Discover chemiosmosis. Find the chemiosmosis definition, chemiosmosis steps, and chemiosmosis diagram. Learn about the role of chemiosmosis in the body.
Updated: 02/15/2022
Chemiosmosis | Gradient, Diagram, Process & Steps
What is Chemiosmosis?
Chemiosmosis is the movement of ions from high concentration to low concentration through a selectively permeable membrane. Chemiosmosis depends on the diffusion principle. Diffusion is the movement of particles from high concentration to low concentration, in other words, the movement of particles down their concentration gradient . A gradient means that the concentration of particles is greater on one side than on the other.
There are numerous examples of diffusion in the real world such as the following:
- A drop of ink submerged in a cup of water will diffuse and affect the color of the water.
- Sugar dissolves and sweetens the water without the need for stirring.
- The detecting of an odor of perfume sprayed into the air.
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There are also many diffusion processes that occur in living organisms:
- Toxic and waste substances are eliminated from the human body through diffusion.
- The exchange of gases within the two lungs.
- In the kidneys, the diffusion of waste materials, salt, and water.
- The transportation of molecules within plant and animal cells requires diffusion.
There are three types of transport:
- Simple diffusion: The movement of particles from high concentration gradient to the low concentration gradient
- Osmosis: The process in which solvent molecules move across a semipermeable barrier from a less concentrated solution to a more concentrated one.
- Facilitated diffusion: The movement of particles from higher concentration gradient to lower concentration gradient with the help of transport proteins.
These three types are passive which means they don't require energy as substances move down their concentration gradient, unlike active transport which is the movement of substances from lower concentration to higher concentration, that is, movement of substances against their concentration gradient. Active transport requires energy to allow substances to move against a concentration gradient.
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What Is Diffusion?
Chemiosmosis is the process of a molecule moving from high to low concentration, based on its charge and concentration inside a cell. This sounds pretty complicated. So, before talking about chemiosmosis, it will be important to understand a basic rule of the world: diffusion.
Diffusion is when anything moves from high concentration to low concentration. Think about food coloring in a jar of water. When the food coloring is first added to the water, it is concentrated in the center, but because there is less food coloring in other parts of the water, over time the food coloring spreads out or diffuses.
There are many more examples, such as delicious smells wafting from the kitchen during a holiday meal or warm air moving outwards from the house during the winter. The examples are so ubiquitous because diffusion is everywhere! Everything always moves from where there is more to where there is less. Check out the pictures of food coloring diffusing through a beaker of water.
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Chemiosmosis Model
The chemiosmosis is a coupling model in the mitochondria and its process is discussed below in detail.
Chemiosmosis Process
Chemiosmosis is the movement of ions according to the electrochemical gradient over a semipermeable membrane structure. Chemiosmosis substance moving from high to low concentration, and also moving from high charge to low charge. A gradient of electrochemical potential, generally for an ion that may travel across a membrane, is referred to as an electrochemical gradient. The chemiosmosis process is directly related to the synthesis of ATP (which stands for adenosine triphosphate) during cellular respiration by the movement of hydrogen ions across a membrane. Hydrogen ions (protons) will diffuse from a high proton concentration area to a low proton concentration area, that is to say, hydrogen ions will move down their proton gradient.
The generation of ATP takes place in the energy factory of the cell which is the mitochondria; the mitochondria consists of various structures including the inner membrane, outer membrane, and matrix which is a space within the inner membrane.
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Cellular respiration takes place in subsequent three stages: glycolysis, Krebs cycle (citric acid cycle), and electron transport chain. Glycolysis takes place in the cytoplasm while the citric acid cycle takes place in the matrix and the electron transport chain happens at the inner mitochondrial membranes. The citric acid cycle requires pyruvate, which is delivered into the mitochondrial matrix during glycolysis. The citric acid cycle is a sequence of chemical events that remove high-energy electrons and utilize them in the electron transport chain to make ATP. The electron transport chain is a collection of proteins and chemical compounds. Electrons are transferred from one member of the transport chain to another by redox reactions. A redox reaction is the collection of oxidation and reduction reaction that involves the losing and gaining of elections, respectively.
