MESELSON and STAHL - Evidence of semi-conservation replication for A-level Biology. DNA REPLICATION

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In this video, I go through the Meselson and Stahl experiment and how this proves that DNA replicates by semi-conservative replication
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29 сен 2024

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Комментарии : 145

@sridatlaraju7546 5 месяцев назад

Thank you very much mam. You are teaching the concept with basics which is best. I saw couple of videos before. But your video is helpful.

@MissEstruchBiology 5 месяцев назад

Thank you! Glad it helped

@duckIinq Год назад

5days till mock, gl everyone.. final boost🥹

@cinnamonrole2952 8 месяцев назад

Poooooo

@Artfull-Life 3 года назад

The point where we trnasfer bacteria form N15 medium to N14 medium and collected DNA at various intervals ...after 1or 2 replication we come to know that k n14 beacome incoparte in n15

@MissEstruchBiology 3 года назад

Hello You should be able to tell that N14 was incorporated after one division as the DNA would be lighter as one strand N15 and one strand N14. Hope that helps ☺

@Dzz1611 9 месяцев назад

Do i actually need to memorise this

@hi-ot3dt 8 месяцев назад

finally some Rosalind appreciation love how emphasised on the significant part !!!

@salmamamdouh4678 3 года назад

OMG!!! U ROCKKK I SWEARR. Our bio teacher had explained this 5 times and no one was able to understand. but this???? WOW!!

@MissEstruchBiology 3 года назад

aww thank you Salma! So glad I helped you get there with understanding this. Share with your classmates to hopefully help them too 🤞

@thelorenzo9719 4 года назад

Hello Miss Estruch, when do you finish and post the whole spec for AQA A level biology. Your videos are very much helpful

@MissEstruchBiology 4 года назад

Hello, All the Y12 content is nearly up and I am working on the final quarter of Y13 content. I can't put a date on it I'm afraid- I'm pregnant with twins at the moment which are due in September, so this will slow things down significantly on the upload front. Glad you are finding them so helpful

@thelorenzo9719 4 года назад

@@MissEstruchBiology Omds. I didn't know you were pregnant and almost due 😱😱. Please take as much time off and look after yourself xx

@MissEstruchBiology 4 года назад

@@thelorenzo9719 Thank you :) Good luck with your studies!

@melvinshinu4316 3 года назад

Honestly, your videos are so helpful. Thank you so much for making them!

@MissEstruchBiology 3 года назад

You're welcome and I'm so pleased they are helping you so much ☺

@KelvinHarawa-uj4ik Год назад

After watching so many videos on this experiment, I finally got the main idea behind the experiment and got to understand it,thank you so much🙏

@MissEstruchBiology Год назад

Yay 😁😁😁 So glad it helped make it click for you

@ttrc7404 3 года назад

fun fact.. crick was on lsd when he discovered the structure of DNA

@m.c.8794 3 года назад

here before the mock too?

@ttrc7404 3 года назад

@@m.c.8794 yeep what skl u at lol

@livharding875 4 года назад

Hi, great video, so glad have found your channel! Just checking for when it comes to revision, do your videos cover all y12 content? I.e would I cover everything I needed to know for y12 if I revised using your videos, if not, up to which topic is fully completed so I can be sure I’m covering all revision content? Tysm- Olivia

@MissEstruchBiology 4 года назад

Hi Olivia, Thanks for the comment, I'm really glad they videos are helping. Yes, the videos do cover all the theory for Y12. I haven't finished all the maths/practical/exam technique skills videos though, and these are also essential for preparing for the exams.

@livharding875 4 года назад

@@MissEstruchBiology they are, thank you! And okay, thank you very much, do you know when those ones will be done by? Completely understand if you don’t know. Also wondering if you know of any other biology resources such as textbooks or flashcards etc you can access/ buy on the internet that you think are useful and good for the aqa a level biology?

@MissEstruchBiology 4 года назад

@@livharding875 it will be a while. I am finishing the Y13 content for October and then I am going on maternity leave. Therefore the skills will be coming later in 2021 (some practicals/maths/exam tecnique skills are loaded already). If you have a look at the description on any of my videos I list the books and resources I recommend with links. You can also find this list on my website missestruch.com/new-a-level/ With regards to flashcards, I suggest making your own, and you can see my top 7 revision tips for the best way to make these.

