Glycolysis is the metabolic process that serves as the foundation for both aerobic and anaerobic cellular respiration. In glycolysis, glucose is converted into pyruvate. Glucose is a six- memebered ring molecule found in the blood and is usually a result of the breakdown of carbohydrates into sugars. It enters cells through specific transporter proteins that move it from outside the cell into the cell’s cytosol. All of the glycolytic enzymes are found in the cytosol.
糖酵解是一种代谢过程，是有氧和无氧细胞呼吸的基础。在糖酵解中，葡萄糖转化为丙酮酸。葡萄糖是血液中发现的六元环分子，通常是碳水化合物分解成糖的结果。它通过特定的转运蛋白进入细胞，将其从细胞外转移到细胞质中。所有糖酵解酶都存在于细胞质中。

The overall reaction of glycolysis which occurs in the cytoplasm is represented simply as:
细胞质中发生的糖酵解的总体反应简单地表示为：

C6H12O6 + 2 NAD+ + 2 ADP + 2 P —–> 2 pyruvic acid, (CH3(C=O)COOH + 2 ATP + 2 NADH + 2 H⁺
C 6 H 12 O 6 + 2 NAD + + 2 ADP + 2 P —–> 2 丙酮酸，(CH < b4> (C=O)COOH + 2 ATP + 2 NADH + 2 H +

Step 1: Hexokinase 第 1 步：己糖激酶

The first step in glycolysis is the conversion of D-glucose into glucose-6-phosphate. The enzyme that catalyzes this reaction is hexokinase.
糖酵解的第一步是将 D-葡萄糖转化为葡萄糖-6-磷酸。催化该反应的酶是己糖激酶。

Details: 细节：

Here, the glucose ring is phosphorylated. Phosphorylation is the process of adding a phosphate group to a molecule derived from ATP. As a result, at this point in glycolysis, 1 molecule of ATP has been consumed.
此处，葡萄糖环被磷酸化。磷酸化是在 ATP 衍生的分子上添加磷酸基团的过程。结果，在糖酵解的此时，1 分子 ATP 已被消耗。

The reaction occurs with the help of the enzyme hexokinase, an enzyme that catalyzes the phosphorylation of many six-membered glucose-like ring structures. Atomic magnesium (Mg) is also involved to help shield the negative charges from the phosphate groups on the ATP molecule. The result of this phosphorylation is a molecule called glucose-6-phosphate (G6P), thusly called because the 6′ carbon of the glucose acquires the phosphate group.
该反应在己糖激酶的帮助下发生，己糖激酶是一种催化许多六元葡萄糖样环结构磷酸化的酶。原子镁 (Mg) 还有助于屏蔽 ATP 分子上磷酸基团的负电荷。这种磷酸化的结果是一种称为葡萄糖-6-磷酸 (G6P) 的分子，之所以如此命名是因为葡萄糖的 6’ 碳获得了磷酸基团。

Step 2: Phosphoglucose Isomerase

第 2 步：磷酸葡萄糖异构酶

The second reaction of glycolysis is the rearrangement of glucose 6-phosphate (G6P) into fructose 6-phosphate (F6P) by glucose phosphate isomerase (Phosphoglucose Isomerase).
糖酵解的第二个反应是葡萄糖磷酸异构酶（Phosphoglucose Isomerase）将葡萄糖6-磷酸（G6P）重排成果糖6-磷酸（F6P）。

Details: 细节：

The second step of glycolysis involves the conversion of glucose-6-phosphate to fructose-6-phosphate (F6P). This reaction occurs with the help of the enzyme phosphoglucose isomerase (PI). As the name of the enzyme suggests, this reaction involves an isomerization reaction.
糖酵解的第二步涉及将葡萄糖-6-磷酸转化为果糖-6-磷酸（F6P）。该反应在磷酸葡萄糖异构酶 (PI) 的帮助下发生。正如酶的名称所示，该反应涉及异构化反应。

The reaction involves the rearrangement of the carbon-oxygen bond to transform the six-membered ring into a five-membered ring. To rearrangement takes place when the six-membered ring opens and then closes in such a way that the first carbon becomes now external to the ring.
该反应涉及碳-氧键的重排，将六元环转变为五元环。当六元环打开然后关闭时，就会发生重排，使得第一个碳现在位于环的外部。

