关注微信领¥50

百门课程¥0元


50万+已关注

GRE阅读模拟在线练习附答案一百二十七

2018-08-21 17:32:00来源:网络

  GRE阅读复习中,大家想要提高阅读速度,其实最好的方法就是利用真题来进行练习,通过真题的练习,大家能够更好地了解自己在备考中的不足,更好地备考GRE阅读考试。下面就是详细的内容整理!

点击查看》》》【GRE阅读真题在线练习附答案汇总】

  For some time scientists have believed that cholesterol plays a major role in heart disease because people with familial hypercholesterolemia, a genetic defect, have six to eight times the normal level of cholesterol in their blood and they invariably develop heart disease. These people lack cell-surface receptors for low- (10) density lipoproteins (LDL's), which are the fundamental carriers of blood cholesterol to the body cells that use cholesterol. Without an adequate number of cell-surface receptors to remove LDL's from the blood, the cholesterol-carrying LDL's remain in the blood, increasing blood cholesterol levels. Scientists also noticed that people with familial hypercholesterolemia appear to produce more LDL's than normal individuals. How, scientists wondered, could a genetic mutation that causes a slowdown in the removal of LDL's from the blood also result in an increase in the synthesis of this cholesterol-carrying protein?

  Since scientists could not experiment on human body tissue, their knowledge of familial hypercholesterolemia was severely limited. However, a breakthrough came in the laboratories of Yoshio Watanabe of Kobe University in Japan in 1980. Watanabe noticed that a male rabbit in his colony had ten times the normal concentration of cholesterol in its blood. By appropriate breeding, Watanabe obtained a strain of rabbits that had very high cholesterol levels. These rabbits spontaneously developed heart disease. To his surprise, Watanabe further found that the rabbits, like humans with familial hypercholes-terolemia, lacked LDL receptors. Thus, scientists could study these Watanabe rabbits to gain a better understanding of familial hypercholesterolemia in humans.

  Prior to the breakthrough at Kobe University, it was known that LDL's are secreted from the liver in the form of a precursor, called very low-density lipoproteins (VLDL's), which carry triglycerides as well as relatively small amounts of cholesterol. The triglycerides are removed from the VLDL's by fatty and other tissues. What remains is a remnant particle that must be removed from the blood. What scientists learned by studying the Watanabe rabbits is that the removal of the VLDL remnant requires the LDL receptor. Normally, the majority of the VLDL remnants go to the liver where they bind to LDL receptors and are degraded. In the Watanabe rabbit, due to a lack of LDL receptors on liver cells, the VLDL remnants remain in the blood and are eventually converted to LDL's. The LDL receptors thus have a dual effect in controlling LDL levels. They are necessary to prevent oversynthesis of LDL's from VLDL remnants and they are necessary for the normal removal of LDL's from the blood. With this knowledge, scientists are now well on the way to ward developing drugs that dramatically lower cholesterol levels in people afflicted with certain forms of familial hypercholesterolemia. 第二页继续...

本文关键字: GRE阅读练习 GRE阅读 GRE

更多>>
  • GRE阅读考试如何提高阅读速度

      为了帮助大家高效备考GRE,新东方在线GRE频道为大家带来GRE阅读考试如何提高阅读速度,希望对大家GRE备考有所帮助。更多精彩尽请关注新

    来源 : 网络 2018-10-17 16:16:50 关键字 : GRE阅读速度 GRE阅读 GRE

  • GRE逻辑阅读备考方法

      为了帮助大家高效备考GRE,新东方在线GRE频道为大家带来GRE逻辑阅读备考方法,希望对大家GRE备考有所帮助。更多精彩尽请关注新东方在线

    来源 : 网络 2018-10-16 15:46:55 关键字 : GRE逻辑 GRE阅读

  • GRE阅读对比题型全面解析

      为了帮助大家高效备考GRE,新东方在线GRE频道为大家带来GRE阅读对比题型全面解析,希望对大家GRE备考有所帮助。更多精彩尽请关注新东方

    来源 : 网络 2018-10-15 17:27:00 关键字 : GRE阅读题型 GRE阅读 GRE

  • GRE阅读复习常用的猜词技巧

      为了帮助大家高效备考GRE,新东方在线GRE频道为大家带来GRE阅读复习常用的猜词技巧,希望对大家GRE备考有所帮助。更多精彩尽请关注新东

    来源 : 网络 2018-10-12 17:56:00 关键字 : GRE阅读技巧 GRE阅读

  • GRE阅读长难句的练习方法

      为了帮助大家高效备考GRE,新东方在线GRE频道为大家带来GRE阅读长难句的练习方法,希望对大家GRE备考有所帮助。更多精彩尽请关注新东方

    来源 : 网络 2018-10-11 17:56:00 关键字 : GRE阅读长难句 GRE阅读

  • GRE阅读词汇积累

      为了帮助大家高效备考GRE,新东方在线GRE频道为大家带来GRE阅读词汇积累,希望对大家GRE备考有所帮助。更多精彩尽请关注新东方在线GRE

    来源 : 网络 2018-10-10 17:56:00 关键字 : GRE阅读词汇 GRE

  • GRE阅读短篇文章练习

      为了帮助大家高效备考GRE,新东方在线GRE频道为大家带来GRE阅读短篇文章练习,希望对大家GRE备考有所帮助。更多精彩尽请关注新东方在线

    来源 : 网络 2018-10-09 17:56:00 关键字 : GRE阅读文章 GRE阅读

  • GRE阅读文章遇到生词怎么办

      为了帮助大家高效备考GRE,新东方在线GRE频道为大家带来GRE阅读文章遇到生词怎么办,希望对大家GRE备考有所帮助。更多精彩尽请关注新东

    来源 : 网络 2018-10-08 17:56:00 关键字 : GRE阅读生词 GRE阅读

  • GRE阅读考试技巧整理

      为了帮助大家高效备考GRE,新东方在线GRE频道为大家带来GRE阅读考试技巧整理,希望对大家GRE备考有所帮助。更多精彩尽请关注新东方在线

    来源 : 网络 2018-10-07 17:56:00 关键字 : GRE阅读技巧 GRE阅读 GRE

  • GRE阅读解题步骤助力高分

      为了帮助大家高效备考GRE,新东方在线GRE频道为大家带来GRE阅读解题步骤助力高分,希望对大家GRE备考有所帮助。更多精彩尽请关注新东方

    来源 : 网络 2018-10-06 17:56:00 关键字 : GRE阅读步骤 GRE阅读

更多内容
更多>>

GRE词汇营第二季

GRE高频词汇GRE填空必背

5天搞定800组GRE近/反义词

价格 : ¥19.9

30人 已报名

查看详情
更多>>
更多公开课>>
更多>>
更多课程>>