Steps of Glycolysis Reactions Explained - Animation - SUPER EASY

Summary

Glycolysis is a crucial cellular process that converts glucose into ATP, the cell's energy currency. Through 10 enzymatic reactions, glucose is transformed into pyruvate, yielding 2 ATPs and 2 NADHs per glucose molecule. This pathway begins with energy-consuming steps, then transitions to an energy-producing phase, culminating in the formation of pyruvate and ATP. Glycolysis can be influenced by other cellular substrates, impacting the net ATP production. It plays a vital role in supplying energy for life-sustaining biochemical processes.

Takeaways

• 🔋 Biological organisms need energy to survive, and glycolysis is one way cells transform glucose into ATP.
• 🧪 Glycolysis occurs in the cytosol and involves 10 enzymatic reactions that convert glucose into pyruvate.
• 🔥 Glycolysis produces ATP and NADH, which can be further used to generate additional ATP.
• 💥 The first step of glycolysis involves a kinase adding a phosphate to glucose, forming glucose-6-phosphate in an irreversible reaction.
• 🔄 Glucose-6-phosphate is isomerized to fructose-6-phosphate, and another kinase reaction forms fructose-1,6-bisphosphate.
• ✂️ A lyase reaction splits fructose-1,6-bisphosphate into two 3-carbon sugars: dihydroxyacetone phosphate and glyceraldehyde-3-phosphate.
• ⚡ Steps 6-10 of glycolysis are energy-producing, where 2 NADHs and 4 ATPs are generated for each glucose molecule.
• 🔄 Phosphates are transferred in several steps, ultimately leading to the formation of pyruvate and ATP.
• 💧 Water is removed from 2-phosphoglycerate in a lyase reaction to form phosphoenolpyruvate, leading to the final ATP production.
• 🔋 Glycolysis is a key contributor to ATP production, which is vital for many biochemical pathways essential for life.

Q & A

What is the primary function of glycolysis?

Glycolysis is a metabolic pathway that converts glucose into pyruvate while generating ATP, which is a form of biochemical energy required by cells.

How many ATPs are produced during the glycolysis process?

Glycolysis produces a net gain of 2 ATPs per glucose molecule, but it consumes 2 ATPs during the process, so the net production is 2 ATPs after accounting for the consumed ATPs.

What is the role of NADH in glycolysis?

NADH is produced during the oxidation of glyceraldehyde-3-phosphate and can be used later in cellular respiration to generate more ATP.

How many enzymatic reactions are involved in glycolysis?

There are a total of 10 enzymatic reactions involved in glycolysis.

What is the significance of the kinase reaction that adds a phosphate to glucose?

The kinase reaction that adds a phosphate to glucose to form glucose-6-phosphate is significant because it is one of the two energy-consuming steps in glycolysis and is an irreversible reaction.

What happens in the isomerization step of glycolysis?

In the isomerization step, glucose-6-phosphate is rearranged into fructose-6-phosphate by rearranging covalent bonds.

How does the conversion of fructose-6-phosphate to fructose-1,6-bisphosphate occur?

This conversion occurs when a kinase removes a phosphate group from ATP and adds it to fructose-6-phosphate, forming fructose-1,6-bisphosphate.

What is the result of the lyase reaction in glycolysis?

The lyase reaction splits fructose-1,6-bisphosphate into two 3-carbon sugars: dihydroxyacetone phosphate and glyceraldehyde-3-phosphate.

What is the purpose of the kinase reaction that forms ATP and 3-phosphoglycerate?

This kinase reaction transfers a phosphate from 1,3-bisphosphoglycerate to ADP, forming ATP and 3-phosphoglycerate, which is a part of the energy-producing phase of glycolysis.

How does the conversion of 2-phosphoglycerate to phosphoenolpyruvate occur?

The conversion occurs through a lyase reaction that removes a water molecule from 2-phosphoglycerate.

What is the final product of glycolysis and what is its fate in aerobic respiration?

The final product of glycolysis is pyruvate, which can be used in aerobic respiration to produce more energy for the cell.

How can other sugars enter the glycolysis pathway and what is the impact on ATP production?

Other sugars can enter the glycolysis pathway at different points, affecting the net number of ATPs produced. For example, when glucose 6-phosphate is produced from glycogen breakdown, it can enter glycolysis at the second step, requiring one less ATP.

