oxidate the glucose into a 3C atom containing pyruvate<\/p>\n\n\n\n
3 major phases:<\/p>\n\n\n\n
I. Phosphorylation (glucose into glucose-6-P) key enzymes: hexokinase\/glucokinase<\/p>\n\n\n\n
II. Splitting the 6 atoms into 3C Glycerin-aldehyde-P + dihydroxy-acetone-P 3C key enzyme: aldolase<\/p>\n\n\n\n
III. Oxidoreduction and phosphorylation <\/div><\/p>\n\n\n\n
- During glycolysis, two pyruvates will be made from 1 glucose molecule<\/li>
- Each human cell is capable of this transformation, and each cell can continue to produce energy using its mitochondria<\/li><\/ul>\n\n\n\n
Our body demands approximately 160 grams of glucose per day, from which the brain consumes 120 grams, and the remaining 40 grams are used by other tissues such as red blood cells, leukocytes, cornea, and kidneys, as they can only gain energy from glucose. <\/p>\n\n\n\n
Glycolysis<\/h4>\n<\/span>\n\n\n
If we take a simple look at the process more about reducing the number of the carbons from C6 into C3 in the form of pyruvate. The whole process requires ATP and a lot of enzymatic reactions.<\/p>\n\n\n\n
We can divide into three significant phases:<\/p>\n\n\n\n
- Initiation and phosphorylation<\/strong> (marking the central glucose for maintaining with a phosphate group)<\/li>
- Splitting<\/strong> (make a decision in which direction going further; generation C3-C3 units)<\/li>
- Oxidoreduction and phosphorylation<\/strong> (playing with phosphate groups to finally reached the C3 pyruvate)<\/li><\/ol>\n\n\n\n
![\"\"](\"https:\/\/meddists.com\/learn\/wp-content\/uploads\/2021\/09\/GLYCOLYSIS-1-934x1024.png\")
<\/a>Figure 1. Glycolysis<\/strong><\/figcaption><\/figure><\/div>\n\n\n<\/span>\n I. Initiation and phosphorylation<\/h4>\n<\/span>\n\n\n
1. Glycolysis takes place in the cytosol.
The first step is by phosphorylation<\/strong> (by investing in ATP) hexokinase<\/strong> or glucokinase<\/strong> (liver-specific) so that the negatively charged molecule does not leave the cell \u2014 glucose-6-phosphate and ADP is produced.<\/p>\n\n\n\nThere is an essential difference between the two enzymes since hexokinase is non-specific<\/strong> to glucose, most of our cells have it.
Glucokinase <\/strong>is specific for the liver, it is active only when the sugar level is extremely high in the bloodstream, thus the liver’s uptake induces the phosphorylation of it.<\/p>\n\n\n\nPhosphorylation reaction is irreversible <\/strong>(Figure 1). <\/p>\n\n\n\n
2-3. Glucose 6-phosphate is converted to fructose 6-phosphate by the enzyme phosphoglucose isomerase<\/strong>, followed by further irreversible phosphorylation by phosphofructokinase I<\/strong> and ATP, with the final result being fructose-1,6-bisphosphate.<\/p>\n\n\n\n
This step’s main activator is the fructose-2,6-bisphosphate<\/strong> created by phosphofructokinase II<\/strong>. As it is being activated by AMP<\/strong>, it is also inhibited by ATP, citrate<\/strong> and fatty acid<\/strong>s.<\/p>\n\n\n<\/span>\n
II. Splitting phase<\/h2>\n<\/span>\n\n\n
4. Fructose-1,6-bisphosphate is split into two tri-phosphate, one aldose<\/strong> (glyceraldehyde-3-phosphate) and a ketose<\/strong> (dihydroxyacetone phosphate); the reaction is reversible and catalyzes aldolase. The two products may even overlap with the operation of the triosephosphate isomerase (Figure 2<\/strong>).<\/p>\n\n\n\n
![\"\"](\"https:\/\/meddists.com\/learn\/wp-content\/uploads\/2021\/09\/GLYCOLYSIS1-1024x318.png\")
