3.6 Cellular Respiration
5 min read•december 28, 2022
Caroline Koffke
Haseung Jun
Caroline Koffke
Haseung Jun
is a chemical process with the following equation: + → H2O + CO2. All organisms, including those capable of photosynthesis, go through the process of . The overall reaction breaks down a carbohydrate, most frequently modeled by glucose, and converts the energy stored in that molecule into the most basic cellular energy, ATP. Respiration is almost the complete opposite of photosynthesis. So if you understood photosynthesis, understanding respiration should be relatively easy.
is broken down into three major steps which are dependent on one another: , the , and the . While takes place in the of the cell, the and the take place inside of the .
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Image courtesy of WikiMedia Commons.
Glycolysis
is the most evolutionarily conserved process in . The process takes place in all living organisms in almost the exact same way. Fundamentally, involves breaking down glucose, which possesses 6 carbons, into two 3-carbon molecules of .
In the process, a small amount of energy is released due to the breaking of bonds. This is captured as 2 molecules of ATP. Similarly, the breaking of bonds releases a few electrons that are picked up by electron carriers, . These electrons will be dropped off to the later.
Before can continue on into the to enter the , oxidation takes place. Oxidation is the loss of electrons. In this process, becomes a 2-carbon molecule called . A molecule of is released from each molecule that is oxidized.
Krebs Cycle
The takes place in the . In this cycle, similarly to the , a number of process a number of reactions that… you DON’T need to know about! (unless you go to medical school one day… good luck!)
Image courtesy of WikiMedia Commons.
The moral of the story is that a number of highly specific break down in reactions that create a number of electrons and a little bit of energy. The process results in the creation of a lot of electron carriers (around 8) such as and . These electron carriers will allow a lot of ATP production in the . 2 ATP are also produced in the .
Electron Transport Chain
The is where the majority of ATP is produced. The chain works in the same way as the in photosynthesis. A concentration gradient is formed, and is responsible for creating ATP.
When are dropped off by electron carriers to the , the hydrogen ion is pumped across the plasma membrane to form a high concentration gradient of . These will be used by .
The electron travels through the on a number of . It eventually ends up binding with oxygen, the final electron acceptor. When oxygen accepts the electron, it forms a bond with and water is created.
Image courtesy of WikiMedia Commons.
The concentration gradient of hydrogen travels through , in the same way as it does in photosynthesis, the kinetic energy is used to phosphorylate ADP into ATP. This process is called , as ions are moving down their concentration gradient. This process produces somewhere between 30 and 40 ATP molecules. Don’t worry, you don’t need to know specific numbers! Just know that a TON more ATP is produced through this process than through either or the .
Another important aspect of the is the recycling of electron carriers. This takes place when they drop off their electron and can then be refilled in or the . If these carriers were not emptied, the cycle would not be able to continue.
Fermentation
In organisms without access to oxygen, takes place. This happens in a number of bacteria, and in other organisms when oxygen is being used up faster than it can be inhaled (think crazy workout).
Without oxygen, the and cannot take place, because there is no final electron acceptor. Instead, electron carriers must be recycled elsewhere. This happens through the process of .
Organisms find other molecules to drop off their electrons. Some examples include creating , , and . This is how beer and wine are fermented by various bacteria and yeast. In humans, our body produces when oxygen is in short supply, such as in a tough workout. This can create sore muscles the next day.
Image courtesy of Pixabay.
The main takeaway about is that cells MUST recycle their electron carriers in order to continue to reuse them to produce ATP. They will find another molecule to drop their electrons off on. Secondly, during , , alone, is producing ATP. This means that ATP production is MUCH lower than in aerobic respiration.
