Shadowing Practice: PCR (Polymerase Chain Reaction) - Learn English Speaking with Video

Bir pratik modu seçin

Her mod tam ekran bir pratik odası açar.

99 cümleler

Cümleler çok kısa veya çok uzun ise, ayarlamak için Düzenle'ye tıklayın.

There are some pieces of technology you really develop an appreciation for.

Maybe it's your phone, your laptop, your drawing tablet, but for me, it is the copy machine.

Oh, the copy machine.

I know it's not possible, but I could promise you that whenever the copy machine was aware of my presence, that's when it decided to malfunction,

especially if it knew I was short on time.

And of course, when it jams, the fancy copy machines will even tell you what is wrong and how to fix it,

but my experience with trying to follow the instructions of fixing the copy machine makes it worse, and then by that point there's a line,

and you feel your heart pounding, and you're embarrassed because now you've jammed it for everyone.

Yeah, so while I've developed an appreciation and respect for the copy machine, I've definitely tried to limit my use of it over the years.

Saves paper anyway.

You may be wondering why is she spending so much time on this?

Well I want to call your attention to a technology, a biotechnology, that works almost like an amazing and fancy copy machine.

Except not for something on paper.

No, it's for DNA.

This biotechnology is PCR.

Polymerase Chain Reaction, or PCR for short.

It provides a way to make more copies of a portion of DNA.

Lots and lots and lots of DNA copies, and this technology does NOT need to happen in a cell either.

In fact, it can happen in a test tube.

And so you may wonder, number one, how does PCR work?

And number two, why?

Why make more copies of some specific portion of DNA?

So let's briefly answer those two questions.

To answer the first question, the how does this work question,

let's talk about what we need first before we get to the steps of how it works.

We need the DNA portion that we want to make copies of, we need some kind of buffer to put it in,

and then we need things that would be necessary to make more copies of the DNA.

So think about what that might mean from our DNA replication video.

We'll need primers.

Recall that primers help DNA polymerase, a building enzyme, know where to go to start its building.

We need DNA polymerase, the building enzyme.

Fun fact, the DNA polymerase used is often a heat -resistant type of DNA polymerase as PCR uses heat.

Typically, the polymerase chosen for the job is tach polymerase, a type of of heat -resistant DNA polymerase.

Tac polymerase is originally from a type of bacteria that can handle and live in really high temperatures in nature, in hot springs.

Pretty cool.

We also need DNA nucleotides for the DNA polymerase to build with.

So we can look at the PCR sequence in three major steps.

We'll illustrate with one double -stranded DNA molecule here, and let's assume this is what we want replicated.

Step 1.

Denaturation.

You've heard that word denature before, right, when we were talking about enzymes?

One way we had talked about denaturing enzymes was using heat.

And heat is what we will use in this step.

This step involves the addition of heat needed to separate the two strands of the DNA molecule.

Step 2.

Annealing.

This word means something a little different in biology.

Basically this is when the two DNA strands

that now have been separated by that heat are going to be cooled and be joined by the primers.

The temperature for this step should allow the primers to bind to the specific segment of DNA that you want to amplify,

which means make copies of.

Step 3.

DNA synthesis.

Remember, synthesis means to make something.

With DNA synthesis, we're going to make more copies of DNA, and to do so, DNA polymerase will begin to work on both of these strands

and it will use the DNA nucleotides as its building material to amplify the DNA.

We should note that the temperature at this step may be a little warmer than the previous step.

It needs to be a temperature that is ideal for the specific DNA polymerase used.

Now after finishing one cycle of this, you have two double -stranded DNA molecules, right?

Similar to how it would be in DNA replication within a cell.

But you can repeat this now, except this time you now have two double -stranded DNA molecules to start with.

So you repeat with the denaturation, annealing, and DNA synthesis steps, now you have four double -stranded DNA molecules.

You repeat the steps again, now you have eight.

And if the process is automated by a machine, which, why yes, they do have in science catalogs, you can actually do this fairly quickly.

Which brings you to, why?

Why do this?

Well, any technology that needs copies of a portion of DNA could find PCR useful, but But we'll just mention two examples in our limited time.

We mentioned DNA fingerprinting in our gel electrophoresis video, and we mentioned that DNA fingerprinting can be part of a crime scene investigation.

Well, in order to have enough copies of DNA samples to run in gel electrophoresis to analyze,

PCR can be performed to make copies of the of the fragments of DNA that are found at a crime scene.

Another example?

Diagnosis of a disease, such as one caused by a virus.

For an especially relevant example, I can mention one of the testing types done for the virus that causes COVID -19.

COVID -19 is a pandemic that we're experiencing right now in 2020.

And the virus that causes COVID -19 is called SARS -CoV -2.

