the removal of electrons and/or hydrogen atoms from a substrate is called what? This is a topic that many people are looking for. newyorkcityvoices.org is a channel providing useful information about learning, life, digital marketing and online courses …. it will help you have an overview and solid multi-faceted knowledge . Today, newyorkcityvoices.org would like to introduce to you Ch 25 Catabolism of a Glucose Molecule CC.mp4. Following along are instructions in the video below:
Of a glucose molecule most cells generate atp by breaking down carbohydrates especially glucose when when cells consume oxygen they can break down glucose into carbon dioxide and water and doing so they provide a typical body cell with 36 molecules of atp. The breakdown of glucose takes place in a series of small steps. The first steps begin in the cytosol of the cell here in the cytosol glucose is broken down into smaller molecules in a process.
Called glycolysis glycolysis does not require oxygen and. So the process is said to be anaerobic which. Means no oxygen the molecules produced through glycolysis are small enough to be absorbed by the mitochondria once these smaller molecules are in the mitochondria.
They will be involved in reactions. That use oxygen and are considered aerobic. The reactions inside the mitochondria will create most of the atp that the cell needs to function.
These reactions are collectively called aerobic metabolism or cellular. Respiration. Lets start with glycolysis glycolysis.
Is the breakdown of glucose to pyruvic acid in this process glucose. Which is a 6 carbon compound will break into two 3 carbon compounds of pyruvic acid pyruvic acid. Then loses a hydrogen atom to become pyruvate during the process of glycolysis cells.
Must use 2 atp molecules to complete this process. But will also create more atp through phosphorylation since glycolysis uses 2 atp. But creates.
4 atp. The net atp production during glycolysis is 2 atp for every glucose molecule catabolized this amount of atp is not enough for the cell to survive. But the pyruvate molecules hold much energy that will be used in the mitochondria to create more atp in addition to the atp that are produced the process of glycolysis will lose.
2. Hydrogen atoms. Which will be transferred to a hydrogen carrier called nad when the two hydrogen atoms are transferred to nad the molecule.
Then becomes nadh. The hydrogen will be carried to the electron transport system in the mitochondria. We will discuss later what happens to the hydrogen in the nadh molecule glycolysis is anaerobic because it does not require oxygen and it occurs in the cytosol of the cell.
If oxygen is present in the cell. The 3 carbon pyruvate molecules will enter the mitochondria and continue to be catabolized once in the mitochondria each pyruvate molecule will lost a carbon in a process called decarboxylation this carbon will join with oxygen to become carbon dioxide the carbon dioxide will diffuse out of the cell and into the bloodstream where it will be carried to lungs and be breathed out during expiration. The new molecule formed is now a 2 carbon molecule.
Called acetyl coenzyme. A acetyl coenzyme. A or acetyl coa will participate in reactions in the matrix of the mitochondria.
An enzyme called coenzyme a or coa will carry acetyl coa into the citric acid cycle in the matrix of the mitochondria recall that mitochondria are organelles with double membranes that is the mitochondria has two layers of membrane. The inner membrane and the outer membrane. The space in between the inner membrane and the outer membrane.
Is called the intermembrane space. The space inside the inner membrane. Is called the matrix.
The citric acid cycle will take place in the matrix of the mitochondria. The function of the citric acid cycle is to remove hydrogen atoms from organic molecules. And transfer them to coenzymes.
These. Coenzymes are nad and fad at the start of the citric acid cycle. Coa will release the 2 carbon acetyl coa.
So that it may be transferred to a 4 carbon. Molecule. Together.
These two molecules form a 6 carbon compound. Called citric acid. After releasing the acetyl coa.
The coa molecule is free to pick up another acetyl coa at the end of the citric acid cycle.
Two carbon atoms will have been removed to recreate the original 4 carbon compound these carbons join with oxygen atoms to form carbon dioxide. Which is a waste product of the cell and which will eventually diffuse out of the cell and into the blood and be transported to the lungs to be breathed out more importantly during the citric acid cycle. Hydrogen atoms will be tranferred to coenzyme nad and to another related one called fad nad and fad will be called nadh and fadh2 as they both pick up 2 hydrogen.
Atoms each nad is a negatively charged compound. And when it picks up. 2 hydrogen ions.
It becomes nadh h. However. It is commonly just referred to as nadh nadh and fadh2 will carry the hydrogen over to another area in the mitochondria to be used in the electron transport system nadh and fadh2 release their hydrogen to the cytochromes of the electron transport system.
Without the hydrogen nad and fad return to the citric acid cycle to pick up more hydrogen atoms the only immediate energy benefit of the citric acid cycle is that one gtp or guanosine. Triphosphate will be created from one gdp or guanosine diphosphate gtp is equivalent to atp because it will readily transfer a phosphate group to adp to create atp. So we can say that for each acetyl coa.
One atp is directly created by the citric acid cycle of course with one glucose molecule. Two acetyl coa are produced. So ultimately from one molecule of glucose.
The citric acid cycle. Produces. 2 atp.
The formation of gtp from gdp in the citric. Acid cycle. Is another example of substrate phosphorylation.