Step 3: Phosphofructokinase

第三步：磷酸果糖激酶

Phosphofructokinase, with magnesium as a cofactor, changes fructose 6-phosphate into fructose 1,6-bisphosphate.
磷酸果糖激酶以镁作为辅助因子，将果糖 6-磷酸转变为果糖 1,6-二磷酸。

Details: 细节：

In the third step of glycolysis, fructose-6-phosphate is converted to fructose- 1,6-_bi_sphosphate (FBP). Similar to the reaction that occurs in step 1 of glycolysis, a second molecule of ATP provides the phosphate group that is added on to the F6P molecule.
在糖酵解的第三步中，6-磷酸果糖转化为 1,6-二磷酸果糖 (FBP)。与糖酵解步骤 1 中发生的反应类似，第二个 ATP 分子提供添加到 F6P 分子上的磷酸基团。

The enzyme that catalyzes this reaction is phosphofructokinase (PFK). As in step 1, a magnesium atom is involved to help shield negative charges.
催化该反应的酶是磷酸果糖激酶（PFK）。与步骤 1 一样，镁原子有助于屏蔽负电荷。

Step 4: Aldolase 第四步：醛缩酶

The enzyme Aldolase splits fructose 1, 6-bisphosphate into two sugars that are isomers of each other. These two sugars are dihydroxyacetone phosphate  (DHAP) and glyceraldehyde 3-phosphate (GAP).
醛缩酶将果糖 1, 6-二磷酸分解成两种互为异构体的糖。这两种糖是磷酸二羟丙酮 (DHAP) 和 3-磷酸甘油醛 (GAP)。

• DHAP: converted to glycerol-3 phosphate during the synthesis of triglycerides, in fed state.
• GAP: continue in glycolysis

Details: 细节：

This step utilizes the enzyme aldolase, which catalyzes the cleavage of FBP to yield two 3-carbon molecules. One of these molecules is called glyceraldehyde-3-phosphate (GAP) and the other is called dihydroxyacetone phosphate (DHAP).
此步骤利用醛缩酶，该酶催化 FBP 裂解，产生两个 3 碳分子。其中一种分子称为 3-磷酸甘油醛 (GAP)，另一种分子称为磷酸二羟基丙酮 (DHAP)。

Step 5: Triosephosphate isomerase

步骤5：磷酸三糖异构酶

The enzyme triosephosphate isomerase rapidly inter- converts the molecules dihydroxyacetone phosphate (DHAP) and glyceraldehyde 3-phosphate (GAP). Glyceraldehyde phosphate is removed / used in next step of Glycolysis.
磷酸三糖异构酶可快速将磷酸二羟丙酮 (DHAP) 分子和 3-磷酸甘油醛 (GAP) 分子相互转化。磷酸甘油醛在糖酵解的下一步中被去除/使用。

Details: 细节：

GAP is the only molecule that continues in the glycolytic pathway. As a result, all of the DHAP molecules produced are further acted on by the enzyme Triosephosphate isomerase (TIM), which reorganizes the DHAP into GAP so it can continue in glycolysis. At this point in the glycolytic pathway, we have two 3-carbon molecules, but have not yet fully converted glucose into pyruvate.
GAP 是唯一在糖酵解途径中持续存在的分子。结果，产生的所有 DHAP 分子进一步受到磷酸丙糖异构酶 (TIM) 的作用，将 DHAP 重组为 GAP，以便它可以继续进行糖酵解。此时，在糖酵解途径中，我们有两个 3 碳分子，但尚未完全将葡萄糖转化为丙酮酸。

Step 6: Glyceraldehyde-3-phosphate Dehydrogenase

步骤6：3-磷酸甘油醛脱氢酶

Glyceraldehyde-3-phosphate dehydrogenase (GAPDH) dehydrogenates and adds an inorganic phosphate to glyceraldehyde 3-phosphate, producing 1,3-bisphosphoglycerate.
3-磷酸​​甘油醛脱氢酶 (GAPDH) 脱氢并向 3-磷酸甘油醛添加无机磷酸盐，生成 1,3-二磷酸甘油酸酯。

