Glycolysis III Flashcards
Which enzyme in glycolysis requires a aldolase residue in its active site?
Hexokinase
Glucose –> Glucose-6-phosphate
Which steps of glycolysis are irreversible?
Steps 1, 3, and 10
Glucose –> Glucose-6-phosphate (hexokinase)
Fructose-6-phosphate –> Fructose-1,6-bisphosphate (phosphofructokinase-1)
Phosphoenolpyruvate –> Pyruvate (pyruvate kinase)
Which steps of glycolysis require ATP?
Steps 1 & 3
Glucose –> Glucose-6-phosphate (hexokinase)
Fructose-6-phosphate –> Fructose-1,6-bisphosphate (phosphofructokinase-1)
What do hexokinase, phosphofructokinase-1, phosphoglycerate kinase, and pyruvate kinase have in common?
They all catalyze phosphoryl transfers, meaning that they are transferases
Which enzymes of glycolysis are transferases?
- Hexokinase
- Phosphofructose kinase-1
- Phosphoglycerate kinase
- Pyruvate
Which enzymes of glycolysis are isomerases?
- Phosphoglucose isomerase
- Triose phosphate isomerase
What do phosphoglycose isomerase and triose phosphate isomerase have in common?
They both catalyze aldo-keto isomerization, making them isomerases
To what class of enzymes does aldolase belong?
Aldolase is a type of lyase
What class of enzymes catalyze the cleavage of C-C, C-O, C-N, and other bonds by elimination, leaving double bonds or rings, or conversely adding groups to double bonds?
Lyases (e.g., decarboxylases, aldolases, dehydratase)
What class of enzymes catalyze the transfer of atoms or groups between two molecules?
Transferases (e.g., kinases, transferases)
What class of enzymes catalyze isomerization reactions?
Isomerases (e.g., phosphohexoisomerase)
What class of enzymes catalyzes the transfer of electrons or hydrogen atoms from one molecule to another?
Oxidoreductases (e.g, hydrogenases, oxidases)
What enzymes of glycolysis fall under the class of enzymes known as oxidoreductases?
- Glyceraldephyde-3-phosphate dehydrogenase
Mutase is a subtype of the _________________ class of enzymes.
Isomerase
What enzymes of glycolysis are mutases?
Phosphoglycerate mutase
What are the 10 metabolic intermediates of glycolysis (in order)?
- Glucose
- Glucose-6-phosphate
- Fructose-6-phosphate
- Fructose-1,6-bisphosphate
- Glyceraldehyde-3-phosphate & dihydroxyacetone phosphate
- 1,3-bisphosphate glycerate
- 3-phosphate glycerate
- 2-phosphate glycerate
- Phosphenolpyruvate
- Pyruvate
What is the name of the metabolic pathway by which glucose is broken down into two molecules of pyruvate?
Glycolysis
_____________________ was the first metabolic pathway elucidated.
Glycolysis
In what cell types is glycolysis the sole energy source?
Brain cells
Red blood cells
What are sources of glucose?
- Dietary starch & simple sugars
- Glycogen stores in the liver & muscle
- Gluconeogenesis
Glycolysis consists of two phases. What are they?
- Energy investment
- Energy recovery
What is the overall equation for glycolysis?
Glucose + 2 NAD+ + 2 ADP + 2 Pi –> 2 pyruvate + 2 NADH + 2 ATP + 2 H+ + 2 H2O
What is the Pasteur effect?
The Pasteur effect refers to a phenomenom in which increased rates of glycolysis occur under anaerobic conditions and decreased rates of glycolysis occur under aerobic conditions
What is the Warburg effect?
A phenomenom in which rates of glycolysis increase significantly in cancer cells - upwards to 10X faster than normal cells even while in the presence of oxygen, and as a result, more aggressive tumors have higher rates of glycolysis
What is the role of hypoxia-induced transcription factor in the Warburg effect?
Cancer cells undergo rapid proliferation. As cell proliferation rates increase, oxygen consumption within tissues also increases, leading to hypoxia. Increased rates of hypoxia lead to the activation of hypoxia-induced transcription factor-1, which then increases transcription of vascular endothelial growth factor (VEGF). VEGF increases oxygen delivery to cells and stimulates angiogenesis (i.e., the creation of new blood vessels). Therefore, cancer cells stimulate increased rates of oxygen by stimulating hypoxia-induced transcription factor-1
How does positron emission tomography work?
A patient is given an IV solution of 18fluorine doxyglucose (FDG), which is an analog of glucose. After the first rate-determining step, FDG is converted into FDG-6-phosphate, which cannot be further metabolized. Its negative charge traps it in cells, and its accumulation is proportional the cellular glycolytic rates. 18F enuts a positron that can be picked up by positron emission tomography. Therefore, tissues and/or cells with higher positron emissions are likely to be sites of cancer or other abnormal growths
What are the 10 enzymes that function in glycolysis (in order)?
- Hexokinase
- Phosphohexoisomerase
- Phosphofructokinase-1
- Aldolase
- Triose phosphate isomerase
- Glyceraldehyde-3-phosphate dehydrogenase
- Phosphoglycerate kinase
- Phosphoglycerate mutase
- Enolase
- Pyruvate kinase
Which steps of glycolysis produce ATP?
Steps 7 & 9
1,3-bisphosphate glycerate –> 3-phosphoglycerate (phosphoglycerate kinase)
Phosphoenolpyruvate –> pyruvate (pyruvate kinase)
An intermediate of glycolysis includes 2,3-bisphophoglycerate in the conversion of 3-phosphoglycerate to 2-phosphoglycerate. 2,3-bisphosphglycerate is an allosteric inhibitor of hemoglobin by decreasing its affinity for what molecule?
Molecular oxygen
