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生物学:细胞结构概述 – 译学馆
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生物学:细胞结构概述

Biology: Cell Structure I Nucleus Medical Media

细胞结构概述
Cells are the smallest living units of an organism.
细胞是构成生物体的最小单位
All cells have three things in common
无论是什么类型的细胞
no matter what type of cell they are.
都有三个共同点
All cells have a cell membrane
所有细胞都有细胞膜
which separates the inside the cell from its environment,
细胞膜将细胞内的凝胶状物质:细胞质
cytoplasm, which is a jelly-like fluid,
以及细胞内的遗传物质:DNA
and DNA which is the cell’s genetic material.
与外界环境分隔开
There are two broad categories of cells.
细胞可分为两大类
The first category is eukaryotic cells.
第一种是真核细胞
They have organelles
真核细胞具有细胞器
which include the nucleus and other special parts.
包括细胞核和其它特殊结构
Eukaryotic cells are more advanced, complex cells
真核细胞是进化得更好的复杂细胞
such as those found in plants and animals.
比如植物和动物体内的细胞
The second category is prokaryotic cells.
另一种是原核细胞
They don’t have a nucleus or membrane enclosed organelles.
原核细胞没有细胞核和被膜包裹的细胞器
They do have genetic material
原核细胞内有遗传物质
but it’s not contained within a nucleus.
但遗传物质没有被核膜包裹起来
Prokaryotic cells are always one celled, or unicellular organisms,
原核细胞通常是单细胞生物
such as bacteria.
比如细菌
So what are organelles?
细胞器是什么?
Organelle means”little organ.”
细胞器就是“微型器官”
Organelles are the specialized parts of a cell
细胞器是细胞内的特殊结构
that have unique jobs to perform.
具有独特的功能
Let’s start with the nucleus, the control center of the cell.
我们从细胞的控制中心——细胞核说起
The nucleus contains DNA or genetic material.
细胞核内包含DNA 或遗传物质
DNA dictates what the cell is going to do
DNA负责调控细胞内的各项反应
and how it’s going to do it.
以及如何进行各项反应
Chromatin is the tangled, spread out form of DNA
染色质是互相缠绕 伸展状的DNA
found inside the nuclear membrane.
它们被包裹在核膜内
When a cell is ready to divide
当细胞准备分裂时
DNA condenses into structures known as chromosomes.
DNA就会浓缩形成染色体结构
The nucleus also contains a nucleolus,
细胞核内还有一个核仁
which is a structure where ribosomes are made.
核仁是产生核糖体的结构
After ribosomes leave the nucleus
核糖体离开细胞核后
they will have the important job of”synthesizing”, or making, proteins.
就会承担合成蛋白质这个重要的任务
Outside the nucleus
在细胞核外
the ribosomes and the rest of the organelles
核糖体和其他细胞器
float around in cytoplasm, which is the jelly-like substance.
漂浮在凝胶状的细胞质中
Ribosomes may wander freely within the cytoplasm
核糖体可以自由游离在细胞质中
or attach to the endoplasmic reticulum, sometimes abbreviated as ER.
也可以附着在内质网(ER)上
There are two types of ER:
内质网有两种
rough ER has ribosomes attached to it
附着了核糖体的粗面内质网
and smooth ER doesn’t have ribosomes attached to it.
和没有核糖体的光面内质网
The endoplasmic reticulum is a membrane enclosed passageway
内质网是闭合膜通道
for transporting materials
用于运输物质
such as the proteins synthesized by ribosomes.
比如核糖体生产的蛋白质
Proteins and other materials
蛋白质和其他物质
emerge from the endoplasmic reticulum
被包裹在内质网形成的运输小泡中
in small vesicles where the Golgi apparatus,
运输小泡被运往高尔基体
sometimes called the Golgi body receives them.
有时也称作高尔基复合体
As proteins move through the Golgi body
蛋白质通过高尔基体
they’re customized into forms that the cell can use.
被加工成细胞可以利用的形式
The Golgi body does this by folding the proteins into usable shapes.
