Where does the cell get the energy to do all this? That’s the role of the mitochondria. To make energy, the mitochondria take oxygen. This is the only reason why we breathe in, and adds electrons from the food we eat to make water molecules. That process also creates a high energy molecule called ATP, which the cell uses it to power all of its parts. Plant cells make energy a different way. They have chloroplasts. They combine carbon dioxide and water with light energy from the sun to create oxygen and sugar, a form of chemical energy. All the parts of the cell have to work together to keep things running smoothly. And all the cells of your body have to work together to keep you running smoothly. That’s a whole lot of cells. Scientists think there’re about 37 trillion of them.
细胞实现这些功能的能量从何而来？那是线粒体发挥了作用。为了制造能量，线粒体吸进氧气。这是我们吸入氧气的唯一原因，然后从我们摄入的食物中获取电子来制造水分子。这个过程同时制造出一个高能量分子，叫做三磷酸腺苷，它为细胞其他部分的运作提供能量。植物细胞的能量来源不同。它们有叶绿体。叶绿体把二氧化碳和水分与太阳光能量合成，制造氧气和糖分，一种化学能量。细胞所有部分必须得一起工作才能保证功能正常。你体内所有的细胞也必须一起工作使你一切正常。人体内有很多细胞。科学家们认为人体内有37万亿个细胞。
词汇讲解：
mitochondria /ˌmaɪtəˈkɑndriə/ pl. 线粒体
mitochondrion /ˌmaɪtoʊˈkɑːndriən/ s.
*phenomena & phenomenon 现象
combine…and/with…
把……和……组合在一起
work together to…
一起努力去……
keep you running smoothly
让你的身体运行流畅
a whole lot of很多
关于数字：
trillion
1000,000,000,000
1 trillion = 1000 billion
1 billion = 1000 million
1 million = 1000 thousand
