PTE Summarize Spoken Text Exercise – DNA BARCODING

In PTE Academic exam, summarize spoken text and retell lecture questions are often from the real lectures or speech interception. One of the most repeated topics in PTE ‘Summarize Spoken Text’ is DNA & RNA. The lecture provided here is ‘DNA Barcoding’. To help the students, the team at English2language have collected “Summarize Spoken Text” lectures close to PTE real exam topics. You will be provided with PTE practice audio and question transcript here.

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PTE Summarize Spoken Text Exercise – DNA BARCODING

 

 

TRANSCRIPT

DNA barcoding was invented by Paul Hebert of the University of Guelph, in Ontario, Canada, in 2003. His idea was to generate a unique identification tag for each species based on a short stretch of DNA. Separating species would then be a simple task of sequencing this tiny bit of DNA. Dr Hebert proposed part of a gene called cytochrome c oxidase I (COI) as suitable to the task. All animals have it. It seems to vary enough, but not too much, to act as a reliable marker. And it is easily extracted, because it is one of a handful of genes found outside the cell nucleus, in structures called mitochondria.

The idea worked, and it has dramatically reduced the time (to less than an hour) and expense (to less than $2) of using DNA to identify species. And thus, in July this year, Dr Victor’s mystery goby became Coryphopterus kuna. It was the first vertebrate to have its DNA barcode—a sequence of about 600 genetic “letters”—included in its official description.

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  1. Saroj Verma
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