<\/a>Figure 2. Aldolase reaction in the splitting phase<\/strong><\/figcaption><\/figure>\n\n\n<\/span>\n III. Oxidoreduction and phosphorylation<\/strong><\/h2>\n<\/span>\n\n\n
![\"\"](\"https:\/\/meddists.com\/learn\/wp-content\/uploads\/2021\/10\/GLYCOLYSIS2-956x1024.png\")
<\/a>Figure 3. Oxidoreduction and phosphorylation steps of glycolysis<\/strong><\/figcaption><\/figure><\/div>\n\n\n\n 5. During glycolysis, glyceraldehyde-3-phosphate is oxidised and phosphorylated reversibly by D-glyceraldehyde-3-phosphate dehydrogenase<\/strong>, which is an SH enzyme with cysteine in its active centre.<\/p>\n\n\n\n
6. The aldehyde is converted into a carboxyl group, reducing NAD+<\/sup>. This is followed by phosphorylation, 1,3-bisphosphoglycerate containing phosphate 1, anhydride, and phosphate is a thioester bond.<\/p>\n\n\n\n
7. From this, phosphate is transferred by phosphoglycerate kinase<\/strong> to ADP, resulting in ATP and 3-phosphoglycerate. Substrate phosphorylation and reversible (Figure 4<\/strong>)<\/p>\n\n\n\n
8. Phosphoglycerate mutase reaction produces 2-phosphoglycerate from 3-phosphoglycerate converted by enolase<\/strong> to phosphoenolpyruvate (PEP). Both are reversible. If this reacts faster with 1,3-bisphosphoglycerate than kinase, then 2,3-BPG is produced, which is essential for delivering haemoglobin oxygen (2,3 BGP-shunt reaction<\/strong>).<\/p>\n\n\n\n
9. Pyruvate kinase<\/strong> takes the phosphate of phosphoenolpyruvate in high potential binding to ADP, pyruvate and ATP are formed.<\/p>\n\n\n<\/span>\n
2,3-BPG shunt reaction<\/h2>\n<\/span>\n\n\n
The 2,3-bisphosphoglycerate (2,3 BPG)<\/strong> shunt is important in red blood cells. The 2,3-BPG decreases the oxygen affinity of haemoglobin. This compound, in a catalytic amount, is also required for phosphoglycerate mutase reaction.<\/p>\n\n\n\n
In anaerobic circumstances<\/strong>, the 2,3-DPG binds to a specific site in the \u03b2-chain of Hb and it decreases its oxygen affinity by shifting the balance of the so-called T and R conformations of the molecule. In normal cases, the production of the 2,3-BPG is 5-15% from the total glycolysis reaction in RBCs. Less oxygen generates more (Figure 4).<\/p>\n\n\n\n
![\"\"](\"https:\/\/meddists.com\/learn\/wp-content\/uploads\/2021\/10\/GLYCOLYSIS3-1024x319.png\")
<\/a>Figure 4. 2,3 BPG shunt reaction in RBCs<\/strong><\/figcaption><\/figure>\n\n\n\n Pyruvate can be used in several pathways: it can be converted into acetyl-CoA under aerobic conditions and enter the citrate cycle, while anaerobic conditions convert lactate dehydrogenase into reversible lactate by NADH.<\/em><\/p>\n\n\n<\/span>\n
Lactate production<\/strong><\/h2>\n<\/span>\n\n\n
During glycolysis, NAD+<\/sup> and oxygen are continuously required. If the level of oxygen drops, an anaerobic condition is developed. That induces an alternative process when the pyruvate is changing into lactate in a reversible way (Figure 5). Lactate dehydrogenase (LDH) has five isoforms working on the same reaction but in a different types of tissues.<\/p>\n\n\n\n
- Splitting<\/strong> (make a decision in which direction going further; generation C3-C3 units)<\/li>
- Initiation and phosphorylation<\/strong> (marking the central glucose for maintaining with a phosphate group)<\/li>
![\"\"](\"https:\/\/meddists.com\/learn\/wp-content\/uploads\/2021\/09\/GLYCOLYSIS-1.png\")
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