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  • 电池电池运输 - 高级

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    What is cell transport?
    ::什么是手机运输?

    It is the movement of substances across the either into or out of the . Sometimes things just move through the . Other times, substances need the assistance of a , like a channel protein or some other transmembrane protein, to cross the cell membrane.
    ::这是物质在进进出出时的移动。有时事情只是通过。有时,物质需要像通道蛋白或者其他的转基因蛋白等帮助才能穿过细胞膜。

    Cell Transport
    ::电池电池运输

    Cell transport refers to the movement of substances across the cell membrane. Probably the most important feature of a cell's phospholipid membranes is that they are selectively permeable . A membrane that is selectively permeable , or semipermeable , has control over what molecules or ions can enter or leave the cell, as shown in Figure  . This feature allows a cell to control the transport of materials, as dictated by the cell's function. The permeability of a membrane is dependent on the organization and characteristics of the membrane and proteins. In this way, cell membranes help maintain a state of within cells (and tissues , organs , and organ systems) so that an organism can stay alive and healthy.
    ::细胞迁移是指细胞膜之间的物质移动。 细胞磷离心膜中最重要的特征可能是它们有选择性地渗透。 如图所示,选择性地渗透或半渗透的细胞膜可以控制分子或离子进入或离开细胞。这个特征允许细胞按照细胞的功能来控制材料的迁移。 细胞膜的渗透性取决于膜和蛋白质的组织和特性。 这样,细胞膜可以帮助保持细胞(和组织、器官和器官系统)内部的状态,使生物体能够保持生命和健康。

    lesson content
    A selectively permeable, or semipermeable, membrane allows certain molecules through, but not others.

    Transport Across Membranes
    ::横跨膜膜运输

    The molecular make-up of the phospholipid bilayer limits the types of molecules that can pass through it. For example, hydrophobic (water-hating) molecules, such as carbon dioxide (CO 2 ) and oxygen (O 2 ), can easily pass through the lipid bilayer, but ions such as calcium (Ca 2+ ) and polar molecules such as (H 2 O) cannot. The hydrophobic interior of the phospholipid bilayer does not allow ions or polar molecules through because they are hydrophilic , or water loving. In addition, large molecules such as sugars and proteins are too big to pass through the phospholipid bilayer. Transport proteins within the membrane allow these molecules to cross the membrane into or out of the cell. This way, polar molecules avoid contact with the nonpolar interior of the membrane, and large molecules are moved through large pores.
    ::磷素双层的分子构成限制了能够穿透该分子的分子类型。例如,诸如二氧化碳(CO2)和氧(O2)等疏水分子(缺水分子)很容易通过脂质双层,但诸如钙(Ca2+)和极分子(H2O)等离子体不能通过。磷素双层的疏水分子内部不允许离子或极分子通过这些分子,因为它们具有水利性或爱水。此外,糖和蛋白质等大型分子太大,无法通过磷素双层。在膜内运输蛋白使得这些分子能够跨过膜进入或流出细胞。这样,极分子就避免了与薄膜的非极性内部接触,而大型分子则通过大孔移动。

    Every cell is contained within a membrane punctuated with transport proteins that act as channels or pumps to let in or force out certain molecules. The purpose of the transport proteins is to protect the cell's internal environment and to keep its balance of salts, nutrients , and proteins within a range that keeps the cell and the organism alive.
    ::每个细胞都包含在膜内,带有运输蛋白,作为释放或强制释放某些分子的渠道或泵,运输蛋白的目的是保护细胞的内部环境,使其盐类、营养素和蛋白质的平衡保持在保持细胞和生物体活性的范围之内。

    There are four main ways that molecules can pass through a phospholipid membrane. The first way requires no energy input by the cell and is called simple . This type of transport includes passive diffusion and . No assistance by a transport protein is necessary in simple diffusion.  Facilitated diffusion , does involve the assistance of transport proteins. The third way, called , requires that the cell uses energy to pull in or pump out certain molecules and ions. Active transport involves proteins known as pumps. The fourth way is through vesicle transport , in which large molecules are moved across the membrane in bubble-like sacks that are made from pieces of the membrane. Vesicular transport includes exocytosis and endocytosis .
    ::分子可以通过四种主要途径通过磷离子膜穿透。 第一种途径不需要细胞输入能量,而称之为简单。 这种运输方式包括被动扩散和。 这种运输方式包括被动扩散。 在简单扩散方面不需要运输蛋白的帮助。 便利扩散确实需要运输蛋白的帮助。 第三种途径称为:要求细胞利用能量拉入或抽出某些分子和离子。 活动运输涉及被称为泵的蛋白质。 第四种途径是输卵管运输,其中大型分子通过由膜碎块制成的气泡状麻袋穿过膜。 肝脏运输包括排出性硬化和内分泌性硬化。

    Homeostasis and Cell Transport
    ::稳住和手机运输

    Homeostasis refers to the balance, or equilibrium, within the cell or a body. It is an organism's ability to keep a constant internal environment. Keeping a stable internal environment requires constant adjustments as conditions change inside and outside the cell. The adjusting of systems within a cell is referred to as homeostatic regulation. Because the internal and external environments of a cell are constantly changing, adjustments must be made continuously to stay at or near the normal proportions of all internal substances. This involves continual adjustments in transport of substances across the cell membrane. Homeostasis is a dynamic equilibrium rather than an unchanging state. The cellular processes discussed in the cell transport (passive and active transport) concepts all play an important role in homeostatic regulation.
    ::恒定状态是指细胞或身体内部的平衡或平衡。它是有机体保持一个稳定的内部环境的能力。 保持稳定的内部环境需要随着细胞内外条件的变化而不断调整。 细胞内部系统的调整称为自定状态调节。 由于细胞的内外环境不断变化,必须不断进行调整,以保持或接近所有内物质正常比例。 这需要不断调整细胞内膜之间的物质运输。 恒定状态是一种动态平衡,而不是一个不变状态。 细胞运输(被动和主动运输)概念中讨论的细胞过程在自定义状态调节中都起着重要作用。

    Summary
    ::摘要

    • The cell membrane is selectively permeable, allowing only certain substances to pass through.
      ::细胞膜有选择性地渗透,只允许某些物质通过。
    • Cell transport may require assistance by a protein/pump.
      ::电池运输可能需要蛋白质/泵的帮助。
    • Cell transport may require energy.
      ::电池运输可能需要能源。
    • Some transport involves vesicles.
      ::有些运输涉及输卵器。

    Review
    ::回顾

    1. What is meant by cell transport? Why is cell transport important?
      ::手机运输意味着什么?为什么手机运输很重要?
    2. List types of cell transport.
      ::电池运输种类清单。
    3. Explain how cell transport helps an organism maintain homeostasis.
      ::解释细胞运输如何帮助生物保持自足。