細胞生物學雙語教案3(線粒體結(jié)構(gòu)與功能)(已修改)
2025-04-29 08:45 本頁面
【正文】 細胞生物學雙語教案3（線粒體結(jié)構(gòu)與功能） Mitochondrial SubstructureMitochondria contain two membranes, separated by a space. Both are the typical unit membrane (railroad track) in structure. Inside the space enclosed by the inner membrane is the matrix. This appears moderately dense and one may find strands of DNA, ribosomes, or small granules in the matrix. The mitochondria are able to code for part of their proteins with these molecular tools. The above cartoon shows the diagram of the mitochondrial membranes and the enclosed partments. How are mitochondria organized to be powerhouses?The food we eat is oxidized to produce highenergy electrons that are converted to stored energy. This energy is stored in high energy phosphate bonds in a molecule called adenosine triphosphate, or ATP. ATP is converted from adenosine diphosphate by adding the phosphate group with the highenergy bond. Various reactions in the cell can either use energy (whereby the ATP is converted back to ADP, releasing the high energy bond) or produce it (whereby the ATP is produced from ADP).Steps from glycolysis to the electron transport chain. Why are mitochondria important?Lets break down each of the steps so you can see how food turns into ATP energy packets and water. The food we eat must first be converted to basic chemicals that the cell can use. Some of the best energy supplying foods contain sugars or carbohydrates ...bread, for example. Using this as an example, the sugars are broken down by enzymes that split them into the simplest form of sugar which is called glucose. Then, glucose enters the cell by special molecules in the membrane called “glucose transporters”. Once inside the cell, glucose is broken down to make ATP in two pathways. The first pathway requires no oxygen and is called anaerobic metabolism. This pathway is called glycolysis and it occurs in the cytoplasm outside the mitochondria. During glycolysis, glucose is broken down into pyruvate. Other foods like fats can also be broken down for use as fuel (see following cartoon). Each reaction is designed to produce some hydrogen ions (electrons) that can be used to make energy packets (ATP). However, only 4 ATP molecules can be made by one molecule of glucose run through this pathway. That is why mitochondria and oxygen are so important. We need to contin
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