章节大纲

  • 常规

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  • 主动传输

    A person pushing a large round stone uphill on a grassy slope.

     

    What does it take to roll a stone uphill?
    ::把石块卷上山坡需要什么?

    This round stone tends to roll downhill due to the force of gravity. It takes an input of  energy  to push it uphill. Due to  , molecules tend to move from an area of a large amount to an area of a small amount. So guess what it takes to move molecules the opposite way, from an area of low  concentration  to an area of high concentration? Energy, of course!
    ::这个圆石块由于引力而倾向于向下滚动。 它需要投入能量才能推向上坡。 由于 , 分子往往会从一个大面积的区域移动到一个小面积的区域。 所以猜猜用什么将分子以相反的方式移动, 从一个低密度区域移动到一个高浓度区域? 当然, 能量!

    Active Transport
    ::活动交通

    During  active transport,  molecules move from an area of low concentration to an area of high concentration. This is the opposite of  diffusion , and these molecules are said to flow  against their  concentration gradient .  Active transport is called "active" because this type of transport requires energy to move molecules.  ATP  is the most common source of energy for active transport.
    ::在活性迁移期间,分子从低浓度地区移到高浓度地区。这与扩散截然相反,这些分子据说会随其浓度梯度而流动。主动迁移被称为“活动”因为这种迁移需要动能来移动分子。ATP是活性迁移最常见的能源来源。

    As molecules are moving against their concentration gradients, active transport cannot occur without assistance. A  carrier protein  is always required in this process. Like  facilitated diffusion , a  protein  in the membrane carries the molecules across the membrane, except this protein moves the molecules from a low concentration to a high concentration. These proteins are often called "pumps" because they use energy to pump the molecules across the membrane. There are many  cells  in your body that use pumps to move molecules. For example, your  nerve  cells (neurons) would not send messages to your  brain  unless you had protein pumps moving molecules by active transport.
    ::分子随着其浓度梯度而移动, 没有帮助, 活性迁移无法发生。 在这个过程中, 总是需要一种载体蛋白。 像促进扩散一样, 膜中的蛋白质会携带分子横跨膜膜, 但这种蛋白会将分子从低浓度移动到高浓度。 这些蛋白经常被称为“ 泵 ” , 因为它们使用能量将分子泵泵跨膜。 您体内有许多细胞使用泵移动分子。 例如, 您的神经细胞( 中子) 不会将信息传送到脑部, 除非您有蛋白质泵通过活性迁移来移动分子 。

    The  sodium-potassium pump  ( Figure   ) is an example of an active transport pump. The sodium-potassium pump uses ATP to move three sodium (Na + ) ions and two potassium (K + ) ions to where they are already highly concentrated. Sodium ions move out of the cell, and potassium ions move into the cell. How do these ions then return to their original positions? As the ions now can flow down their concentration gradients, facilitated diffusion returns the ions to their original positions either inside or outside the cell.
    ::钠-钾泵(图)是活性运输泵的一个例子。钠-钾泵使用ATP将3个钠(Na+)离子和2个钾(K+)离子移到它们已经高度集中的地方。钠离子移出细胞,钾离子移入细胞。这些离子如何回到原来的位置?随着离子现在可以流到其浓度梯度下,促进扩散将离子返回到细胞内外的原始位置。

    The sodium-potassium pump transferring ions across a cell membrane.

     

    The sodium-potassium pump moves sodium ions to the outside of the cell and potassium ions to the inside of the cell, areas where these ions are already highly concentrated. ATP is required for the protein to change shape. ATP is converted into ADP (adenosine diphosphate) during active transport.
    ::钠-钾泵将钠离子移到细胞外部,将钾离子移到细胞内,这些离子已经高度集中的地区。蛋白质需要ATP来改变形状。ATP在活性运输期间将ADP(乙酸二磷酸酯)转换成ADP。

    Summary
    ::摘要

    • During active transport, a protein pump uses energy, in the form of ATP, to move molecules from an area of low concentration to an area of high concentration.
      ::在活性运输期间,蛋白质泵使用ATP形式的能量将分子从低浓度地区转移到高浓度地区。
    • An example of active transport is the sodium-potassium pump, which moves sodium ions to the outside of the cell and potassium ions to the inside of the cell.
      ::活性运输的一个例子是钠-钾泵,该泵将钠离子移到细胞外部,将钾离子移到细胞内部。

    Explore More
    ::探索更多

    Use the resource below to answer the questions that follow.
    ::利用以下资源回答以下问题。

    • Osmosis and Active Transport  at   (8:40)
      ::在8:40时(8:40时)进行骨质疏松和主动运输
    1. What is active transport?
      ::什么是主动运输?
    1. Where does a cell obtain the energy for active transport?
      ::电池在哪里获得主动运输的能量?
    1. How does the body prevent the loss of sugar in urine?
      ::身体如何防止尿中的糖流失?
    1. List three factors that affect the movement of materials across a membrane. Explain how these factors affect the movement of matter.
      ::列出影响材料跨膜移动的三种因素,解释这些因素如何影响物质流动。

    Review
    ::回顾

    1. How is active transport different from passive transport?
      ::主动运输与被动运输有何不同?
    1. What form of energy is usually used in active transport?
      ::哪种能源通常用于主动运输?
    1. Give an example of active transport. Explain what occurs during this process.
      ::举一个主动传输的例子。 请解释在此过程中发生的情况 。