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Steroids are small molecules - much smaller than proteins - smaller molecules that tend to be hydrophobic or lipid soluble.
类固醇是小分子物质,比蛋白质小得多,这类小分子是非水溶性的,或者说是脂溶性的
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But you know, sometimes what seems to be the virtuous may not necessarily be, so that would be an example.
但是现在你们知道了,有时候看起来低脂的食物并不一定低脂,这是个很好的例子
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Fatty acid chains are fat molecules, they behave, if you have a lot of them in solution like oil.
脂肪酸链就是脂肪分子,它们看上去好像,如果你见过富含脂类的溶液,比如油
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But then they can also be toxic if taken in too large of amounts because the body does store them.
但如果摄入过量也会中毒,因为机体储存的脂溶性维生素也会过量
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So most of the lipids, which make up cell membranes in your body are of this category of phospholipids.
大部分脂类,那些在你体内构成细胞膜的脂类,都属于磷脂类
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Eating a high fat diet but one that's low in cholesterol can still potentially lead to high cholesterol levels.
食用高脂但低胆固醇的食物,仍可导致胆固醇含量偏高
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It has to be small, and it has to be lipid soluble in order for it to pass through a cell membrane.
这些分子必须非常小,而且必须是脂溶性的,才能穿过细胞膜
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I mentioned a little bit that this membrane is not just lipid bilayer but there's also proteins that are inserted into the membrane.
我之前说过,这层膜不仅仅是一层脂质双分子层,而是有很多蛋白质嵌插在膜上的
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There's lipid chains in between so cell membranes are lipid rich layers that can exist in water.
脂质链在两者中间,所以细胞膜是富含脂类的膜层,并可以稳定存在于水中
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Lipids are really complex molecules on their own right, but because of their particular kind of complexity they allow certain biological structures to form.
脂类本身是非常复杂的分子,但正是它们独特的复杂性,使它们能够形成某些生物结构
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One of the hypotheses that was being tested in this particular study was that a low-fat diet would reduce a woman's risk for breast cancer.
其中一个,在研究中被检验的假设是,低脂膳食,有助于降低妇女患乳腺癌的风险
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The lipids will form a bi-layer where the water soluble part of the lipid points out of this layer and the oily part points in.
脂质会形成双层膜,水溶性部分朝向膜层外,而脂溶性的部分朝向双层膜内部
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Doesn't it make sense then that being sedentary and seeking out high fat, high sugar, high calorie foods has become a priority woven into our biology?
我们的生物学天性,即静养至上,寻求高脂高糖高热量的饮食,是有一定的道理的
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They're small molecules, they're lipid soluble, they can go from extracellular to intracellular.
它们是小分子,并且是脂溶性的,它们能从胞外进入胞内
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I'll talk about biological membranes and lipids and how they're assembled.
我会讲到生物膜和脂质,及它们是如何组装成质膜的
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You want to look at the effect of a low fat diet.
你想要知道低脂饮食的效果如何
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There are different kinds of cell walls in bacteria but they have a rigid cell wall and our cells don't have a rigid cell wall, we have a fluid lipid like cell wall.
细菌有不同种类的细胞壁,但都很坚固,人类细胞没有坚固的细胞壁,我们有一层类似细胞壁的流动的脂类
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They're water soluble and fat soluble vitamins that look like this, and the difference between the two is that the fat soluble vitamins when they're ingested, gets stored in the body fat primarily in the liver.
分为脂溶性维生素和水溶性维生素,像这样,二者的区别在于,脂溶性维生素一经摄取,大多都储存在肝脏的脂肪中
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Because if you were unfettered by all those environmental things that make people eat different kinds of foods, most of you would probably like the high fat, high sugar foods better; most of you probably still do.
因为如果你可以不受这些环境因素影响,摆脱让人们吃各种不同的食物的外因,大部分人都会更喜欢高脂食品,或者高糖食品,你们中的大部分人可能依然如此
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Gram for gram it provides a lot more punch in terms of calories than protein or carbohydrate, and that could be why fat has such an appeal to human physiology and why people like high fat foods.
每克脂肪比蛋白质或碳水化合物,提供更多卡路里的热量,这是人类身体对脂肪如此渴求的原因,人们为什么如此喜欢高脂食物
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Because humans want to eat a lot, they want to bank their calories, they want to seek out foods that are high in sugar, fat, and variety, and if those are available then they're going to be eaten and we've got problems.
人们想要多吃,需要储存能量,人们一直在寻找高糖高脂的食物,如果找到,他们就会全部吃掉,然后我们就有麻烦了
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The water soluble vitamins tend to be used more immediately by the body not stored and excreted through the urine if consumed in excess, so the body can tolerate more variation in intake of these before you start getting toxicity than is the case with the vitamins on the right.
而水溶性维生素往往都立刻被身体所利用,不会被机体储藏,过剩部分由尿液排出,因此机体耐受过量水溶性维生素的能力,相比起右边这栏里的脂溶性维生素,可是要强得多了
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I do want to talk about one important subject which you might not have thought too much about and that's lipids, because lipids are so important to the structure of the body because they make up the membranes that form the cells that are the fundamental units.
我的确想要讨论一个重要的主题,这个主题也许你们都没有深入思考过,那就是关于脂类的问题,脂类对身体结构形成十分重要,它是组成细胞膜的基本单位,而细胞膜能够维持细胞形态
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There can be a supply of them, a storehouse of them that can build up in the body, and so day-to-day fluctuations become less of a problem with fat soluble then water soluble vitamins, because the body can go grab them from a storage depot, if you will.
从而在体内建立起一个供应源,一个脂溶性维生素仓库,这样一来,相比起水溶性维生素,脂溶性维生素的浓度不会每天剧烈波动,因为机体可以任意取用体内的储存
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So tens or hundreds of millions of dollars would go into a study like this by the time it was completed, money that could have been used for other things, to test whether eating a low fat diet would reduce risk for breast cancer.
数以百万计的美元,投入到这样的研究,当研究结束时,本可以用来做其他事情的钱,被用来检测是否低脂膳食,可降低患乳腺癌风险
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As I mentioned in the earlier class, most of you would probably rather have some high fat food like French fries or ice cream, or some type of a dessert than have cauliflower or have broccoli or have brussel sprouts.
就像我前面提到的,你们大部分人都宁愿,食用高脂食品,诸如炸薯条或冰激凌,或者一些甜点,而不是花椰菜,西兰花或是抱子甘蓝
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In any event, the saturated fats that are in these kinds of foods tend to be in the things that you associate with fatty foods like high fat meat, whole milk, etc., have a bad impact.
不论如何,这些食物中的饱和脂肪,正是你们通常称为高脂食品,如肥肉,全脂牛奶等,都是有害的
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And so these are the things people care about a lot and they're the ones that popular diet books are built around almost exclusively: that you should eat low fat, you should eat low carbs, high fat, they're all kinds of permutations of these that exist out there.
所以大量营养素是人们所关注的,它们也是,现在流行的饮食书籍所围绕的话题,类似人们应该吃的低脂或者应该低碳高脂,各种各样的说法都有
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I talked about just not using viruses but using plasmid DNA together with lipids and that's another strategy for gene therapy.
这一部分我们不仅讲了病毒的应用,也讲了利用脂质体包裹的质粒DNA,基因治疗还有其它的策略
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They're lipids but they also have a charged portion, a positively charged portion which interacts with DNA.
它虽然是脂类,但一部分带有电荷,其带有的正电荷将与DNA产生静电作用
应用推荐