@sophiecoughlan947 3 года назад

Thank you so so much you explain it so well!! I was struggling so much to understand it until I watched this.

@MissEstruchBiology 3 года назад

So pleased it helped you understand 😀

@ruoxi9113 3 года назад

most helpful video for explaining how the replication works down the generations ive seen by far!

@MissEstruchBiology 3 года назад

thank you 😊 Really pleased it was useful.

@merry2882 3 года назад

Thank you so much! I finally found a video that helps me to understand this

@MissEstruchBiology 3 года назад

Really pleased it helped you! 😊

@louisexxxxasasasa2567 Год назад

At 9:08, do all the 4 strands act as templates or just the 2 light strands? Thanks, great video!

@birdie7344 Год назад

all 4 strands

@vinoddaniel1778 Год назад

Hello Miss It's a little difficult concept to convey to students. Your explanation is quite helpful to my preparation of this concept. Regards 👍

@abbiexo2557 4 года назад

Thank u for these videos im failing so this is my only hope loool

@MissEstruchBiology 4 года назад

You got this! Good luck

@MontyNorman-y6e 5 месяцев назад

Remember be careful with anything electric as they could be harmful and or lethal to you and or other people and or start a fire along with causing other things. Remember be careful and stay safe.

@srm4802 2 года назад

You are an actual hero, love you! You don’t understand how helpful these videos are❤️!

@MissEstruchBiology 2 года назад

awww so happy the videos are helping so much!!!!

@kryptatrix_ 3 года назад

I couldn't understand this experiment at all but this video helped so much!! Thank you!

@MissEstruchBiology 3 года назад

That's great!! I'm so glad it helped you get your head around this experiment ☺☺

@graceoh389 2 года назад

This is the best video for me to understand this experiment! Thank you so much!

@MissEstruchBiology 2 года назад

You're so welcome, so pleased it helped you understand!

@Axxturel1288 7 месяцев назад

I don’t understand at 8:33 why you said there’s one strand of the n14 and one strand of the n15 dna when I thought it was supposed to be two strands for both as shown in the diagram

@reginadaka2335 3 года назад

Thank you so very much, u've helped me understand clearly

@MissEstruchBiology 3 года назад

You're very welcome ☺ So pleased that the content is helping you!

@birdie7344 Год назад

omg thank u so so much!! u made this so easy to understand :)

@MissEstruchBiology Год назад

I'm so pleased it helped 😀

@amira1897 3 года назад

Thank you💚the video is really helpful

@MissEstruchBiology 3 года назад

You're welcome 😊 Glad to hear it helped you

@chimwemwenamutowe4182 2 года назад

Best explanation I've come across so far, finally understood... Thank you

@MissEstruchBiology 2 года назад

I'm so pleased it helped!!! 😀 ☺️

@sama9875 3 года назад

Hi miss Estruch! I have a question regarding the DNA replication. According to the notes i've been given for this chapter, our teacher mentions that DNA polymerase catalyses the formation of hydrogen bonds between the bases and that DNA ligase catalyses the formation of phosphodiester bonds between the backbones of the newly formed strands. I've seen your reply on one of the comments saying DNA polymerase doesn't form hydrogen bonds and i'm really confused. If you can help me out i'd be really thankful! :) Amazing video by the way, i finally understood the experiment :D

@MissEstruchBiology 3 года назад

Hello, DNA polymerase catalyses the reaction to make the DNA polymer (as the name indicates ). The DNA nucleotides are held together to make the polymer by phosphodiester bonds. DNA ligase also forms phosphodiester bonds, but between small sections of the polymer (Okazaki fragments- but this isn't on the spec). Hydrogen bonds between the bases is NOT catalysed by DNA polymerase. This is heavily emphasised in AQA mark schemes. Hope that helps

@sama9875 3 года назад

@@MissEstruchBiology yeah, that helped a lot. thank you so much!!

@MissEstruchBiology 3 года назад

you're welcome 😊

@srooely7929 3 года назад

What type of question might we get on this? And how can we best approach them?

