exam 3: Carbohydrate Metabolism Flashcards
(23 cards)
Name the reactants and number of which are involved in glycolysis.
1 Glucose 2 ATP 2 NAD+ 2 Pi 4 ADP
Name the end products and number of which are involved in glycolysis.
2 Pyruvate
4 ATP
2 NADH
In glycolysis, glucose is ultimately converted into _________.
…pyruvate.
Where does glycolysis occur?
In the cytosol of the cell.
Describe where the preparatory phase starts and ends.
It begins with the phosphorylation of glucose and ends with the production of glyceraldehyde 3-phosphate.
Describe where the payoff phase begins and ends.
It begins with the oxidative conversion glyceraldehyde 3-phosphate and ends with the production of pyruvate and the second production of ATP.
Properly trace the reactions through glycolysis.
Glucose > Glucose-6P > Fructose-6P > Fructose-1,6P > Glyceraldehyde-3P + Dihydroxyacetone phosphate > (2) Glyceraldehyde-3P > (2) 1,3-BPG > (2) 3-Phosphoglycerate > (2) 2-Phosphoglycerate > (2) Phosphoenolphyruvate > (2) Pyruvate
Properly trace the enzymes that drive the reactions through glycolysis.
- Hexokinase
- Phosphohexose isomerase
- Phosphofructokinase-1
- Aldose
- Triose phosphate isomerase
- Glyceraldehyde 3-phosphate dehydrogenase
- Phosphoglycerate kinase
- Phosphoglycerate mutase
- Enolase
- Pyruvate kinase
What is the first committed step of glycolysis and why?
Step 3, the second priming reaction of fructose 6-phosphate to fructose 1,6-bisphosphate. This is the first committed reaction because all products previously may have been utilized in other reactions, but once fructose 1,6-bisphosphate is produced, it must continue through glycolysis.
List the reactions that use ATP in glycolysis.
Steps 1., 3., 7., and 10.
What are fermentation reactions?
Reactions that occur to generate ATP without the consumption of oxygen.
What is the Cori Cycle?
The process by which lactate from lactic acid fermentation is cycled though the blood to the liver and, with the aid of ATP, synthesizes glucose in gluconeogenesis during recovery.
What enzyme are humans incapable of producing that would allow us to ferment alcohol?
Pyruvate decarboxylase.
Where do glycolysis and gluconeogenesis respectively occur?
Glycolysis occurs mainly in the brain and muscles, whereas gluconeogenesis occurs mainly in the liver.
Explain bypass reactions in gluconeogenesis.
There are steps in glycolysis that are irreversible which must be bypassed in gluconeogenesis.
Name the products and reactants of the three bypass reactions.
- Pyruvate > Oxaloacetate > Phosphoenolpyruvate
- Fructose 1, 6 - Bisphosphate > Fructose 6 - Phosphate + Pi
- Glucose 6 - Phosphate > Glucose + Pi
Where does gluconeogenesis occur?
Within the cytosol and mitochondria.
Why must oxaloacetate be converted into malate or PEP before being exported?
There is no transporter for oxaloacetate in mitochondria.
What is the role of glycogenin?
To generate the protein core of glycogen and catalyzes the addition of the first 8 residues.
What is the role of glycogen-branching enzyme?
To transfer 6 to 7 glucose monomers from the growing chain to the C6 hydroxyl group of a glucose on the same chain or another chain to make an a1-6 connection.
What is the role of glycogen synthase?
To add more glucose monomers to both branches.
What is the function of the pentose phosphate pathway?
Generates Nucleotides, Coenzymes, DNA, and RNA while along the way the reduction of NADP+ is needed for the generation of fatty acids, sterols, and steroids that can aide in the repair in oxidative damage.
What does the pentose phosphate pathway use to generate the main products of NADPH and ribose 5-phosphate?
Glucose 6-phosphate.