You might have heard of one test type that uses a sample from a nose or throat swab in a PCR test,

but to be more specific, this test for this virus is a real -time reverse transcription PCR test.

The reason it has this fancier reverse transcription in there is

because this virus uses RNA as its genetic material instead of DNA,

and you have to use an enzyme called reverse transcriptase to convert the RNA into DNA.

So before we can do the regular PCR steps we've mentioned, we must convert isolated and purified RNA into DNA.

A specific primer is added that will bind to an area of viral RNA,

and then reverse transcriptase is used to convert viral RNA into cDNA .

Using specific primers and the TAC DNA polymerase,

the cDNA can be copied over and over each cycle in the familiar steps we've been mentioning of PCR.

See the goal is you need enough copies of the viral cDNA in order for it to be detectable.

The idea being if it's a positive result, you have the selective primers binding and you have the TAC DNA polymerase making more

and more copies of the viral cDNA each cycle.

In addition, specific fluorescent probes are also used for identification.

A certain level is needed for identification of a positive result.

And if the virus's genetic material is not present in the sample, then primers wouldn't bind, and there would be no cDNA copies produced.

If you'd like to learn more about this test as far as its limitations

and also its complexity as we're being pretty general here, we've included some further reading suggestions in the video details.

So those were just two examples of how PCR can be used,

but there are many more examples in our suggested further reading links in the video description.

Overall, PCR is such a useful and fascinating technology that will likely remain indispensable for future uses.

It's a rare day when I pull out that word, indispensable.

Well, that's it for the Amoeba Sisters, and we remind you to stay curious.

I'll see you next time.

Uygulamayı İndir

Akıcı konuşmak için ihtiyacınız olan her şey

AI TelaffuzHer cümleyi puanla

IPA AlıştırmasıHer sesi ustalaştır

Kelime BilgisiKelime bankanızı oluşturun

Kelime OyunuOynarken öğrenin

QR Tara

Download on theApp Store Get it onGoogle Play

Aynı Kanal

Mitosis vs. Meiosis: Side by Side Comparison

Daily ConversationUniversity Students

Stroll Through the Playlist (a Biology Review)

Daily ConversationHigh School Students

Mitosis: The Amazing Cell Process that Uses Division to Multiply! (Older Video 2016 )

IELTS PrepTOEFL PrepUniversity Students

Circulatory System and Pathway of Blood Through the Heart

Cambridge Exam PrepHigh School StudentsUniversity Students

FOR YOU

Video Öner

239 cümleler

Bu dersin kelimeleri ve konuşma notları

En çok tekrarlanan kelimeler: Dna, Pcr, polymerase, step, copies. Bu videoda gölgeleme çalışması için 83 cümle ve 1299 kelime var. Konuşma bölümü 7:30 sürüyor. Konuşmacı dakikada yaklaşık 173 kelimeyle, günlük konuşmaya yakın doğal bir hızda konuşuyor. Kelimelerin yalnızca %81’i İngilizcede en sık kullanılan 3.000 kelime arasında, bu yüzden kelime dağarcığı zorlayıcı.

Bu videodaki önemli kelimeler

Videodan öğrenmeye değer 15 kelime, telaffuzu ve anlamıyla:

Kelime	Telaffuz	Anlam
virus isim	/ˈvaɪ.ɹəs/	virüs
enzyme isim	/ˈɛn.zaɪm/	enzim
molecule isim	/ˈmɑ.lɪ.kjul/	molekül
viral sıfat	/ˈvaɪɹəl/	viral
fancy isim	/ˈfæn.si/	yaratıcılık
convert fiil	/kənˈvɝt/	dönüştürmek
jam isim	/ˈd͡ʒæm/	reçel, murabba
resistant sıfat	/ɹəˈzɪstənt/	dirençli
curious sıfat	/ˈkjʊɹ.i.əs/	meraklı
remind fiil	/ɹəˈmaɪnd/	hatırlatmak, anımsatmak
tube isim	/tuːb/	tüp
throat isim	/ˈθɹoʊt/	boğaz
laptop isim	/ˈlæp.tɑp/	dizüstü, dizüstü bilgisayar
suggestion isim	/səˈd͡ʒɛst.ʃən/	öneri, teklif
biology isim	/baɪˈɑ.lə.d͡ʒi/	biyoloji, dirim bilimi

Tekrar etmeye değer cümleler

Videodan, günlük konuşmada yeniden kullanabileceğiniz kısa ve tam cümleler:

You’ve heard that word “denature” before, right?
When we were talking about enzymes?
Which brings you to…why?