高尔基体将蛋白质折叠成可利用的形状
or adding other materials on to them
或在上面加入其他物质
such as lipids or carbohydrates
如脂质或糖类
Vacuoles are sac-like structures that store different materials.
液泡是用来储存不同物质的囊状结构
Here, in this plant cell,
在左侧植物细胞中
the central vacuole stores water.
中央大液泡储存水
Going back to the animal cell,
再来看动物细胞
you’ll see an organelle called a lysosome.
里面有一种叫做溶酶体的细胞器
Lysosomes are the garbage collectors
溶酶体是废物回收器
that take in damaged or worn out cell parts.
可以回收受损或老化的细胞部件
They are filled with enzymes that break down this cellular debris.
溶酶体内充满了各种分解细胞碎片的酶
The mitochondrion in is an organelle that is the powerhouse for both animal and plant cells.
线粒体是动植物细胞的能量工厂
During a process called cellular respiration
在细胞呼吸过程中
the mitochondria make ATP molecules
线粒体产生ATP分子
that provide the energy for all the cells activities.
为所有细胞生命活动提供能量
Cells that need more energy
需要能量越多的细胞
have more mitochondria.
含有的线粒体就越多
Meanwhile the cell maintains its shape through a cytoskeleton.
同时 细胞靠细胞骨架维持自身形状
The cytoskeleton includes the thread-like microfilaments which are made of protein
细胞骨架包括由蛋白质构成的螺旋状微丝
and microtubules which are thin hollow tubes
和极细的空心微管
Some organisms such as plans that are photoautotrophic
一些生物 例如植物 是光能自养生物
meaning they capture sunlight for energy
它们从阳光中获得能量
have cells with an organelle called a chloroplast.
这是因为植物有叶绿体这种细胞器
The chloroplast is where photosynthesis happens
叶绿体是进行光合作用的场所
It’s green because it has a green pigment called chlorophyll.
因为内部含有绿色的叶绿素 所以呈绿色
Plant cells also have a cell wall outside of their cell membranes
植物细胞的细胞膜外还有一层细胞壁
that shape, support, and protect the plant cell.
起固定 支撑和保护细胞的作用
Animal cells never have a cell wall
动物细胞没有细胞壁
There are many other unique structures that only some cells have.
仅个别细胞具有某些特殊结构
Here are just a few.
这里列举几例
In humans, for example,
比如人类体内
the respiratory tract is lined with cells that have cilia.
呼吸道表面排列着具有纤毛的细胞
These are microscopic hair-like projections
这是一些极小的 发丝状的凸起物
that can move in waves.
随呼吸来回摆动
This feature helps trap inhaled particles in the air
这个特点有助于捕获随空气带入的颗粒物
and expels them when you cough.
然后在咳嗽时将颗粒物排出体外
Another unique feature in some cells is flagella.
一些细胞长着独特的鞭毛结构
Some bacteria have flagella.
一些细菌就长有鞭毛
A flagellum is like a little tail that
鞭毛像小尾巴一样
can help a cell move or propel itself.
帮助细菌移动
The only human cell that has a flagellum
人类只有一种细胞具有鞭毛
is a sperm cell.
那就是精子细胞
In summary remember:
知识点总结:
eukaryotic cells are plant and animal cells
真核细胞包括动植物细胞
with a nucleus and membrane-enclosed organelles
具有细胞核和被膜包裹的细胞器
While prokaryotic cells are unicellular organisms
而原核细胞是单细胞生物
without these things.
没有这些细胞结构
All cells have a cell membrane, cytoplasm and genetic material.
所有细胞都有细胞膜 细胞质和遗传物质
And even though only plant cells have chloroplasts
只有植物植物具有叶绿体
both plant and animal cells have mitochondria.
动植物细胞都有线粒体

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视频概述

简单介绍真核细胞与原核细胞的异同点,对比动植物细胞的特征和差异,以及各种细胞器的主要功能。

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视频来源

https://www.youtube.com/watch?v=URUJD5NEXC8

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