Key Terms to Review (26)
Acetyl CoA
: Acetyl CoA (acetyl coenzyme A) is a molecule that participates in many biochemical reactions in protein, carbohydrate and lipid metabolism. Its main function is to deliver the acetyl group to the citric acid cycle (Krebs Cycle) to be oxidized for energy production.Anaerobic Respiration
: Anaerobic respiration is a type of respiration that does not use oxygen. It's a way for an organism to produce energy when oxygen levels are low.ATP (Adenosine Triphosphate)
: ATP is a high-energy molecule that stores and provides energy for many biochemical reactions in the cell.ATP synthase
: ATP synthase is an enzyme that creates the energy storage molecule adenosine triphosphate (ATP). It uses a proton gradient to power this process.C6H12O6
: C6H12O6 represents a molecule of glucose, which is a simple sugar that organisms use as an energy source.Calvin Cycle
: The Calvin Cycle is a set of chemical reactions that take place in chloroplasts during photosynthesis. It uses the energy from light to convert carbon dioxide into glucose.Carbon Dioxide
: Carbon dioxide (CO2) is a colorless, odorless gas produced by burning carbon and organic compounds and by respiration. It is naturally present in air (about 0.03 percent) and is absorbed by plants in photosynthesis.Cellular Respiration
: Cellular respiration is the process by which cells in plants, animals and fungi break down glucose (a type of sugar) and turn it into energy. This energy is then used to fuel various cellular activities.Chemiosmosis
: Chemiosmosis is the process by which ATP (adenosine triphosphate) is produced in the inner membrane of a mitochondrion. It involves the movement of ions across a selectively permeable membrane, down their electrochemical gradient.CO2 (Carbon Dioxide)
: Carbon dioxide is a colorless, odorless gas produced by burning carbon and organic compounds and by respiration. It's absorbed by plants in photosynthesis.Cytoplasm
: The cytoplasm is a jelly-like substance within a cell where all other cellular components are suspended and most cellular activities occur.Electron Transport Chain
: The electron transport chain is a series of protein complexes and electron carrier molecules within the inner mitochondrial membrane that harvest energy from electrons to create ATP.Electronegative Proteins
: Electronegative proteins are proteins that have a greater affinity for electrons. They play a key role in electron transport chains.Enzymes
: Enzymes are biological catalysts that speed up chemical reactions in living organisms without being consumed in the process.Ethanol
: Ethanol, also known as ethyl alcohol, is a type of alcohol produced by yeast during fermentation. It's found in alcoholic beverages and used as a biofuel.FADH2
: FADH2 (Flavin Adenine Dinucleotide) is a high-energy molecule that stores energy for later use during cellular respiration, specifically in the electron transport chain.Fermentation
: Fermentation is an anaerobic process (meaning it doesn't require oxygen) used by many cells to produce ATP from glucose when oxygen levels are low or absent.Glycolysis
: Glycolysis is a metabolic pathway that converts glucose into pyruvate with the simultaneous production of small amounts of ATP (energy).H2O (Water)
: H2O, or water, is a molecule composed of two hydrogen atoms bonded to one oxygen atom. It's essential for all known forms of life and plays a critical role in various biological processes.Hydrogen Ions
: Hydrogen ions (H+) are single proton with no electrons and play crucial roles in chemical reactions, especially those involving acids and bases.Krebs Cycle
: The Krebs Cycle, also known as the citric acid cycle, is a series of chemical reactions used by all aerobic organisms to generate energy through the oxidation of acetyl-CoA derived from carbohydrates, fats and proteins into ATP.Lactic Acid
: Lactic acid is a byproduct of anaerobic respiration, particularly in muscle cells when oxygen levels are low. It's what causes the burning sensation during intense exercise.Mitochondria
: Mitochondria are organelles within eukaryotic cells that produce most of the cell’s supply of adenosine triphosphate (ATP), used as a source of chemical energy.NADH
: NADH is a coenzyme that functions as a reducing agent. It carries electrons from one reaction to another.O2
: O2 or Oxygen gas is a colorless, odorless reactive gas that forms about 21% of the earth's atmosphere. It supports combustion and respiration in most living organisms.Pyruvate
: Pyruvate is a three-carbon compound that forms as an end product of glycolysis. It's the key junction in cellular metabolism, since it can either be used to generate energy via the citric acid cycle or converted into various other molecules.3.6 Cellular Respiration
5 min read•december 28, 2022
Caroline Koffke
Haseung Jun
Caroline Koffke
Haseung Jun
is a chemical process with the following equation: + → H2O + CO2. All organisms, including those capable of photosynthesis, go through the process of . The overall reaction breaks down a carbohydrate, most frequently modeled by glucose, and converts the energy stored in that molecule into the most basic cellular energy, ATP. Respiration is almost the complete opposite of photosynthesis. So if you understood photosynthesis, understanding respiration should be relatively easy.