Details: 细节：

In this step, two main events take place: 1) glyceraldehyde-3-phosphate is oxidized by the coenzyme nicotinamide adenine dinucleotide (NAD); 2) the molecule is phosphorylated by the addition of a free phosphate group. The enzyme that catalyzes this reaction is glyceraldehyde-3-phosphate dehydrogenase (GAPDH).
在此步骤中，发生两个主要事件：1）3-磷酸甘油醛被辅酶烟酰胺腺嘌呤二核苷酸（NAD）氧化； 2) 通过添加游离磷酸基团使分子磷酸化。催化该反应的酶是3-磷酸甘油醛脱氢酶(GAPDH)。

The enzyme GAPDH contains appropriate structures and holds the molecule in a conformation such that it allows the NAD molecule to pull a hydrogen off the GAP, converting the NAD to NADH. The phosphate group then attacks the GAP molecule and releases it from the enzyme to yield 1,3 bisphoglycerate, NADH, and a hydrogen atom.
酶 GAPDH 含有适当的结构，并使分子保持某种构象，从而允许 NAD 分子从 GAP 上拉出一个氢，将 NAD 转化为 NADH。然后磷酸基团攻击 GAP 分子并将其从酶中释放出来，产生 1,3 双磷酸甘油酸、NADH 和一个氢原子。

Step 7: Phosphoglycerate Kinase

第7步：磷酸甘油酸激酶

Phosphoglycerate kinase transfers a phosphate group from 1,3-bisphosphoglycerate to ADP to form ATP and 3-phosphoglycerate.
磷酸甘油酸激酶将磷酸基团从 1,3-二磷酸甘油酸转移至 ADP，形成 ATP 和 3-磷酸甘油酸。

Details: 细节：

In this step, 1,3 bisphoglycerate is converted to 3-phosphoglycerate by the enzyme phosphoglycerate kinase (PGK). This reaction involves the loss of a phosphate group from the starting material. The phosphate is transferred to a molecule of ADP that yields our first molecule of ATP. Since we actually have two molecules of 1,3 bisphoglycerate (because there were two 3-carbon products from stage 1 of glycolysis), we actually synthesize two molecules of ATP at this step. With this synthesis of ATP, we have cancelled the first two molecules of ATP that we used, leaving us with a net of 0 ATP molecules up to this stage of glycolysis.
在此步骤中，1,3 双磷酸甘油酸通过磷酸甘油酸激酶 (PGK) 转化为 3-磷酸甘油酸。该反应涉及起始材料中磷酸基团的损失。磷酸盐被转移到 ADP 分子中，产生我们的第一个 ATP 分子。由于我们实际上有两个 1,3 双磷酸甘油酸分子（因为糖酵解第一阶段有两个 3-碳产物），因此我们实际上在这一步合成了两个 ATP 分子。通过这种 ATP 的合成，我们取消了使用的前两个 ATP 分子，在糖酵解的这一阶段留下了 0 个 ATP 分子。

Again, we see that an atom of magnesium is involved to shield the negative charges on the phosphate groups of the ATP molecule.
我们再次看到镁原子参与屏蔽 ATP 分子磷酸基团上的负电荷。

Step 8: Phosphoglycerate Mutase

第8步：磷酸甘油酸变位酶

The enzyme phosphoglycero mutase relocates the P from 3- phosphoglycerate from the 3rd carbon to the 2nd carbon to form 2-phosphoglycerate.
磷酸甘油变位酶将 3-磷酸甘油酸中的 P 从第 3 个碳重新定位到第 2 个碳，形成 2-磷酸甘油酸。

Details: 细节：

This step involves a simple rearrangement of the position of the phosphate group on the 3 phosphoglycerate molecule, making it 2 phosphoglycerate. The molecule responsible for catalyzing this reaction is called phosphoglycerate mutase (PGM). A mutase is an enzyme that catalyzes the transfer of a functional group from one position on a molecule to another.
此步骤涉及 3 磷酸甘油酸分子上磷酸基团位置的简单重排，使其成为 2 磷酸甘油酸。负责催化该反应的分子称为磷酸甘油酸变位酶（PGM）。变位酶是一种催化官能团从分子上的一个位置转移到另一个位置的酶。