In this process. A phosphate group is transferred to a suitable acceptor molecule using energy from a chemical process this occurs in many reactions in the cytosol where a phosphate group is transferred to and adp to produce atp for example. The atp produced during glycolysis is generated through substrate phosphorylation normally.
However substrate phosphorylation. Only provides a small amount of atp and isnt enough for the cell to function. Most of the atp that cell needs will be produced during oxidative phosphorylation.
Which is what we will talk about next. Oxidative phosphorylation is the generation of atp within the mitochonria that requires both coenzymes and consumes oxygen. This process produces more than 90 of the atp used by body cells.
The key reactions take place in the electron transport system. Oxidative phosphorylation also forms water or h20 by combining two hydrogen atoms with one oxygen atom. The oxygen is provided from the atmosphere during respiration and hydrogen is found in all organic molecules.
So both hydrogen and oxygen are readily. Available for this reaction. The reaction of creating water releases a tremendous amount of energy.
There is so much energy released that this type of reaction is used to launch space shuttles into orbit obviously cells cant handle this much energy. So. The energy released must be gradual oxidative phosphorylation proceeds in a series of small controlled steps.
So that energy can be captured safely and atp can be generated in the process during these steps molecules lose electrons in a process called oxidation when one molecule loses an electron another molecule will gain it in a process called reduction. When electrons are passed from one molecule to another the electron donor is oxidized. And the electron recipient is reduced oxidation and reduction are important.
Because electrons carry chemical energy in a typical oxidation reduction reaction. The reduced molecule gains energy at the expense of the oxidized molecule. You can remember that molecules are oxidized when they lose electrons and they are reduced when they gain electrons by remembering the words oil rig or oxidation is loss and reduction is gain in an oxidation reduction exchange.
The reduced molecule does not gain. All the energy released by the oxidized molecule. Some energy is always released as heat.
The remaining energy will be used to form atp. The electron transport system starts with nadh and fadh2. Delivering hydrogen and atoms to cytochromes the cytochromes are integral and peripheral proteins that are embedded in the mitochondrial membrane.
These hydrogen atoms are from the citric acid cycle and were delivered by nad and fad in the form of nadh and fadh2 if you remember hydrogen atoms they consist of one electron and one proton.
The electron has a negative charge and the proton has a positive charge the electron carries energy with it nadh and fadh2 will both carry. 2 hydrogen atoms the electrons from these atoms will be passed from nadh and fadh2 to one of the cytochromes embedded in the inner membrane electrons will then be passed from one cytochrome to the next in small steps at the last cytochrome at the end of the electron transport system. An oxygen atom accepts the electron and will use its energy to combine the oxygen and hydrogen ions to form water note.
That this sequence begins with the removal of 2 hydrogen. Atoms from a substrate molecule. Nadh or fadh2 and ends with the formation of water by combining two hydrogen and one oxygen.
This reaction occurred in several steps had is occurredin. Only one step. It would have been highly explosive.
The coenzymes nadh and fadh2 transfer. The electrons to the first cytochrome in the electron transport system. And the electrons continue to be passed from one cytochrome to the next.
As they are passed along the electrons themselves release energy. This energy released causes. Hydrogen ion pumps to start working.
These pumps move hydrogen ions from the matrix across the inner membrane and into the intermembrane space. This causes a large concentration gradient for hydrogen ions between the matrix. And the intermembrane space.
Following the rules of diffusion hydrogen would diffuse from the high concentration in the innermembrane space to the lower concentration in the matrix hydrogen. Cant cross the inner membrane because they are not lipid soluble. However in the inner membrane.
An integral protein with a channel called atp synthase has the ability to permit hydrogen ions to diffuse into the matrix. This process is called chemiosmosis and it creates a kinetic energy. That will be used to convert adp to atp both adp and phosphate groups are already in the matrix of the mitochondria.
The energy from chemiosmosis will be used to phosphorylate adp. Which means a phosphate group will combine with adp to form atp because this process uses both coenzymes and oxygen the process of making atp through this method is called oxidative phosphorylation for every nadh molecule that transfers its molecules to the electron transport system. 3.
Atp will be formed for every fadh2 that transfers its hydrogen molecules to the electron transport system. 2. Atp will be formed at the end of glycolysis and cellular respiration.
The catabolism of one glucose molecule will yield 36 atp for the typical cell. Lets summarize where these atp come from from glycolysis. There are 2 atp that are directly made and there are there are 4 atp from the hydrogen that nad transports to the electron transport system in the citric acid cycle.
There are 2 atp that are directly made from the conversion of pyruvate to acetyl coa and from the citric acid cycle. There are 8 nadh that are transported to the electron transport system. These.
8. Nadh will help produce 24 atp. There are also 2 fadh2 from the citric acid cycle that are transported to the electron transport system.
And they will help to produce. 4 atp. So if we add these up 2 plus.
4 plus. 2. Plus.
24. Plus. 4.
Equals. 36. Thirty six is the number of atp that the catabolism of on molecule of glucose will generate thirty two of these are from oxidative phosphorylation.
Or aerobic metabolism and 2 of these are from anaerobic metabolism dont forget that carbon dioxide is produced in the citric acid cycle and water is produced in the electron transport system. .
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