Both the intermembranous space and the inner mitochondrial membrane are involved in the electron transport chain. The electrons move through a sequence of redox reactions to release energy. The majority of this energy is either wasted as heat or used to pump hydrogen ions (H+) from the mitochondrial matrix to the intermembranous space, resulting in a proton gradient, which is utilized in chemiosmosis by the protein ATP-synthase to produce a huge amount of ATP. The generation of ATP by the chemiosmosis process in mitochondrial membranes is called oxidative phosphorylation. The driving factor for ATP synthesis is a larger concentration of protons outside the inner membrane of the mitochondria than within the matrix. Substrate-level phosphorylation is a metabolic process that produces ATP by directly transferring a phosphate group from a substrate to ADP.
Chemiosmosis Diagram
The provided diagram shows the process of chemiosmosis and its components.
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Chemiosmosis Steps
Chemiosmosis is the process through which cells produce ATP for energy in the cellular respiration process. It generates energy in the same way as a water wheel generates power. ATP synthase functions similarly to a water wheel in the inner membrane of mitochondria, producing ATP by driving ADP and phosphate together.
- Electron carriers such as NADH and FADH provide electrons to the electron transport chain during chemiosmosis.
- The electrons create changes in the structures of the proteins, allowing H+ to pass through a selectively permeable cell membrane.
- Because of the positive charge of the hydrogen ions and their aggregation on one side of the membrane, the unequal distribution of hydrogen ions gradient across the membrane creates an electrochemical gradient
- After the gradient is generated, protons diffuse down the gradient via ATP synthase, a transport protein. Chemiosmosis refers to the movement of hydrogen ions across the membrane via ATP synthase.
- The flow of hydrogens catalyzes the pairing of phosphate with ADP, resulting in the formation of ATP.
So the role of chemiosmosis in the body is to generate about 90% of the ATP during cellular respiration. ATP is the energy currency of cells that has the main role in storing and transferring energy in the cells.
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Chemiosmosis Examples
Chemiosmosis generates ATP in mitochondria for cellular respiration and chloroplasts for photosynthesis, as well as in the majority of prokaryotes (bacteria and archaea).
Chemiosmosis in Chloroplasts
Plants capture solar energy from the sun in the form of energy-rich molecules in organelles known as chloroplasts. Chloroplasts are photosynthesis-related structures found in plant and green algal cells. The chemiosmosis reaction takes place in the matrix of the chloroplast known as the stroma which has a high amount of protons (hydrogen ions). Chemiosmosis is important in photosynthesis as proton gradient development across the semipermeable cell membrane of the chloroplast, which is coupled with the creation of ATP molecules.
One of the primary distinctions between chemiosmosis in mitochondria and chemiosmosis in chloroplasts is the source of energy. In mitochondria, high-energy electrons are produced from the breakdown of organic or food molecules (through redox reaction), whereas high-energy photons from light sources or the sun are the source in the case of the chloroplast. Cellular respiration converts food into ATP, whereas photosynthesis converts light energy into ATP.
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Chemiosmosis in Prokaryotic Cells
Chemiosmosis takes place in the cell membrane of prokaryotes because they lack mitochondria and chloroplasts as they lack membrane-bound organelles. Prokaryotes acquire energy from organic compound oxidation. The most commonly oxidized compounds are carbohydrates (particularly glucose), lipids, and protein. In prokaryotes such as bacteria, oxidation of these organic molecules leads to the creation of ATP as a chemical energy source. In bacteria, ATP synthase is fueled by the proton gradient formed by terminal oxidases to manufacture ATP. Terminal oxidases are respiratory chain enzymes that transport electrons from donors to final acceptors.
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Lesson Summary
Chemiosmosis is the movement of ions from high concentration to low concentration through a selectively permeable membrane. Chemiosmosis depends on the diffusion principle. Diffusion is the movement of particles from high concentration to low concentration; in other words, the movement of particles down their concentration gradient . A gradient means that the concentration of particles is greater on one side than on the other. Simple diffusion, facilitated diffusion, and osmosis are passive which means they don't require energy as substances move down their concentration gradient, unlike active transport which is the movement of substances from lower concentration to higher concentration and requires energy. A gradient of electrochemical potential, generally for an ion that may travel across a membrane, is referred to as an electrochemical gradient.
The chemiosmosis process is directly related to the synthesis of ATP during cellular respiration by the movement of hydrogen ions across a membrane. Hydrogen ions (protons) will diffuse from a high proton concentration area to a low proton concentration area. Cellular respiration takes place in subsequent three stages: glycolysis, Krebs cycle (citric acid cycle), and electron transport chain. . Redox reaction is the collection of oxidation and reduction reaction that involves the losing and gaining of elections, respectively. The electrons move through a sequence of redox reactions to release energy.
