7.2.1 Glycolysis

• Glycolysis releases energy in the form of ATP and NADH
• Glycolysis occurs in the cytoplasm of cells.
• Glycolysis consists of two main phases: energy investment and energy payoff.
• Match the phase with its net ATP production:

  Energy Investment ↔️ -2 ATP

  Energy Payoff ↔️ +4 ATP
• During the energy investment phase, glucose is phosphorylated using ATP
• Outline the energy investment phase of glycolysis:

  1️⃣ Phosphorylation of glucose to glucose-6-phosphate

  2️⃣ Isomerization of glucose-6-phosphate to fructose-6-phosphate

  3️⃣ Second phosphorylation to fructose-1,6-bisphosphate

  4️⃣ Cleavage of fructose-1,6-bisphosphate into G3P and DHAP

  5️⃣ Isomerization of DHAP to G3P
• Outline the energy payoff phase of glycolysis:

  1️⃣ Oxidation and phosphorylation of G3P to 1,3-bisphosphoglycerate

  2️⃣ ATP synthesis from 1,3-bisphosphoglycerate

  3️⃣ Isomerization of 3-phosphoglycerate to 2-phosphoglycerate

  4️⃣ Dehydration of 2-phosphoglycerate to PEP

  5️⃣ Final ATP synthesis from PEP
• Match the enzyme with its function in glycolysis:

  Hexokinase ↔️ Phosphorylates glucose

  Phosphoglucose isomerase ↔️ Isomerizes glucose-6-phosphate

  Phosphofructokinase-1 ↔️ Phosphorylates fructose-6-phosphate

  Aldolase ↔️ Cleaves fructose-1,6-bisphosphate

  Triose phosphate isomerase ↔️ Isomerizes DHAP to G3P
• In muscle cells, glycolysis breaks down glucose to produce pyruvate
• The step-by-step process of glycolysis is divided into two phases: energy investment and energy payoff.
• Arrange the steps of the energy investment phase of glycolysis in the correct order.

  1️⃣ Phosphorylation of Glucose

  2️⃣ Isomerization

  3️⃣ Second Phosphorylation

  4️⃣ Cleavage

  5️⃣ Isomerization of DHAP
• What is the net ATP production from glycolysis?

  2 ATP
• Glyceraldehyde-3-phosphate dehydrogenase produces NADH during glycolysis.
• The final enzyme in glycolysis that forms pyruvate and ATP is pyruvate kinase
• Match the enzyme with its role in glycolysis.

  Hexokinase ↔️ Phosphorylates glucose

  Phosphoglucose Isomerase ↔️ Converts glucose-6-phosphate to fructose-6-phosphate

  Phosphofructokinase-1 ↔️ Phosphorylates fructose-6-phosphate

  Aldolase ↔️ Cleaves fructose-1,6-bisphosphate

  Pyruvate Kinase ↔️ Forms pyruvate and ATP
• For each molecule of glucose processed, glycolysis produces two molecules of pyruvate, two net ATP, and two NADH.
• Pyruvate can enter the Krebs cycle under aerobic
• Where does glycolysis occur in the cell?

  Cytoplasm
• Glycolysis can occur under both aerobic and anaerobic conditions.
• Match the cellular location with its role in glycolysis.

  Cytoplasm ↔️ Location of glycolysis

  Cytosol ↔️ Contains glycolytic enzymes
• How many ATP molecules are consumed in the energy investment phase of glycolysis?

  2 ATP
• The net ATP production from glycolysis is 2
• Arrange the steps of the energy payoff phase of glycolysis in the correct order.

  1️⃣ Oxidation and Phosphorylation

  2️⃣ ATP Synthesis

  3️⃣ Isomerization of 3-Phosphoglycerate

  4️⃣ Dehydration

  5️⃣ Final ATP Synthesis
• Which enzyme produces NADH during the energy payoff phase of glycolysis?

  Glyceraldehyde-3-phosphate dehydrogenase
• The final ATP molecule in glycolysis is formed by pyruvate kinase
• 3-Phosphoglycerate is isomerized to 2-phosphoglycerate by phosphoglycerate mutase
• What is 2-phosphoglycerate dehydrated to form in glycolysis?

  Phosphoenolpyruvate
• Phosphoenolpyruvate donates a phosphate to ADP to form pyruvate and ATP
• Steps in the energy investment phase of glycolysis

  1️⃣ Phosphorylation of glucose

  2️⃣ Isomerization of glucose-6-phosphate

  3️⃣ Second phosphorylation of fructose-6-phosphate

  4️⃣ Cleavage of fructose-1,6-bisphosphate

  5️⃣ Isomerization of DHAP
• Glucose is phosphorylated to form glucose-6-phosphate using hexokinase
• Which enzyme isomerizes glucose-6-phosphate to fructose-6-phosphate?

  Phosphoglucose isomerase
• Fructose-1,6-bisphosphate is cleaved into G3P and DHAP by the enzyme aldolase
• What enzyme converts DHAP to G3P to ensure all glucose is processed to G3P?

  Triose phosphate isomerase
• Glyceraldehyde-3-phosphate is oxidized and phosphorylated to form 1,3-bisphosphoglycerate
• Which enzyme catalyzes the transfer of a phosphate from 1,3-bisphosphoglycerate to ADP, forming ATP?

  Phosphoglycerate kinase
• Match the enzyme with its role in glycolysis:

  Hexokinase ↔️ Phosphorylates glucose to glucose-6-phosphate

  Phosphoglucose Isomerase ↔️ Converts glucose-6-phosphate to fructose-6-phosphate

  Phosphofructokinase-1 ↔️ Phosphorylates fructose-6-phosphate to fructose-1,6-bisphosphate

  Aldolase ↔️ Cleaves fructose-1,6-bisphosphate into G3P and DHAP

  Triose Phosphate Isomerase ↔️ Converts DHAP to G3P

  Glyceraldehyde-3-Phosphate Dehydrogenase ↔️ Oxidizes G3P to 1,3-bisphosphoglycerate, producing NADH

  Phosphoglycerate Kinase ↔️ Transfers phosphate from 1,3-bisphosphoglycerate to ADP, forming ATP

  Phosphoglycerate Mutase ↔️ Converts 3-phosphoglycerate to 2-phosphoglycerate

  Enolase ↔️ Dehydrates 2-phosphoglycerate to phosphoenolpyruvate

  Pyruvate Kinase ↔️ Transfers phosphate from PEP to ADP, forming ATP and pyruvate
• What are the primary products of glycolysis for each glucose molecule processed?

  Pyruvate, ATP, NADH
• The key enzymes in glycolysis regulation are hexokinase, phosphofructokinase-1, and pyruvate kinase
• Insulin stimulates glycolysis, while glucagon inhibits it
• Where does glycolysis occur in the cell?

  Cytoplasm