@MissEstruchBiology 3 года назад

These would all be application questions. Most commonly you would be shown the position of the DNA bands in a test tube for some of the generations and then you would have draw in the position of the DNA bands for the next generation of replication. Or, you could be shown the position of the DNA bands in all the test tubes and then asked to EXPLAIN the position (so talk about the proportion of heavy to light strands of DNA and then explain how this is a result of semi conservative replication). Hope that helps you.

@srooely7929 3 года назад

That’s very helpful :) Thank you so much! 💙

@official_jn2215 Год назад

So in the medium containing 14N, this sample had been growing its own E Coli bacteria too as well as the heavy DNA growing from bacteria in a medium containing 15N?

@bwembyamunshya8454 2 года назад

Best explanation I've come across .... miss Estruch 👏👏👏 I appreciate you so much ....

@MissEstruchBiology 2 года назад

aww thank you so much!!! So glad it helped you 😊😊

@bwembyamunshya8454 2 года назад

@@MissEstruchBiology keep up much love for you ♥️😘😘

@amankhobaib3588 2 года назад

Thankyou very much miss. Your videos are so helpful

@MissEstruchBiology 2 года назад

Thank you! I'm so pleased it's helped ☺️

@Aisha_khan1981 4 месяца назад

I have gone through several videos forthe explanation but non of them helped ,thankfully for the first time i get the best explanation ♥️

@Artfull-Life 3 года назад

Is There will be equal possibility ..,for dna n15 to incoprate either n15 or n14 dNA

@chika5264 3 года назад

Thank you soo muchh!! This video really helped me :)

@MissEstruchBiology 3 года назад

So pleased it helped you 😀

@akarovxn_6946 3 года назад

Would I need to know about the models and the experiment if I was doing OCR A?

@MissEstruchBiology 3 года назад

I just had a look at your specification and I can't seem to see it on there

@akarovxn_6946 3 года назад

@@MissEstruchBiology Thank you!!

@taktition_ 9 месяцев назад

Video starts at 5:56.

@alishamureed7906 3 года назад

This was so helpful... Thankyou so muchhh💖

@MissEstruchBiology 3 года назад

So pleased you found it helpful 😀

@ChristenasBlock 6 дней назад

Beautifully explained!

@MissEstruchBiology 5 дней назад

ah thanks!!

@ScarlettHamilton-o8x 11 месяцев назад

Hi, do we also need to understand the dispersive model?

@laundryandtaxes 10 месяцев назад

my teacher overcomplicated this so much

@MissEstruchBiology 10 месяцев назад

Glad it was more straightforward 😊

@jasminehodges5907 3 года назад

Thank u

@MissEstruchBiology 3 года назад

aww you're so welcome ☺

@toxins5803 Год назад

Do you need to have memorised this for the aqa spec?

@mehrunisaimmad8735 2 года назад

This can be used for the CIE board as well right?

@KK-mk8xb 3 года назад

these videos are so helpful! thank you!

@MissEstruchBiology 3 года назад

You're welcome, glad they are helping you 😊

@justsomeone2001 8 месяцев назад

Exam tomorrow, hope I ace it!!

@MissEstruchBiology 8 месяцев назад

Good luck!

@ismile21 Год назад

Thank u thank u❤️❤️❤️

@MissEstruchBiology Год назад

you're welcome 😊

@imtired5955 3 года назад

Omg thank thank you so much!!

@MissEstruchBiology 3 года назад

you're welcome 😊 Hope it helps you

@imtired5955 3 года назад

@@MissEstruchBiology it helped me so much that I was hoping to get a question regard this today

@Artfull-Life 3 года назад

But both time of dna strands are present is not possible that dna n15 stand mixed with other n15 strand instead of dna having n14?

@MissEstruchBiology 3 года назад

This is why this experiment was conducted, scientists were trying to discover whether DNA replication is conservative (as you describe in this comment) or semi-conservative. The results showed it must be semi-conservative.

@raha-12358 11 месяцев назад

the first time that i could understand the idea after watching so many videos. thank you!

@MissEstruchBiology 11 месяцев назад

yay! You're so welcome 😁😁

@abdulemalik8848 Год назад

Thank you very much .

@Artfull-Life 3 года назад

Actualyy i am pakistani and i cant breif my question in english

@MissEstruchBiology 3 года назад

Hello, Thats OK, I'll try my best

@hasnahh3379 Год назад

amazing video, helped sm thank you :)

@MissEstruchBiology Год назад

you're so welcome!

