PTE Re-tell Lecture 真实讲座练习题:DNA和RNA

在PTE中,无论是Summarise Spoken Text 还是 Re-tell Lecture的考题大都是从真实的讲座或者演讲中截取的,中间经常经常夹杂很多不同的环境音.很多同学都反映有时未必是听不懂,而是听不到. 鉴于此,墨尔本文波雅思PTE专门为大家总结了真实讲座的PTE练习音频,相比新闻音频来说,整体更加接近PTE考试的真题,内容方面,我们也会为大家提供考试中存在的近似题,最近我们会持续更新,敬请期待!

How does this DNA recognition actually work and I want to show you here a 3D printed model of the cas 9 protein. So of course this complex how small it is. It’s really small, right, we can’t really see it with the, we certainly can’t see with a light microscope we can see maybe little specks using an electron microscope but to really understand the molecular structure of this complex we have to use a technique called X-ray crystallography, and this model is built using actual atomic coordinates that come from an X-ray crystallographic structure and we’re looking at here is the protein in white and its guiding our days. The orange molecule and that complex searches through self-looking for a DNA sequence that matches the sequence on the end of the guide RNA when that occurs it grabs onto the DNA so you can see this beautiful double helical structure here running through the protein and at the place where the sequence in the DNA matches the RNA and RNA DNA helix forms inside the protein that’s how recognition actually occurs and that displaces the other strand of the DNA and positions to molecular blades in the protein to make a precise double-stranded break in the DNA. that’s a cleaver that comes in and cuts the DNA when this kind of chemical interaction actually occurs.


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