Outlines

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🌿 Glycolysis: Energy Conversion in Cells

Glycolysis is a critical metabolic pathway in cells that converts glucose into energy-rich molecules like ATP. This process occurs in the cytosol and involves 10 enzymatic reactions. Starting with glucose, it is first converted to glucose-6-phosphate, consuming one ATP in an irreversible reaction. Fructose-6-phosphate is then formed via an isomerization step. A second ATP is consumed to create fructose-1,6-bisphosphate. The pathway then splits fructose-1,6-bisphosphate into two 3-carbon sugars. These are then oxidized to 1,3-bisphosphoglycerate, producing two NADH molecules. Subsequent steps regenerate ATP and transform the intermediates into pyruvate. The net gain from glycolysis is 2 pyruvate molecules, 2 ATP, and 2 NADH per glucose molecule. Glycolysis can also be influenced by other cellular reactions, such as glycogen breakdown, which can alter the ATP yield. This pathway is essential for the production of ATP, which fuels various biochemical processes vital to life.

Keywords

💡Glycolysis

Glycolysis is a metabolic pathway that occurs in the cytoplasm of cells, where glucose is broken down into pyruvate, generating energy in the form of ATP. It is a central process in cellular respiration and is essential for life as it provides a rapid source of energy. In the script, glycolysis is described as a series of 10 enzymatic reactions that convert one glucose molecule into two pyruvate molecules, along with the production of ATP and NADH.

💡ATP

ATP, or adenosine triphosphate, is the primary energy currency of cells. It is a molecule that stores and transfers chemical energy within cells. In the context of the video, ATP is both consumed and produced during glycolysis. It is used to power various cellular processes, and its production is a key outcome of glycolysis, as highlighted by the script's mention of the net gain of 4 ATPs per glucose molecule broken down.

💡NADH

NADH, or nicotinamide adenine dinucleotide, is a coenzyme that plays a critical role in cellular respiration. It is involved in the transfer of electrons during oxidation-reduction reactions. In the script, NADH is produced during the oxidation of glyceraldehyde-3-phosphate, and it can be used later in the electron transport chain to generate more ATP, illustrating its importance in energy production.

💡Enzymatic reactions

Enzymatic reactions are biochemical processes that are catalyzed by enzymes, which are proteins that speed up chemical reactions without being consumed in the process. The script describes glycolysis as involving a series of 10 enzymatic reactions, each facilitated by a different enzyme, that transform glucose into pyruvate and generate ATP.

💡Cytosol

The cytosol is the liquid portion of a cell's cytoplasm where many metabolic reactions occur. In the script, glycolysis takes place in the cytosol, emphasizing that this process is not confined to any specific organelle but occurs in the cell's main body.

💡Glucose

Glucose is a simple sugar and a primary source of energy for cellular processes. It is the starting molecule in glycolysis, as mentioned in the script, where it is converted into pyruvate and other energy-rich molecules like ATP and NADH.

💡Pyruvate

Pyruvate is a key intermediate in several metabolic pathways, including glycolysis. It is the end product of glycolysis, as described in the script, where one glucose molecule is converted into two pyruvate molecules. Pyruvate can be further metabolized in the mitochondria for additional energy production.

💡Irreversible reaction

An irreversible reaction is one that does not readily proceed in the reverse direction under normal physiological conditions. The script identifies the first two steps of glycolysis, where kinase reactions add phosphate groups to glucose, as irreversible reactions, indicating that these steps move the pathway forward in one direction only.

💡Energy consumption

Energy consumption in a biochemical context refers to the use of ATP to drive certain reactions. The script mentions that two steps in glycolysis are energy-consuming, as they require the input of ATP to proceed, highlighting the investment of energy needed to initiate the process.

💡Substrates

Substrates are the molecules upon which enzymes act to catalyze chemical reactions. In the context of the script, substrates like glucose and fructose-6-phosphate are mentioned as they enter into the enzymatic reactions of glycolysis, being transformed into different molecules to produce energy.

💡Biochemical pathways

Biochemical pathways are series of chemical reactions that occur within organisms, involving enzymes and substrates. The script discusses how ATP, a product of glycolysis, is essential for many biochemical pathways, emphasizing the interconnectedness of metabolic processes within cells.

Highlights

Glycolysis is a cellular pathway for converting glucose into ATP.

Glucose is converted into pyruvate through 10 enzymatic reactions.

Glycolysis occurs in the cytosol of the cell.

ATP and NADH are produced alongside pyruvate.

The first step of glycolysis is an irreversible kinase reaction.

Glucose-6-phosphate is formed by adding a phosphate group to glucose.

Isomerase reaction rearranges covalent bonds to form fructose-6-phosphate.

A second kinase reaction consumes ATP to form fructose-1,6-bisphosphate.

Fructose-1,6-bisphosphate is split into two 3-carbon sugars by a lyase reaction.

