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38 Cards in this Set

  • Front
  • Back
T/F - Glycolysis is an exergonic reaction.
True - Standardized Change in Gibbs energy is -2,840 kJ/mol.
What are the pathways that glucose can take?
1. Glycolysis
2. Gluconeogenesis
3. Pentose Phosphate Pathway
T/F - Glycolysis is dependent on oxygen.
What tissues use glycolysis as the primary/sole energy source?
1. Sperm
2. Cornea of eye
3. Adrenal Medulla
4. Brain
5. Erythrocytes
What type of transport mechanism allows glucose to enter cells?
Facilitated transport
What are the net end energy molecules from glycolysis?
1 Glucose will yield:

2 H+
2 Pyruvate
Describe the first and second "priming" reactions in glycolysis.
1. Glucose to Glucose 6 Phosphate
2. Fructose 6 Phosphate to Fructose 1,6 bisPhosphate
What does "priming" mean in glycolysis?
Phosphorylating a compound (glucose and fructose 6 phosphate) with ATP invested) to prepare it for subsequent reactions.
Describe glycolysis step 1.
Glucose becomes glucose 6 phosphate with the help of hexokinase. The phosphate comes from one ATP invested in the presence of Mg2+.
Is the first step reversible?
No. It is irreversible!
Describe step 2 of glycolysis.
Glucose 6 phosphate is ISOMERIZED into fructose 6 phosphate with the help of phosphohexose isomerase in the presence of Mg2+.
Is the second step of glycolysis reversible?
Yes. Because of positive standard Gibbs energy change.
Describe step 3 of glycolysis.
Fructose 6 phosphate is phosphorylated to become fructose 1,6 bisphosphate with the help of PFK-1 (phosphofructokinase-1). The phosphate group comes from ATP in the presence of Mg2+.
Is the third step of glycolysis reversible?
No. It is irreversible b/c NEGATIVE delta G standard.
Describe step 4 of glycolysis.
Fructose 1,6 bisphosphate becomes two phosphate triose phosphates: Dihydroxyacetone phosphate (DHAP) and Glyceraldehyde 3 phosphate (G3P). The assisting enzyme is aldose.
Describe step 5 of glycolysis.
DHAP is ISOMERIZED to G3P with the help of triose phosphate isomerase.
Is step 5 of glycolysis reversible?
Yes, but only G3P is the substrate for the next glycolysis enzyme: glyceraldehyde 3 phosphate dehydrogenase (GAPDH)
Describe step 6 of glycolysis.
Each glyceraldehyde 3 phosphate is OXIDIZED to 1,3 bisphosphoglycerate with the help of GAPDH. NADH + H+ is generated from this reaction.
Is step 6 of glycolysis reversible?
Yes due to negative delta G standard.
Where does the hydride ion come from for NAD+?
The hydride ion comes from the carbonyl of GAP, where it is replaced by an inorganic phosphate.
What is the fate of the products from fructose 1,6 bisphosphate.
Carbons lose their identity. Indistinguishable between C1 and C6, C2 and C5, C3 and C4.
Describe the GADPH mechanism.
1.) Thiohemiacetal formation (GAP attaching on the SH)
2.) Oxidation of carbon attached to S, to a carbonyl where the lost H goes to NAD.
3.) NADH / NAD+ exchange (NADH leaves)
4.) E-S lysis by phosphate.
Describe step 7 of glycolysis.
1,3 bisphosphoglycerate and ADP engage in SUBSTRATE LEVEL PHOSPHORYLATION to yield 3 phosphoglycerate and ATP, in the presence of phosphoglycerate kinase.
Is step 7 of glycolysis reversible?
Yes due to negative you know what.
Describe step 8 of glycolysis.
3 phosphoglycerate MUTATES TO 2 phosphoglycerate in the presence of phosphoglycerate mutase.
Is step 8 of glycolysis reversible?
Yes with POSITIVE delta G standard. Wierd
Mechanism of phosphoglycerate mutase enzyme.
1. Unphosphorylated histidine of enzymes become phosphorylated by 2,3 bisphosphoglycerate thus is PRE-PRIMED.
2. Phosphoenzyme (phosphoglycerate mutase) will phosphorylate C2 on 3-phosphoglycerate to make it 2,3 bisphosphoglycerate.
3. Then it will take the C3 phosphate group off.
Describe step 9 of glycolysis.
2 bisphosphoglycerate is ENOLATED to become phosphoenolpyruvate (PEP) with the help of enolase. Water will leave the reaction.
Is step 9 of glycolysis reversibe?
Describe step 10 of glycolysis.
PEP is and ADP engage in SUBSTRATE LEVEL PHOSPHORYLATION yielding Pyruvate and ATP, with the help of pyruvate kinase.
Is step 10 of glycolysis reversible?
NOOOOOOOOOO Biatch! Step 1,3, and 10 are NONREVERSIBLE.
What is the primary enzyme regulator of glycolysis?
Phosphofructokinase 1 (PFK-1)
What is the secondary regulating enzyme of glycolysis?
Pyruvate kinase (PK)
Pyruvate is formed in what state?
The enol state from PEP.
What does the initial form of pyruvate become?
TAUTOMERIZES to keto state.
What is the net change in NADH in anaerobic glycolysis?
Zero b/c 2 NADH becomes 2 NAD's from pyruvate to lactate.
Why is it important that al the glycolytic intermediates from G6P to PEP are phosphorylated?
1. Charge (P) on a molecule keeps it from crossing the plasma membrane. (compartmentalization)
2. Energy is stored in high energy phosphate bonds (conservation)
3. Specificity and binding energy to enzymes ar both increased by charged phosphate groups.
Is the anaerobic reduction of pyruvate to lactate reversible?
YES it is reversible.