Bu videodaki dil bilgisi

Konuşmacının en çok kullandığı yapılar, videodaki sözcüklerin aynısıyla:

Yapı	Videoda
Edilgen yapı be + fiilin üçüncü hâli — kimin yaptığı değil, ne olduğu önemli	have been separated · is automated · can be performed
Present perfect have/has + fiilin üçüncü hâli — geçmişte olan ama şimdi de önemli olan bir eylem	you've jammed · I've developed · You've heard

Dikkat edilecek telaffuzlar

Konuşmacı we'll, we're, we've gibi kısaltılmış biçimleri 16 kez kullanıyor. Bunları duyduğunuz gibi kısa söyleyin.

“th” sesleri: synthesis /ˈsɪnθəsɪs/, throat /ˈθɹoʊt/
“sh” ve “zh” sesleri: identification /aɪˌdɛn(t)ɪfɪˈkeɪʃn̩/, appreciation /əˌpɹiː.ʃiˈeɪ.ʃən/, transcription /tɹænˈskɹɪpʃən/, suggestion /səˈd͡ʒɛst.ʃən/, instruction /ɪnˈstɹʌkʃən/
Uzun kelimeler — vurguyu doğru yere koyun: identification /aɪˌdɛn(t)ɪfɪˈkeɪʃn̩/, appreciation /əˌpɹiː.ʃiˈeɪ.ʃən/, biology /baɪˈɑ.lə.d͡ʒi/, complexity /kəmˈplɛk.sɪ.ti/, limitation /lɪmɪˈteɪʃən/

Türkçe konuşanların zorlandığı sesler:

/w/ — dudaklar yuvarlak, /v/ değil: sequence /ˈsiː.kwəns/, swab /swɒb/
Kelime başındaki ünsüz kümesi — araya ünlü eklemeyin: strand /ˈstɹænd/, transcription /tɹænˈskɹɪpʃən/, curious /ˈkjʊɹ.i.əs/, throat /ˈθɹoʊt/, briefly /ˈbɹiːfli/
/æ/ — “e”den daha açık: strand /ˈstɹænd/, fancy /ˈfæn.si/, jam /ˈd͡ʒæm/, transcription /tɹænˈskɹɪpʃən/, laptop /ˈlæp.tɑp/

Bu videoyla nasıl çalışılır

Videonun tamamını konuşmadan bir kez dinleyin ve bilmediğiniz kelimeleri not edin.
0,75× hızla başlayın, cümle cümle tekrar edin ve kolaylaşınca normal hıza dönün.
Kendinizi kaydedin ve orijinaliyle karşılaştırın; virus, enzyme, molecule gibi kelimelere özellikle dikkat edin.

Gölgeleme Tekniği Nedir?

Gölgeleme, başlangıçta profesyonel tercüman eğitimi için geliştirilen ve çok dilli Dr. Alexander Arguelles tarafından popüler hale getirilen, bilim destekli bir dil öğrenme tekniğidir. Yöntem basit ama güçlüdür: ana dili İngilizce olan bir sesi dinler ve hemen yüksek sesle tekrar edersiniz — konuşmacıyı 1-2 saniye gecikmeyle takip eden bir gölge gibi. Pasif dinleme veya dilbilgisi alıştırmalarının aksine, gölgeleme beyninizi ve ağız kaslarınızı gerçek konuşma kalıplarını eşzamanlı olarak işlemeye ve yeniden üretmeye zorlar. Araştırmalar, telaffuz doğruluğu, tonlama, ritim, bağlı konuşma, dinleme anlama ve konuşma akıcılığını önemli ölçüde geliştirdiğini göstermektedir — bu da onu IELTS Konuşma hazırlığı ve gerçek dünya İngilizce iletişimi için en etkili yöntemlerden biri yapar.

Shadowing tekniği: adım adım eksiksiz rehberi okuyun →

Shadowing Practice: PCR (Polymerase Chain Reaction) - Learn English Speaking with Video

Bir pratik modu seçin

Uygulamayı İndir

Endocrine System

Mitosis vs. Meiosis: Side by Side Comparison

Stroll Through the Playlist (a Biology Review)

Mitosis: The Amazing Cell Process that Uses Division to Multiply! (Older Video 2016 )

Circulatory System and Pathway of Blood Through the Heart

4 How to use PCR and qPCR

Mental Debugging: How to Build Resilience After Failure

Structure and Function of a Prokaryotic Cell (Bacteria)

phienma

The Semiconductor Production Process Explained Clearly

Explanation of Vaccine Adjuvants

Bioprocessing Part 1: Fermentation

Can We Live Forever? – A Question of Science with Brian Cox

Antimycobacterials | Anti-TB Drugs

Phonetics and Phonology: Introduction

I Tested The Viral Reverse Engineering Repo

How did life begin? Abiogenesis. Origin of life from nonliving matter.