The generation of ATP by the chemiosmosis process in mitochondrial membranes is called oxidative phosphorylation. The driving factor for ATP synthesis is a larger concentration of protons outside the inner membrane of the mitochondria than within the matrix. Substrate-level phosphorylation is a metabolic process that produces ATP by directly transferring a phosphate group from a substrate to ADP. After the gradient is generated, protons diffuse down the gradient via ATP synthase, a transport protein. Chemiosmosis refers to the movement of hydrogen ions across the membrane via ATP synthase. Chemiosmosis is recognized in the photosynthesis process in chloroplast and also in the cell membrane of prokaryotic cells that lack chloroplasts and mitochondria.
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How Does Diffusion Happen in Cells?
There are some special examples of diffusion that occur inside cells. Cells have a plasma membrane, or outer barrier, that only lets certain things in or out. This allows substances to build up on one side of the membrane if there isn't a door to let them through. This creates what we call a gradient. A gradient is a situation in which there is more of a substance on one side than another. Energy can be stored in a gradient over the plasma membrane. If one substance is concentrated on one side of the membrane, it will want to diffuse until the concentrations are even.
Because this process occurs naturally, when it finally does happen, energy is released. The cell can harness this energy to do amazing things. Channel proteins allow substances to diffuse through the plasma membrane. Notice there are more of the blue circles outside the cell, so by diffusion they move into the cell.
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How Does Chemiosmosis Work?
Chemiosmosis is a special type of diffusion that happens over the plasma membrane. Chemiosmosis not only takes concentration into consideration, but also electrical charge. Thus, chemiosmosis exclusively has to do with the movement of ions (charged atoms) across the plasma membrane.
Diffusion not only works to equalize concentration on both sides of the membrane, but also to equalize charge. If there are more positive ions outside compared to inside the cell, positive ions will want to move down their electrical gradient into the cell. However, chemiosmosis also takes into consideration the concentration gradient. The molecule flows based on where there is more of its charge to where there is less and from a higher to lower concentration. The ion is flowing down its electrochemical gradient.
Chemiosmosis in the Body
All cells need energy, called ATP. Think of ATP as money. Each cell needs so much money to pay the bills every month, so just like people, they need to make money. The way the cell does this is through a process called cellular respiration, which starts with ingesting food and ends with making ATP.
So, how do we get from eating food all the way to ATP? Food travels from the digestive system to our cells. Then, cells use the energy stored in food molecules to pump hydrogen ions outside the cell. This creates an electrochemical gradient because there is a greater concentration of hydrogen ions outside the cell and a greater positive charge, because cells are naturally negative, and hydrogen ions have a positive charge.
The only way to let hydrogen back into the cell is through a protein called ATP synthase. The hydrogen ions flow through the protein, causing it to spin like a water mill. The wheel of the mill is the ATP synthase, and the water flowing down it is the hydrogen ions. The ATP synthase then harvests the energy stored in the electrochemical gradient to make ATP, just like the water mill takes the energy from the flowing water to make the wheel turn. The body is converting one kind of energy into another.
Think about the water wheel. The water pours down its concentration gradient, high to low, making the wheel spin. The energy from the water flowing is converted to energy to spin the wheel.
An analogous thing happens with ATP synthase. Hydrogen ions are the water, and ATP synthase is the wheel. So, ATP synthase is using the hydrogen ion gradient to convert ADP into ATP, which is the energy cells need. Without chemiosmosis, this wouldn't be possible. The body's cells couldn't get energy, and it wouldn't be possible to move around, breathe, or even think!
Lesson Summary
In summary, chemiosmosis is the process of a charged particle moving down its gradient based on the concentration and the charge of the ion. Chemiosmosis relies on the principle of diffusion, which says that everything always flows from where there is more to where there is less until an equilibrium, or balance, has been reached. Chemiosmosis involves both ions moving with their concentration gradient and their electrical gradient. An example of chemiosmosis in the cell is the hydrogen ion gradient used by ATP synthase to create cellular energy, or ATP. Hydrogen ions flow from outside the cell to inside, and the energy released is harnessed by ATP synthase to make ATP.
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Video Transcript
What Is Diffusion?
Chemiosmosis is the process of a molecule moving from high to low concentration, based on its charge and concentration inside a cell. This sounds pretty complicated. So, before talking about chemiosmosis, it will be important to understand a basic rule of the world: diffusion.
Diffusion is when anything moves from high concentration to low concentration. Think about food coloring in a jar of water. When the food coloring is first added to the water, it is concentrated in the center, but because there is less food coloring in other parts of the water, over time the food coloring spreads out or diffuses.
