Glycolysis Summary: Study with Video Lessons, Practice Problems & Examples

Glycolysis is a metabolic pathway that converts glucose into pyruvate, yielding a net production of 2 ATP and 2 NADH. It consists of two phases: the energy-consuming phase (reactions 1-5) and the energy-producing phase (reactions 6-10). Key reactions include phosphorylation, isomerization, and oxidation phosphorylation. The irreversible reactions consume ATP, while the latter phase generates ATP and NADH. Understanding these steps is crucial for grasping cellular respiration and energy production in biological systems.

Glycolysis Summary Concept 1

Everyone. So in this video, let's talk about the glycolysis energy output. Here, we're going to say glycolysis oxidizes glucose to pyruvate, and it produces 2 NADHs and 4 ATP molecules. Now, remember, glycolysis is separated into 2 phases. One phase is energy-consuming, and the other is energy-producing.

We're going to say that in the first part, we go from glucose to Glyceraldehyde 3-Phosphate. This is going to require the consumption of 2 ATP molecules. And then in the second part, spanning reactions 1 to 5 in the second half of glycolysis, which is reactions 6 to 10, we're going to say Glyceraldehyde 3-Phosphate will become Pyruvate. In this process, we're going to make 2 NADHs and 4 ATPs. Now remember, we consumed 2 ATPs initially to make 4 ATPs at the end, so our net production of ATP is just 2 ATP.

So if we take a look here, we'd say that our net production of ATP is 2. We make 0 FADH₂s, and we make 2 NADHs, which will help fuel our 2 pyruvates at the end. Our memory tools that we can utilize here to help us remember all of this are reactions 1-3 are irreversible and use ATP. Okay? Because they're consuming ATP, that's what makes them irreversible.

Now, we're going to say, I irresponsibly ate one-third of a pizza. So here, we're going to refer to pizza because it's a reaction, and we can think of it as a cyclic thing. We're going to say irresponsible, irresponsible, irreversible. "8" means ATP, and then the irreversible reactions that use ATP are reactions 1 and 3, one-third. Then we're going to say reaction 6 produces 2 NADHs, reactions 7 and 10 produce 2 ATP each.

Our memory tools here are that a second six-pack at the weekend. So we're going to say second six-pack. So here, we're going to say "second" is the 2 NADHs produced in reaction 6, "week" is 7 days, and the "end" reaction is reaction 10 of glycolysis, ATP is produced at them. And the memory tool three says, row 10 is one way which means that reaction 10 is irreversible. It only goes to completion.

It only goes one way. It's not a reversible reaction. Right? So keep all this in mind when we're talking about the glycolysis energy output.

Glycolysis Summary Example 1

Which of the following glycolysis reactions produced ATP? Alright. To answer this question correctly, we just have to remember memory tool 2. And, memory tool 2 tells me a second 6 pack at the weekend. So "at" stands for ATP, a week is 7 days long, and the end of the last reaction of glycolysis is reaction 10.

Here, we don't have to worry about the first part, a second 6 pack. That just deals with the number of NADHs that we're producing or involved. But here, we're just talking about ATP. And the memory tool tells me that ATP is produced in reaction 7 and 10. This would mean that my answer would have to be option c.

How many moles of NAD⁺ are required to convert 50.0 g of glucose into pyruvate? How many moles of ATP are produced?

• A. 0.555 mole NAD⁺ and 1.11 mol ATP.
• B. 1.11 mole each of NAD⁺ and ATP.
• C. 0.278 mole NAD⁺ and 0.555 mol ATP.
• D. 0.555 mole each of NAD⁺ and ATP.

Remembering Glycolysis Concept 2

Everyone, let's take a look at the memory tool to help us remember reactions 1 to 5 of glycolysis. Memory tool 4 tells me, Phil invited Phyllis for baked cookies inside. Alright. So here, we're going to say Phil stands for phosphorylation, where we go from glucose to glucose 6-phosphate.

Remember, this consumes 1 ATP to do this. "Invited" is where we're going from glucose to fructose, which are isomers, so this is isomerization. Next, we have "Phyllis p", which stands for phosphorylation, which again requires us to consume another ATP. For reaction 4, "baked cookies" is where we have bond cleavage.

Remember, we cut the bond between carbons 3 and 4, that would give us Glyceraldehyde 6-phosphate and DHAP, which can isomerize between each other, so that would give us reaction 5. So just remember, this is the memory tool you can utilize to remember the types of reactions from 1 to 5 of glycolysis.

Remembering Glycolysis Concept 3

Here, we utilize memory tool 5 to help us remember reactions 6 to 10 of glycolysis. And it is, "Our Pops and Phil tried inventing dry fruity tarts." Alright. So here, we have Glyceraldehyde 3-phosphate. "Our Pops" is oxidation phosphorylation, and we're going to say that's going to give us 1,3-bisphosphoglycerate. Then we're going to say, "Phil tri," so that's a phosphate transfer for reaction 7. We are going from 3-phosphoglycerate (3PG) to 2-phosphoglycerate (2PG); that is isomerization and "venting."

"Dry" for reaction 9 is a dehydration where we're going from 2PG to phosphoenolpyruvate (PEP). And then finally, we're going to have "fruity tarts," where "phosphate stop" sounds like it starts with an F, "transfer tarts," and that is going from PEP to pyruvate. Alright. So just remember, these are the steps that are involved. Remember going in reaction 6, we have a phosphate being attached.

We have NADH being produced. Reaction 7 produces ATP, as does reaction 10. And, this is the memory tool 5 that helps us to remember what's happening in each one of these reactions from 6 to 10 of glycolysis.

Glycolysis Summary Example 2

How many reactions in glycolysis involve an isomerization reaction? Remember, we can utilize memory tools to help us remember this. So remember, memory tool 4 is, "Phil invited Phyllis for baked cookies inside." Everywhere we have an "I" represents an isomerization reaction, so that'd be 12. And then memory tool 5 deals with reactions 6 to 10.

Our pops and Phil tried inviting or inventing dry fruity tarts. So this would be another "I". So we can see that "I" is in 3 places, so 3 reactions in glycolysis deal with an isomerization reaction. That'd give us option C as the correct answer.

Identify each of the following reaction of glycolysis as oxidation (O), isomerization (I), phosphorylation (P), of dehydration (D).

a) ____ Reaction 3

b) ____ Reaction 6

c) ____ Reaction 8

d) ____ Reaction 9

• A. a) P; b) O; c) I; d) D
• B. a) P; b) O; c) D; d) I
• C. a) D; b) O; c) I; d) P
• D. a) D; b) I; c) O; d) P

How many reactions of the glycolysis pathway fall into to the following reaction categories?

a) ____ Isomerization

b) ____ Dehydration

c) ____ Oxidation

d) ____ C–C bond cleavage

e) ____ Phosphate transfer

• A. a) 3; b) 2; c) 1; d) 2; e) 2
• B. a) 2; b) 2; c) 1; d) 1; e) 3
• C. a) 3; b) 1; c) 1; d) 1; e) 2
• D. a) 2; b) 1; c) 2; d) 1; e) 3
• E. a) 3; b) 1; c) 2; d) 2; e) 1