Glyceraldehyde-3-phosphate is formed and represents the metabolic intermediate of glucose.

Two ATPs are consumed in the preparatory phase of glycolysis.

The energy-producing phase of glycolysis begins with the oxidation of glyceraldehyde-3-phosphate.

Each oxidized glyceraldehyde-3-phosphate produces 1 NADH.

A kinase reaction forms ATP and 3-phosphoglycerate in a reversible step.

A mutase reaction rearranges the phosphate group on 3-phosphoglycerate.

Phosphoenolpyruvate is formed by a lyase reaction removing water from 2-phosphoglycerate.

The final step of glycolysis produces ATP and pyruvate from phosphoenolpyruvate.

For each glucose, glycolysis yields 2 pyruvate molecules, 4 ATPs, and 2 NADHs.

Pyruvates and NADHs can be used in aerobic respiration for more energy.

Substrates from other reactions can enter glycolysis at various points.

Glycogen breakdown produces glucose 6-phosphate, which enters glycolysis at the second step.

Different sugars entering glycolysis affect the net ATP production.

ATP produced by glycolysis is crucial for many biochemical pathways and life.

Glycolysis significantly contributes to the ATP pool for essential biological pathways.

Transcripts

Biological organisms require energy to survive.

Glycolysis is one of the pathways cells use to transform

sugars like glucose into biochemical energy in the form of ATP.

In the cytosol of the cell, glycolysis converts glucose into pyruvate,

through a series of 10 enzymatic reactions.

This process produces ATP, along with other products, such as NADH,

that can be used later to produce even more ATP for the cell.

Let’s watch as these enzymes oxidize 1 glucose molecule

into 2 pyruvate molecules.

First, a kinase reaction adds a phosphate onto glucose to form glucose-6-phosphate.

This is one of 2 energy consumption steps and is an irreversible reaction.

Next, an isomerase reaction converts

glucose-6-phosphate into fructose-6-phosphate

by rearranging covalent bonds.

Another kinase removes a phosphate group from ATP

and gives it to fructose-6-phosphate

to form fructose-1,6-bisphosphate.

This is the 2nd energy consumption step,

and an irreversible reaction.

In the 4th step of glycolysis,

a lyase reaction splits the 6-carbon fructose-1,6-bisphosphate

into two 3-carbon sugars,

dihydroxyacetone phosphate,

and glyceraldehyde-3-phosphate.

The dihydroxyacetone phosphate is rearranged by another isomerase

to form a 2nd glyceraldehyde-3-phosphate.

At this point in glycolysis,

glucose has been metabolized into two glyceraldehyde-3-phosphates,

and 2 ATPs have been consumed.

The next five steps of glycolysis are the energy producing phase.

In step 6,

both glyceraldehyde-3-phosphates are oxidized

to 1,3-bisphosphoglycerate by a dehydrogenase.

This step produces 1 NADH

for each oxidized glyceraldehyde-3-phosphate

for a total of 2 NADHs.

These NADHs are later used to produce more ATP for the cell.

In step 7,

a kinase transfers a phosphate

from 1,3-bisphosphoglycerate

to ADP to form ATP and 3-phosphoglycerate.

This step is reversible even though ATP is formed.

The next step involves a mutase reaction,

that moves the phosphate on the 3rd carbon of 3-phosphoglycerate,

to the 2nd carbon position to form 2-phosphoglycerate.

In step 9,

a lyase reaction removes water from 2-phosphoglycerate

to form phosphoenolpyruvate.

In the final step of glycolysis,

a kinase reaction removes the phosphate group from phosphoenolpyruvate

and donates it to ADP to form ATP and pyruvate.

Like reactions 1 and 3, this step is irreversible.

At this point, 2 pyruvate molecules,

4 ATPs

and 2 NADHs are formed for each glucose that was broken down in glycolysis.

The pyruvates and NADHs

could be used in aerobic respiration to produce more energy for the cell.

Here we depict glycolysis as a closed process.

But in cells, substrates produced by other reactions

can enter glycolysis at different points.

For example, when an animal breaks down glycogen,

glucose 6-phosphate is produced

and can then enter the glycolysis pathway at the 2nd step.

Importantly, this means one less ATP is required for the pathway

because the 1st ATP consuming step is skipped.

Other sugars can also enter the glycolysis pathway at different points,

each having a different effect on the net number of ATPs that are produced by glycolysis.

These ATPs are important energy molecules required for many biochemical pathways

and ultimately life itself.

Glycolysis is a major contributor to the pool of ATP used in these pathways,

pathways that are essential to the survival of biological organisms.