is broken down into three major steps which are dependent on one another: , the , and the . While takes place in the of the cell, the and the take place inside of the .
Image courtesy of WikiMedia Commons.
Glycolysis
is the most evolutionarily conserved process in . The process takes place in all living organisms in almost the exact same way. Fundamentally, involves breaking down glucose, which possesses 6 carbons, into two 3-carbon molecules of .
In the process, a small amount of energy is released due to the breaking of bonds. This is captured as 2 molecules of ATP. Similarly, the breaking of bonds releases a few electrons that are picked up by electron carriers, . These electrons will be dropped off to the later.
Before can continue on into the to enter the , oxidation takes place. Oxidation is the loss of electrons. In this process, becomes a 2-carbon molecule called . A molecule of is released from each molecule that is oxidized.
Krebs Cycle
The takes place in the . In this cycle, similarly to the , a number of process a number of reactions that… you DON’T need to know about! (unless you go to medical school one day… good luck!)
Image courtesy of WikiMedia Commons.
The moral of the story is that a number of highly specific break down in reactions that create a number of electrons and a little bit of energy. The process results in the creation of a lot of electron carriers (around 8) such as and . These electron carriers will allow a lot of ATP production in the . 2 ATP are also produced in the .
Electron Transport Chain
The is where the majority of ATP is produced. The chain works in the same way as the in photosynthesis. A concentration gradient is formed, and is responsible for creating ATP.
When are dropped off by electron carriers to the , the hydrogen ion is pumped across the plasma membrane to form a high concentration gradient of . These will be used by .
The electron travels through the on a number of . It eventually ends up binding with oxygen, the final electron acceptor. When oxygen accepts the electron, it forms a bond with and water is created.
Image courtesy of WikiMedia Commons.
The concentration gradient of hydrogen travels through , in the same way as it does in photosynthesis, the kinetic energy is used to phosphorylate ADP into ATP. This process is called , as ions are moving down their concentration gradient. This process produces somewhere between 30 and 40 ATP molecules. Don’t worry, you don’t need to know specific numbers! Just know that a TON more ATP is produced through this process than through either or the .
Another important aspect of the is the recycling of electron carriers. This takes place when they drop off their electron and can then be refilled in or the . If these carriers were not emptied, the cycle would not be able to continue.
Fermentation
In organisms without access to oxygen, takes place. This happens in a number of bacteria, and in other organisms when oxygen is being used up faster than it can be inhaled (think crazy workout).
Without oxygen, the and cannot take place, because there is no final electron acceptor. Instead, electron carriers must be recycled elsewhere. This happens through the process of .
Organisms find other molecules to drop off their electrons. Some examples include creating , , and . This is how beer and wine are fermented by various bacteria and yeast. In humans, our body produces when oxygen is in short supply, such as in a tough workout. This can create sore muscles the next day.
Image courtesy of Pixabay.
The main takeaway about is that cells MUST recycle their electron carriers in order to continue to reuse them to produce ATP. They will find another molecule to drop their electrons off on. Secondly, during , , alone, is producing ATP. This means that ATP production is MUCH lower than in aerobic respiration.
