Glycolysis Flashcards
What is the end product of glycolysis?
2 molecules of pyruvate
Where does glycolysis occurs?
In the cytosol of all tissues/cells
T/F In the first five steps of glycolysis, ATP is consumed and none is produced.
True
When would glycolysis occur?
Glycolysis occurs when the body has high levels of energy or glucose.
What happens in the first step of glycolysis. Name the reactants, products, and enzyme.
In this step, glucose is phosphorylated into glucose-6-phosphate by hexokinase.
Which of the following is not true regarding the first step of glycolysis?
a) Glucose is phosphorylated into glucose-6P by hexokinase.
b) Hexokinase utilizes ATP to phosphorylate glucose thereby producing glucose-6P and ADP
c) Mg2+ is a cofactor required for the phosphorylation of glucose into glucose-6P
d) The phosphorylation of glucose into glucose 6-P is reversible.
d
What happens in the second step of glycolysis. Name the reactants, products, and enzyme.
Glucose 6P is converted into fructose 6P by phosphohexose isomerase
What happens in the third step of glycolysis. Name the reactants, products, and enzyme. What are the cofactor(s) of this step? Does it require ATP?
fructose 6P is converted into fructose 1,6-bisphosphate by phosphofructokinase (PKF-1)
Mg2+
Yes
What is the purpose of step 3 in glycolysis?
To make a symmetrical molecule by phosphorylating C1
What happens in the fourth step of glycolysis. Name the reactants, products, and enzyme.
fructose-1,6-bisphosphate is cleaved into dihydroxyacetone phosphate and glyceraldehyde 3-phosphate by aldolase
What happens in the fifth step of glycolysis. Name the reactants, products, and enzyme.
dihydroxyacetone phosphate is converted into glyceraldehyde 3-phosphate by triose phosphate isomerase.
T/F Glycolysis consist of two phases - one is the preparatory phase in which ATP is utilized and the other is the Pay-Off phase in which oxygen is produced.
True
What happens in step six of glycolysis. Name the reactants, products, and enzyme.
glyceraldehyde 3P is oxidized into 1,3-biphosphoglycerate by glyceraldehyde 3-phosphate dehydrogenase (GAPDH)
What is require in step 6 of glycolysis besides glyceraldehyde (the product) and glyceraldehyde 3-phosphate dehydrogenase (the enzyme)? What is produced besides 1,3-biphosphoglycerate?
This reaction requires the addition of an inorganic compound to glyceraldehyde via oxidation reaction. Meanwhile, NAD+ is reduced into NADH and H+. Meaning we form NADH besides 1,3-biphosphoglycerate
What happens in step seven of glycolysis. Name the reactants, products, and enzyme.
The one of the phosphate groups of 1,3-bisphosphoglycerate is transferred onto ADP to generate ATP and 3-phosphoglycerate by phosphoglycerate kinase
What happens in step eight of glycolysis. Name the reactants, products, and enzyme.
3-phosphoglycerate is converted into 2-phosphoglycerate by phosphoglycerate mutase.
What else besides 3-phosphoglycerate (product) and phosphoglycerate mutase (enzyme) for the formation of 2-phosphateglycerate?
Mg2+. Although this reaction is reversible, Mg2+ is not required in the reverse reaction which converts 2-phosphoglycerate into 3-phosphoglycerate
What happens in step nine of glycolysis. Name the reactants, products, and enzyme.
2-phosphoglycerate is converted into phosohoenolpyruvate through the loss of water by enolase
What happens in step ten of glycolysis. Name the reactants, products, and enzyme.
the phosphate group of phosohoenolpyruvate is transferred by pyruvate kinase onto ADP to generate pyruvate and ATP
What are the cofactors of the last step in glycolysis?
Mg2+ and K+
What factor(s) regulate hexokinase?
concentration of glucose 6-phosphate (G6P). High concentration of G6P will inhibit hexokinase.
How does high concentration of glucose 6-phosphate in the cell affects hexokinase?
it inhibits the activity of hexokinase. Meaning, glucose is not going to be phosphorylated into glucose 6-phosphate.
What factors increase the activity of PFK-1?
F2,6BP, AMP, and ADP
What factors decrease the activity of PFK-1?
ATP and citrate
What factors increase the activity of pyruvate kinase?
F1,6BP and AMP
What factors decrease the activity of pyruvate kinase?
ATP, Acetyl-CoA and Alanine
Enzyme responsible for reducing pyruvate into L-lactate.
lactate dehydrogenase
What is so special about reducing pyruvate into lactate?
The reduction reaction is coupled with the oxidation of NADH to NAD+, which allows the cell to reutilize NAD+ in glycolysis.
How is pyruvate converted into ethanol in fermenting organisms?
- pyruvate undergoes decarboxylation to form acetaldehyde, which is catalyzed by pyruvate decarboxylation. This reaction requires TPP and Mg2+ as cofactors.
- acetaldehyde is reduced into ethanol by alcohol dehydrogenase, which is coupled with the oxidation of NADH into NAD+.
A PET scanning, which is a tool used to diagnose tumors was performed on a patient. The patient’s results indicated that he was exhibiting the Warbug Effect. What does this means?
This means that tumor cells have high rate of glycolysis in which glucose is being fermented into lactate even in the presence of oxygen.
What are two reasons in which the cell would want to send glucose 6-phosphate through the pentose phosphate pathway?
- When the cell requires 5-carbon sugar (or ribose sugar) needed for DNA/RNA or enzymatic synthesis.
- When the cell requires NADPH for fatty acid synthesis and lipid metabolism.
Describe the steps of the pentose phosphate pathway
I. G6P will be oxidized into 6-phosphogluconate, which is coupled with the reduction of NADP+ into NADPH.
II. 6-phosphogluconate undergoes decarboxylation to form ribulose 5-phosphate. This reaction is also coupled with the reduction of NADP+ into NADPH.
III. R5P can be converted into ribose 5 phosphate (which will be use for nucleotide synthesis) or be recycled back into G6P by transketolase/transaldolase (when NADPH is highly required).
Which two enzymes are helpful in reducing reactive oxygen species in the blood? Explain how.
glutathione reductase and glutathione peroxidase
Remember: glutathione peroxidase removes the peroxide species (that result from the oxidation of oxygen) and sends them to glutathione reductase. This enzyme reduces peroxide by transferring the protons onto NADP+ to generate NADPH.
