TED演讲:什么是脂肪(1)

 　　Olive oil is 100% fat; there's nothing else in it. 橄榄油含有100%的脂肪，除此之外没有别的。

　　Pancake mix, on the other hand, is only about 11% fat. 相反，煎饼只有约11%的脂肪。

　　And, yet, olive oil is good for you, and pancake mix is not. 然而，橄榄油对你的身体有益，煎饼则不然。

　　Why is that? 为什么会这样呢？

　　As it turns out, the amount of fat we eat doesn't impact our weight 原来，我们摄入的脂肪含量并不影响我们的体重、胆固醇，

　　or our cholesterol¹ or our risk of heart disease nearly as much as what kind of fat we eat. 或得心脏病的机率，这些只跟我们摄入的脂肪种类有关。

　　But let's back up: What is fat? 不过我们先回过头来看看：什么是脂肪？

　　If we were to zoom² in on a salmon³, which is a fatty fish, past the organs, past the tissues, into the cells, 如果我们把三文鱼放大，它是一种富含脂肪的鱼，忽略掉内脏和组织只看细胞的话，

　　we would see that the stuff we call fat is actually made up of molecules⁵ called triglycerides, and they are not all alike. 我们就会看到脂肪，它其实是是由一种叫做三酸甘油酯的分子组成的，而这些分子并不完全相似。

　　Here's one example. Those three carbons on the left, that's glycerol. 举个例子。左边的那三颗碳分子是甘油。

　　Now, you can think of that as the backbone⁶ that holds the rest of the molecule⁴ together. 你可以把它想像成骨干，能够把其它分子紧紧连在一起。

　　The three long chains on the right are called fatty acids, 右边的那三条长链被称为脂肪酸，

　　and it's subtle differences in the structures of these chains that determine whether a fat is, 这些分子链结构的微妙差别决定了脂肪种类。

　　let's say, solid or liquid; whether or not it goes rancid quickly; 比如，它们是固体还是液体，是否会很快变质，

　　and most importantly, how good or how bad it is for you. 最重要的是，对你是有益还是有害。

　　Let's take a look at some of these differences. 让我们来看看这些差别。

　　One is length. Fatty acids can be short or long. 一方面是长度。脂肪酸可长可短。

　　Another more important difference is the type of bond between the carbon atoms. 另一个更重要的区别是连接碳原子的碳键类型。

　　Some fatty acids have only single bonds. 有些脂肪酸只有单键。

　　Others have both single and double bonds. 另外一些则同时拥有单键和双键。

　　Fatty acids with only single bonds are called saturated⁷, and those with one or more double bonds are called unsaturated. 只有单键的脂肪酸叫做饱和脂肪酸，有单个或多个双键的脂肪酸则为不饱和脂肪酸。

　　Now, most unsaturated fats are good for you, while saturated fats are bad for you in excess. 大部分的不饱和脂肪酸对人体有益，而过多的饱和脂肪酸则是有害的。

　　For saturated fats, the story pretty much ends there but not for unsaturated fats. 就饱和脂肪酸而言，结果很简单，但不饱和脂肪酸不同。

　　The double bonds in these molecules have a kind of weird⁸ property; they're rigid⁹. 双键在这些分子中有一个奇怪特性，它们有十分坚固的刚性结构。

　　So, that means there are two ways to arrange every double bond. 这意味着双键排列有两种。

　　The first is like this, where both hydrogens are on same side and both carbons are on the same side. 第一种就像这样，两颗氢都在同一边，两颗碳也在同一边。

　　The second way is like this. 第二种方式像这样。

　　Now the hydrogens and carbons are on opposite sides of the double bond. 氢和碳在双键对立的两端。

1 cholesterol   

n.（U）胆固醇

参考例句：

• There is cholesterol in the cell of body.人体细胞里有胆固醇。
• They are determining the serum-protein and cholesterol levels.他们正在测定血清蛋白和胆固醇的浓度。

2 zoom   

n.急速上升；v.突然扩大，急速上升

参考例句：

• The airplane's zoom carried it above the clouds.飞机的陡直上升使它飞到云层之上。
• I live near an airport and the zoom of passing planes can be heard night and day.我住在一个飞机场附近，昼夜都能听到飞机飞过的嗡嗡声。

3 salmon   

n.鲑，大马哈鱼，橙红色的

参考例句：

• We saw a salmon jumping in the waterfall there.我们看见一条大马哈鱼在那边瀑布中跳跃。
• Do you have any fresh salmon in at the moment?现在有新鲜大马哈鱼卖吗？

4 molecule   

n.分子，克分子

参考例句：

• A molecule of water is made up of two atoms of hygrogen and one atom of oxygen.一个水分子是由P妈̬f婘̬ 妈̬成的。
• This gives us the structural formula of the molecule.这种方式给出了分子的结构式。

5 molecules   

分子( molecule的名词复数 )

参考例句：

• The structure of molecules can be seen under an electron microscope. 分子的结构可在电子显微镜下观察到。
• Inside the reactor the large molecules are cracked into smaller molecules. 在反应堆里，大分子裂变为小分子。

6 backbone   

n.脊骨，脊柱，骨干；刚毅，骨气

参考例句：

• The Chinese people have backbone.中国人民有骨气。
• The backbone is an articulate structure.脊椎骨是一种关节相连的结构。

7 saturated   

a.饱和的，充满的

参考例句：

• The continuous rain had saturated the soil. 连绵不断的雨把土地淋了个透。
• a saturated solution of sodium chloride 氯化钠饱和溶液

8 weird   

adj.古怪的，离奇的；怪诞的，神秘而可怕的

参考例句：

• From his weird behaviour,he seems a bit of an oddity.从他不寻常的行为看来，他好像有点怪。
• His weird clothes really gas me.他的怪衣裳简直笑死人。

9 rigid   

adj.严格的，死板的；刚硬的，僵硬的

参考例句：

• She became as rigid as adamant.她变得如顽石般的固执。
• The examination was so rigid that nearly all aspirants were ruled out.考试很严，几乎所有的考生都被淘汰了。