@jasonsingh9698 Год назад

Hi do we need to know about the dispersive hypothesis for a level biology for the aqa spec?

@MissEstruchBiology Год назад

no that's beyond the specification and an application example

@jasonsingh9698 Год назад

@@MissEstruchBiology okay thank you 😊

@laundryandtaxes 10 месяцев назад

BLESS UR SOUL

@zahrah9652 4 года назад

I get confused with where hydrogen bonds come into this. Does DNA polymerase form the hydrogen bonds between the bases or phosphodiester bonds? or do the hydrogen bonds reform themselves?

@MissEstruchBiology 4 года назад

Hydrogen bonds hold the two DNA polymer chains together to make DNA a double helix. DNA polymerase does not form hydrogen bonds. DNA polymerase forms phosphodiester bonds to join together DNA nucleotides to make a single DNA polymer chain. Hope that helps.

@merry2882 3 года назад

Yes the hydrogen bonds reform themselves

@yolishi7090 Год назад

You saved my exams!!!!! Thank you so much :))))

@MissEstruchBiology Год назад

ah wow! I am so happy my content has helped you

@Oman-sp5lg 3 года назад

Is there a copy of replicated DNA founded early and then they tried to find the appropriate way to reach it or what? they compared their results with what?

@MissEstruchBiology 3 года назад

Hello, I'm not sure exactly what you're asking. They isolated DNA from bacteria, allowed it to replicate and then compared the position of the DNA in the test tube pre and post replication. Hope that helps

@dizzle7759 Год назад

thank you for making this! extremely helpful :)

@MissEstruchBiology Год назад

you're welcome! So pleased it helped

@faithlaurenmartin1424 2 года назад

This was incredibly helpful. Subscribed.

@MissEstruchBiology 2 года назад

aww thank you!! So pleased it helped

@Dillaaa251 2 года назад

Hi. For the AQA spec do you need to know about purine and pyrimidine?

@MissEstruchBiology 2 года назад

Hey, no these are not on the AQA spec.

@Dillaaa251 2 года назад

@@MissEstruchBiology Thank you!

@haabeel7702 2 года назад

cheers

@nikithajustine 3 года назад

ugh I still don't understand.. someone needs to explain this to me in dummy terms

@MissEstruchBiology 3 года назад

If you have any questions that might help you understand then ask away

@nikithajustine 3 года назад

@@MissEstruchBiology I understand the part until 8:45.. why do they need a replicate another time, hasn't semi conservative replication happened already, like there is a original strand and new strand already formed?

@MissEstruchBiology 3 года назад

Hello, yes you are right it had. But then semi-conservative replication happened again so that even more cells could be made. This whole experiment is continual replication making more bacterial cells, not replication continually happening in one cell. I hope that helps.

@shomiya7677 2 года назад

Hi sister, pls tell me is it edexel?

@MissEstruchBiology 2 года назад

this is for AQA

@saeidsharafi987 3 года назад

can i have your power point?

@MissEstruchBiology 3 года назад

Hi, All my PowerPoints are on the Miss Estruch Biology TES Shop.

@Artfull-Life 3 года назад

I had a question can i ask

@MissEstruchBiology 3 года назад

Hello, ask away 😊

@megansilver5722 2 года назад

Absolute life saver!

@MissEstruchBiology 2 года назад

So happy it's helped you!!! ☺️

@bandit9686 Год назад

11:00

@ehsansurid8554 2 года назад

thank you miss.

@MissEstruchBiology 2 года назад

you're so welcome 😊

@idk-uv9dk 2 года назад

Brilliant vid!

@MissEstruchBiology 2 года назад

Thank you!! So pleased you think so.

@Arianbazyani 2 года назад

bless you

@MissEstruchBiology 2 года назад

Thank you!!

@naturelife-forms 8 месяцев назад

You have discussed every basics and fundamental points of Meselson and Stahl experiment and my all the doubts regarding the semi-conservative replication phenomenon have been cleared by you ma'am . THANK YOU SO MUCH .

@MissEstruchBiology 8 месяцев назад

😁😁 so pleased it has helped you