Molecules make you think of chemistry, right?

Well, they are also very important in biology.

In this video, we're going to look at carbohydrates, proteins and lipids.

在本視頻中，我們將瞭解碳水化合物、蛋白質和脂類。

When I say lipids, I'm talking about fats and oils.

Life processes depend on biological molecules, whose structure is related to their function.

生命過程依賴於生物分子，而生物分子的結構與其功能相關。

Did you know that living organisms are actually made from quite a small group of molecules?

你知道生物體實際上是由一小部分分子構成的嗎？

What do you think the most common molecule in you is?

你認為你體內最常見的分子是什麼？

About 55-60% of an adult human's body weight comes from water.

And in some organisms, this can be up to 90%.

在某些生物體中，這一比例可高達 90%。

Your muscles and kidneys are particularly watery, at about 79%, but even your bones are made up of 31% water.

肌肉和腎臟的含水量尤其高，約為 79%，但就連骨骼也由 31% 的水組成。

Imagine we removed all the water in your body.

想象一下，我們把你體內所有的水都抽走了。

Well, it would pretty much be just proteins, lipids, carbohydrates and nucleic acids such as DNA.

嗯，差不多就是蛋白質、脂類、碳水化合物和核酸（如 DNA）。

那麼，這些都是用什麼材料製成的呢？

Well, carbohydrates and lipids are really simple.

碳水化合物和脂類其實很簡單。

Proteins are a little more complex, with four or five elements.

蛋白質則稍微複雜一些，有四五種元素。

Carbon, hydrogen, oxygen, nitrogen and sometimes sulphur.

碳、氫、氧、氮，有時還有硫。

There are three main types of carbohydrate.

Monosaccharides, disaccharides and polysaccharides.

Simple sugars like glucose and fructose are monosaccharides.

葡萄糖和果糖等單糖屬於單糖。

Sucrose, which is made up of two simple sugars joined together, is a disaccharide.

蔗糖由兩種單糖連接而成，屬於雙糖。

And some carbohydrates are polymers that are made up of lots of sugars joined together and so are called polysaccharides.

有些碳水化合物是由許多糖連接在一起的聚合物，是以被稱為多糖。

Starch, glycogen and cellulose are three important polysaccharides.

澱粉、糖原和纖維素是三種重要的多糖。

Cellulose is found in plant walls and starch is the storage unit for surplus glucose made in photosynthesis.

纖維素存在於植物壁中，而澱粉則是光合作用產生的多餘葡萄糖的儲存組織、部門。

Glycogen is the storage unit used by animals for surplus glucose and is found in the liver and muscle tissue.

糖原是動物儲存多餘葡萄糖的組織、部門，存在於肝臟和肌肉組織中。

Starch is tested for using an iodine solution.

If the solution turns blue-black, then starch is present.

如果溶液變成藍黑色，則說明存在澱粉。

But whereas in carbohydrates the monomer or repeating unit was glucose, for proteins it's amino acids.

但是，碳水化合物的單體或重複組織、部門是葡萄糖，而蛋白質的單體或重複組織、部門是氨基酸。

The protein then folds up into a complex 3D shape, which is held together by weak bonds.

然後，蛋白質摺疊成複雜的三維形狀，並通過弱鍵固定在一起。

The function of each protein depends on its shape.

每種蛋白質的功能都取決於其形狀。

Because enzymes are proteins and the bonds holding proteins together are weak, this is why enzymes denature above certain temperatures.

由於酶是蛋白質，而蛋白質之間的結合力很弱，這就是酶在一定溫度下變性的原因。

The bonds are broken and the structure of the protein is changed.

鍵被破壞，蛋白質的結構也隨之改變。

There are 20 different amino acids that make up proteins.

The order of amino acids varies in different proteins and so 20 different amino acids means an almost infinite number of different proteins can be made.

不同蛋白質中氨基酸的排列順序各不相同，是以，20 種不同的氨基酸意味著幾乎可以製造出無數種不同的蛋白質。

It is estimated there are about 50,000 different proteins in the human body alone.

據估計，僅在人體內就有約 5 萬種不同的蛋白質。

You will come across proteins nearly everywhere.

For example, in cell membranes where they control the movement of substances during active transport, as enzymes, so in photosynthesis, respiration, DNA copying and digestion, as hormones, such as insulin, estrogen and testosterone, and as antibodies for fighting infection.

例如，在細胞膜中，它們控制著物質在主動運輸過程中的移動；作為酶，它們參與光合作用、呼吸作用、DNA 複製和消化；作為激素，如胰島素、雌激素和睪丸激素；作為抗體，它們用於抗感染。

這就是碳水化合物中的蛋白質。

These have a single glycerol molecule with three fatty acid tails attached.

它們有一個甘油分子，並附有三個脂肪酸尾部。

Different lipids contain different fatty acids.

不同的脂質含有不同的脂肪酸。

Triglycerides are a form of dietary fat found in meats, dairy and cooking oils.

甘油三酯是一種膳食脂肪，存在於肉類、奶製品和食用油中。

They are used by cells and tissue for energy or otherwise stored as fat.

它們被細胞和組織用於獲取能量，或以脂肪的形式儲存起來。

Some examples of lipids are steroid hormones, cholesterol, vitamin A and vitamin D.

脂質的一些例子包括類固醇激素、膽固醇、維生素 A 和維生素 D。

The three key biological molecules that are essential to living processes.

對生命過程至關重要的三種關鍵生物分子。

If you liked the video, give it a thumbs up and don't forget to subscribe.

如果您喜歡這段視頻，請豎起大拇指，別忘了訂閱。

如有任何問題，請在下方評論。

Why not check out our FewSchool app as well?

何不也試試我們的 FewSchool 應用程序？

生物分子 | 細胞 | 生物 | FuseSchool (Biological Molecules | Cells | Biology | FuseSchool)

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