The reaction mechanism proceeds by first adding an additional phosphate group to the 2′ position of the 3 phosphoglycerate. The enzyme then removes the phosphate from the 3′ position leaving just the 2′ phosphate, and thus yielding 2 phsophoglycerate. In this way, the enzyme is also restored to its original, phosphorylated state.
该反应机理首先在 3 磷酸甘油酸酯的 2’ 位上添加一个额外的磷酸基团。然后，酶从 3’ 位置去除磷酸盐，仅留下 2’ 磷酸盐，从而产生 2 磷酸甘油酸。通过这种方式，酶也恢复到其原始的磷酸化状态。

Step 9: Enolase 第9步：烯醇化酶

The enzyme enolase removes a molecule of water from 2-phosphoglycerate to form phosphoenolpyruvic acid (PEP).
烯醇酶从 2-磷酸甘油酸中除去一个水分子，形成磷酸烯醇丙酮酸 (PEP)。

Details: 细节：

This step involves the conversion of 2 phosphoglycerate to phosphoenolpyruvate (PEP). The reaction is catalyzed by the enzyme enolase. Enolase works by removing a water group, or dehydrating the 2 phosphoglycerate. The specificity of the enzyme pocket allows for the reaction to occur through a series of steps too complicated to cover here.
此步骤涉及将 2 磷酸甘油酸转化为磷酸烯醇丙酮酸 (PEP)。该反应由烯醇酶催化。烯醇化酶的作用是去除水基团，或使 2 磷酸甘油酸脱水。酶袋的特异性允许反应通过一系列过于复杂的步骤发生，此处无法介绍。

Step 10: Pyruvate Kinase 第10步：丙酮酸激酶

The enzyme pyruvate kinase transfers a P from phosphoenolpyruvate (PEP) to ADP to form pyruvic acid and ATP Result in step 10.
丙酮酸激酶将 P 从磷酸烯醇丙酮酸 (PEP) 转移到 ADP，形成丙酮酸和 ATP 结果如步骤 10 所示。

Details: 细节：

The final step of glycolysis converts phosphoenolpyruvate into pyruvate with the help of the enzyme pyruvate kinase. As the enzyme’s name suggests, this reaction involves the transfer of a phosphate group. The phosphate group attached to the 2′ carbon of the PEP is transferred to a molecule of ADP, yielding ATP. Again, since there are two molecules of PEP, here we actually generate 2 ATP molecules.
糖酵解的最后一步在丙酮酸激酶的帮助下将磷酸烯醇丙酮酸转化为丙酮酸。正如该酶的名称所示，该反应涉及磷酸基团的转移。连接到 PEP 2’ 碳的磷酸基团被转移到 ADP 分子上，产生 ATP。同样，由于有两个 PEP 分子，这里我们实际上生成了 2 个 ATP 分子。

Steps 1 and 3 = – 2ATP
步骤 1 和 3 = – 2ATP
Steps 7 and 10 = + 4 ATP
步骤 7 和 10 = + 4 ATP
Net “visible” ATP produced = 2.
产生的净“可见”ATP = 2。

Immediately upon finishing glycolysis, the cell must continue respiration in either an aerobic or anaerobic direction; this choice is made based on the circumstances of the particular cell. A cell that can perform aerobic respiration and which finds itself in the presence of oxygen will continue on to the aerobic citric acid cycle in the mitochondria. If a cell able to perform aerobic respiration is in a situation where there is no oxygen (such as muscles under extreme exertion), it will move into a type of anaerobic respiration called homolactic fermentation. Some cells such as yeast are unable to carry out aerobic respiration and will automatically move into a type of anaerobic respiration called alcoholic fermentation.
糖酵解结束后，细胞必须立即继续以有氧或无氧方向进行呼吸；这种选择是根据特定小区的情况做出的。能够进行有氧呼吸并且处于氧气存在下的细胞将继续在线粒体中进行有氧柠檬酸循环。如果一个能够进行有氧呼吸的细胞处于没有氧气的情况下（例如肌肉处于极度劳累状态），它就会进入一种无氧呼吸，称为同型乳酸发酵。有些细胞（例如酵母）无法进行有氧呼吸，会自动进行无氧呼吸，称为酒精发酵。