動畫：細胞結構

視頻： 生物學_細胞結構

Cells are the smallest living units of an organism.

細胞是生物體組成的最小的活動單元

All cells have three things in common

所有的細胞都在三種結構

no matter what type of cell they are.

不管它們是什麼類型的細胞

All cells have a cell membrane which separates the inside the cell from its environment,

所有的細胞都有細胞膜，將細胞內與環境分隔開

cytoplasm, which is a jelly-like fluid,

細胞質是一種果凍狀液體，

DNA是細胞的遺傳物質

There are two broad categories of cells.

細胞主要分為兩大類

The first category is eukaryotic cells.

第一類是真核細胞

They have organelles

他們有細胞器

which include the nucleus and other special parts.

包括細胞核和其他特殊結構

Eukaryotic cells are more advanced, complex cells

真核細胞是更先進和複雜的細胞

such as those found in plants and animals.

如植物、動物細胞

The second category is prokaryotic cells.

第二類是原核細胞

They don"t have a nucleus or membrane enclosed organelles.

他們沒有細胞核或膜包裹的細胞器

They do have genetic material but it"s not contained within a nucleus.

他們有遺傳物質，但並沒有細胞核的結構

Prokaryotic cells are always one celled,

原核細胞通常是只有一個細胞

or unicellular organisms, such as bacteria.

單細胞生物，如細菌

So what are organelles?

那麼，什麼是細胞器？

細胞器的意思是「小器官。」

Organelles are the specialized parts of a cell that have unique jobs to perform.

細胞器是細胞中特定的結構，可以執行獨特的工作

Let"s start with the nucleus, the control center of the cell.

讓我們先從細胞的中心細胞核說起

The nucleus contains DNA or genetic material.

細胞核包含DNA或遺傳物質

DNA dictates what the cell is going to do

DNA決定哪些細胞是幹什麼

and how it"s going to do it.

和怎麼干

Chromatin the tangled, spread out form of DNA found inside the nuclear membrane.

在核膜內，DNA以染色質的形式存在，

並互相纏繞、散開

When a cell is ready to divide

當一個細胞準備分裂

DNA condenses into structures known as chromosomes.

DNA凝集成稱為染色體的結構

The nucleus also contains a nucleolus,

細胞核中還包含一個核仁

which is a structure where ribosomes are made.

核仁是生產核糖體的工廠

After ribosomes leave the nucleus

當核糖體離開細胞核後

they will have the important job of "synthesizing",

他們的重要工作是「合成」

or making, proteins.

即生長蛋白質

除了細胞核、核糖體和其它細胞器

float around in cytoplasm, which is the jelly-like substance.

流動在細胞質，是果凍狀物質

Ribosomes may wander freely within the cytoplasm

核糖體可以在細胞質中自由活動

or attach to the endoplasmic reticulum, sometimes abbreviated as ER.

或連接到內質網(ER)

There are two types of ER:

有兩種類型的內質網

rough ER has ribosomes attached to it

有核糖體連接的內質網叫粗面內質網

and smooth ER doesn"t have ribosomes attached to it.

沒有核糖體連接的叫光面內質網

The endoplasmic reticulum

內質網

is a membrane enclosed passageway for transporting materials

是膜封閉的通道結構，用於轉動物質

such as the proteins synthesized by ribosomes.

如由核糖體合成的蛋白質

Proteins and other materials

蛋白質和其他物質

emerge from the endoplasmic reticulum

從內質網內形成

in small vesicles

小囊泡

where the Golgi apparatus, sometimes called the Golgi body

高爾基體

receives them.

接收它們

蛋白質通過高爾基體的加工

into forms that the cell can use.

形成有活性的蛋白質

The Golgi body does this by folding the proteins into usable shapes.

高爾基體通過摺疊蛋白質，形成有活性的形狀

or adding other materials on to them

或添加一些物質作為修飾

such as lipids

如脂類

or carbohydrates

或碳水化合物

Vacuoles are sac-like structures that store different materials.

液泡是儲存不同材料的囊狀結構

Here, in this plant cell, the central vacuole stores water.

植物細胞中，中央液泡儲存水。

Going back to the animal cell,

讓我們再回到動物細胞

you"ll see an organelle called a lysosome.

你會看到一種稱為「溶酶體」的細胞器。

Lysosomes are the garbage collectors

溶酶體是垃圾收集者

that take in damaged or worn out cell parts.

它們收集損壞或老化的細胞部分

They are filled with enzymes that break down this cellular debris.

它們充滿了可以將細胞破碎的酶

線粒體是一種細胞器，它是細胞的動力工廠

animal and plant cells.

動物和植物細胞一樣

During a process called cellular respiration

這一過程叫做細胞呼吸

the mitochondria make ATP molecules

線粒體產生ATP分子

that provide the energy for all the cells activities.

他們提供所有細胞活動所需能量

Cells that need more energy

細胞需要更多能量

have more mitochondria.

就需要更多的線粒體

Meanwhile the cell maintains its shape

細胞通過細胞骨架

through a cytoskeleton.

保持其形狀

The cytoskeleton includes the thread-like microfilaments

細胞骨架包括線狀的微絲

which are made of protein

由蛋白質

and microtubules which are thin hollow tubes

和中空微管

Some organisms

有些生物

such as plans that are photoautotrophic

如植物是光合自養型

meaning they capture sunlight for energy

他們吸收陽光作為能源

細胞有一種叫「葉綠體」的細胞器

The chloroplast is where photosynthesis happens

葉綠體發生光合作用的場所

It"s green because it has a green pigment called

它們是綠色，是因為含有綠色素

chlorophyll.

葉綠素

Plant cells also have a cell wall outside of their cell membranes

植物細胞膜外還有細胞壁

that shape, support, and protect the plant cell.

功能是維持細胞形狀、支持和保護植物細胞

Animal cells never have a cell wall

動物細胞從來沒有細胞壁

There are many other unique structures that only some cells have.

它們有許多其他獨特的結果，但只在某些細胞中有

Here are just a few.

我們舉一些例子

In humans, for example, the respiratory tract is lined with cells that have cilia.

例如，人類呼吸道細胞有纖毛

These are microscopic hair-like projections

是微觀的毛髮狀突起

that can move in waves.

可在波浪運動

此功能可幫助你咳嗽時排除吸入顆粒

Another unique feature in some cells is flagella.

某些細胞的另一種特徵是鞭毛

Some bacteria have flagella.

一些細菌有鞭毛

A flagellum is like a little tail that can help a cell move or propel itself.

鞭毛就像一個小尾巴

可以幫助細胞移動

The only human cell that has a flagellum

人類唯一有鞭毛的細胞

is a sperm cell.

是精子細胞

In summary remember:

總之記住：

eukaryotic cells are plant and animal cells with a nucleus and membrane-enclosed organelles

真核細胞是植物和動物細胞

有細胞核和膜包圍的細胞器

While prokaryotic cells are unicellular organisms without these things.

原核細胞是沒有這些東西的單細胞生物

All cells have a cell membrane, cytoplasm and genetic material.

所有的細胞都有細胞膜，細胞質和遺傳物質

And even though only plant cells have chloroplasts

只有植物細胞有葉綠體

both plant and animal cells have mitochondria.

植物和動物細胞均有線粒體

丁香葉

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