Key Terms to Review (26)
Acetyl CoA
: Acetyl CoA (acetyl coenzyme A) is a molecule that participates in many biochemical reactions in protein, carbohydrate and lipid metabolism. Its main function is to deliver the acetyl group to the citric acid cycle (Krebs Cycle) to be oxidized for energy production.Anaerobic Respiration
: Anaerobic respiration is a type of respiration that does not use oxygen. It's a way for an organism to produce energy when oxygen levels are low.ATP (Adenosine Triphosphate)
: ATP is a high-energy molecule that stores and provides energy for many biochemical reactions in the cell.ATP synthase
: ATP synthase is an enzyme that creates the energy storage molecule adenosine triphosphate (ATP). It uses a proton gradient to power this process.C6H12O6
: C6H12O6 represents a molecule of glucose, which is a simple sugar that organisms use as an energy source.Calvin Cycle
: The Calvin Cycle is a set of chemical reactions that take place in chloroplasts during photosynthesis. It uses the energy from light to convert carbon dioxide into glucose.Carbon Dioxide
: Carbon dioxide (CO2) is a colorless, odorless gas produced by burning carbon and organic compounds and by respiration. It is naturally present in air (about 0.03 percent) and is absorbed by plants in photosynthesis.Cellular Respiration
: Cellular respiration is the process by which cells in plants, animals and fungi break down glucose (a type of sugar) and turn it into energy. This energy is then used to fuel various cellular activities.Chemiosmosis
: Chemiosmosis is the process by which ATP (adenosine triphosphate) is produced in the inner membrane of a mitochondrion. It involves the movement of ions across a selectively permeable membrane, down their electrochemical gradient.CO2 (Carbon Dioxide)
: Carbon dioxide is a colorless, odorless gas produced by burning carbon and organic compounds and by respiration. It's absorbed by plants in photosynthesis.Cytoplasm
: The cytoplasm is a jelly-like substance within a cell where all other cellular components are suspended and most cellular activities occur.Electron Transport Chain
: The electron transport chain is a series of protein complexes and electron carrier molecules within the inner mitochondrial membrane that harvest energy from electrons to create ATP.Electronegative Proteins
: Electronegative proteins are proteins that have a greater affinity for electrons. They play a key role in electron transport chains.Enzymes
: Enzymes are biological catalysts that speed up chemical reactions in living organisms without being consumed in the process.Ethanol
: Ethanol, also known as ethyl alcohol, is a type of alcohol produced by yeast during fermentation. It's found in alcoholic beverages and used as a biofuel.FADH2
: FADH2 (Flavin Adenine Dinucleotide) is a high-energy molecule that stores energy for later use during cellular respiration, specifically in the electron transport chain.Fermentation
: Fermentation is an anaerobic process (meaning it doesn't require oxygen) used by many cells to produce ATP from glucose when oxygen levels are low or absent.Glycolysis
: Glycolysis is a metabolic pathway that converts glucose into pyruvate with the simultaneous production of small amounts of ATP (energy).H2O (Water)
: H2O, or water, is a molecule composed of two hydrogen atoms bonded to one oxygen atom. It's essential for all known forms of life and plays a critical role in various biological processes.Hydrogen Ions
: Hydrogen ions (H+) are single proton with no electrons and play crucial roles in chemical reactions, especially those involving acids and bases.Krebs Cycle
: The Krebs Cycle, also known as the citric acid cycle, is a series of chemical reactions used by all aerobic organisms to generate energy through the oxidation of acetyl-CoA derived from carbohydrates, fats and proteins into ATP.Lactic Acid
: Lactic acid is a byproduct of anaerobic respiration, particularly in muscle cells when oxygen levels are low. It's what causes the burning sensation during intense exercise.Mitochondria
: Mitochondria are organelles within eukaryotic cells that produce most of the cell’s supply of adenosine triphosphate (ATP), used as a source of chemical energy.NADH
: NADH is a coenzyme that functions as a reducing agent. It carries electrons from one reaction to another.O2
: O2 or Oxygen gas is a colorless, odorless reactive gas that forms about 21% of the earth's atmosphere. It supports combustion and respiration in most living organisms.Pyruvate
: Pyruvate is a three-carbon compound that forms as an end product of glycolysis. It's the key junction in cellular metabolism, since it can either be used to generate energy via the citric acid cycle or converted into various other molecules.
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