There are many more examples, such as delicious smells wafting from the kitchen during a holiday meal or warm air moving outwards from the house during the winter. The examples are so ubiquitous because diffusion is everywhere! Everything always moves from where there is more to where there is less. Check out the pictures of food coloring diffusing through a beaker of water.
|
How Does Diffusion Happen in Cells?
There are some special examples of diffusion that occur inside cells. Cells have a plasma membrane, or outer barrier, that only lets certain things in or out. This allows substances to build up on one side of the membrane if there isn't a door to let them through. This creates what we call a gradient. A gradient is a situation in which there is more of a substance on one side than another. Energy can be stored in a gradient over the plasma membrane. If one substance is concentrated on one side of the membrane, it will want to diffuse until the concentrations are even.
Because this process occurs naturally, when it finally does happen, energy is released. The cell can harness this energy to do amazing things. Channel proteins allow substances to diffuse through the plasma membrane. Notice there are more of the blue circles outside the cell, so by diffusion they move into the cell.
|
How Does Chemiosmosis Work?
Chemiosmosis is a special type of diffusion that happens over the plasma membrane. Chemiosmosis not only takes concentration into consideration, but also electrical charge. Thus, chemiosmosis exclusively has to do with the movement of ions (charged atoms) across the plasma membrane.
Diffusion not only works to equalize concentration on both sides of the membrane, but also to equalize charge. If there are more positive ions outside compared to inside the cell, positive ions will want to move down their electrical gradient into the cell. However, chemiosmosis also takes into consideration the concentration gradient. The molecule flows based on where there is more of its charge to where there is less and from a higher to lower concentration. The ion is flowing down its electrochemical gradient.
Chemiosmosis in the Body
All cells need energy, called ATP. Think of ATP as money. Each cell needs so much money to pay the bills every month, so just like people, they need to make money. The way the cell does this is through a process called cellular respiration, which starts with ingesting food and ends with making ATP.
So, how do we get from eating food all the way to ATP? Food travels from the digestive system to our cells. Then, cells use the energy stored in food molecules to pump hydrogen ions outside the cell. This creates an electrochemical gradient because there is a greater concentration of hydrogen ions outside the cell and a greater positive charge, because cells are naturally negative, and hydrogen ions have a positive charge.
The only way to let hydrogen back into the cell is through a protein called ATP synthase. The hydrogen ions flow through the protein, causing it to spin like a water mill. The wheel of the mill is the ATP synthase, and the water flowing down it is the hydrogen ions. The ATP synthase then harvests the energy stored in the electrochemical gradient to make ATP, just like the water mill takes the energy from the flowing water to make the wheel turn. The body is converting one kind of energy into another.
Think about the water wheel. The water pours down its concentration gradient, high to low, making the wheel spin. The energy from the water flowing is converted to energy to spin the wheel.
An analogous thing happens with ATP synthase. Hydrogen ions are the water, and ATP synthase is the wheel. So, ATP synthase is using the hydrogen ion gradient to convert ADP into ATP, which is the energy cells need. Without chemiosmosis, this wouldn't be possible. The body's cells couldn't get energy, and it wouldn't be possible to move around, breathe, or even think!
Lesson Summary
In summary, chemiosmosis is the process of a charged particle moving down its gradient based on the concentration and the charge of the ion. Chemiosmosis relies on the principle of diffusion, which says that everything always flows from where there is more to where there is less until an equilibrium, or balance, has been reached. Chemiosmosis involves both ions moving with their concentration gradient and their electrical gradient. An example of chemiosmosis in the cell is the hydrogen ion gradient used by ATP synthase to create cellular energy, or ATP. Hydrogen ions flow from outside the cell to inside, and the energy released is harnessed by ATP synthase to make ATP.
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Frequently Asked Questions
What is the role of chemiosmosis in photosynthesis?
The chemiosmosis reaction takes place in the matrix of the chloroplast known as the stroma which has a high amount of protons (hydrogen ions). Chemiosmosis is important in photosynthesis as proton gradient develops across the semipermeable cell membrane of the chloroplast, which is coupled with the creation of ATP molecules.
How does chemiosmosis produce ATP?
Chemiosmosis refers to the movement of hydrogen ions across the membrane via ATP synthase. When protons diffuse down the gradient via ATP synthase, the flow of hydrogen catalyzes the pairing of phosphate with ADP, resulting in the formation of ATP.
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