my final exam is tomorrow ... you were really helpful Mr.Andersen .. and our proffesor he's from Cambridge and only believe in the explain & mention & show & draw questions not a single mcq or t&f or even complete in the tests .. but i got he's attention on the midterms , he said you the only student that got an 96% on his exam , really your videos helped me a lot , thanks let's hope for the best in the final ..
thank you very much , you too man , that day in the exam as i expected all the questions were short answers and i let my imagination flow and that end up very well , good luck
Loooooool it took me almost an hour to understand it from my books and i still didnt get it.. and now it took me 5 min just by watching this video and everything is clear 😅😅 thx 👍👍
Thank you! I was panicking because I have a test in less than 2 days about this. Thank you so much for helping me understand this experiment. The simulation helped a lot.
I've seen this explained a lot of different ways, but this is a nice and concise way of doing it. Answering "What does that mean?" is super important. So is using scientific language for your explanation, prompting students to look it up.
Honestly I can still Not get my head around this experiment! I've looked on nearly every website+ videos+ text books and I still don't get it. How does it show semi-conservative replication and why did they use bacteria?
Well, this is going to be a very long explanation, but I hope this weird, simplified ''idea'' helps you out: Bacteria is one of the model organisms Geneticists and Cell Biologists use (along with Drosophila, Yeast, etc., these are quick and efficient). We do not want to experiment on our kind. Anyway, this shows the semi-conservative replication because as he stated, bacteria are grown in an isotope that is heavy. So we give bacteria an environment they can adjust to, where they feel good. So they will undergo normal replication, whereas all the DNA is stained with the heavy isotope. So, in this adjusted environment, their DNA is stained with heavy isotopes, and will ''maintain'' these stained strands UNTIL the environment changes. What they did is they used a light isotope, N-14 (or simply Nitrogen). What that means is that the bacteria had to adjust to this NEW environment, by ''taking up'' the N14 (so the bacteria are like: oh, I used to be in a heavy environment, better pick up the light environment too so I can adjust). These bacteria then have combinations of heavy stained strands(lets call it A) and light stained strands (lets call it B). Again, in normal environment, it keeps making AA. AA opens up, replicates, and makes AA again. Why? There is only A available. So, AA splits, and each A ''takes up'' another A. Now, let's add B into the system. AA, replicates, and you suddenly get AB because the bacteria ''adapts'' to the new environment. In other words, one A separates from the other A, and EACH of these ''take up'' a B. This is why we get this combination of AB AB. Now, do one more replication (of AB and AB), split each AB apart and what happens is that Bs will ''move in'' because the bacteria is still in that light environment, hence only Bs keep moving in. So we get: AB, BB, BB, AB (50:50 ratio, semi-conservative) And now, they wanted to see these changes by using a centrifuge. What this means, is that heavy ''things'' will move to the bottom, and light ''things'' will stay on top. So, in Generation 0 (where we only have heavy stains, A) shows that we get a band on the bottom (BECAUSE HEAVY, right?). In generation 1 (meaning we do replication), we get a combination, AB AB because we put these bacteria in a different environment (as mentioned before). We see one band that shows the N14/N15 combination, which is a little bit higher than the N15 band in Generation 0. Still not answering which model it is (either semi-conservative or dispersive can do that). In generation 2, we get AB BB BB AB, so aha! A 50:50 ratio. This shows us that this is semi-conservative. We see 2 bands: A N14/N15 band (because AB presence) and an N14 band (because BB presence.) Long, hope that helps (kind of).
JuggernautKnight Thank you so much. It did help me get my head around it a lot more! You explained it really well. 'Simple language' is what I needed :)
I'm sorry I have to correct you. You said that Watson and Crick figured out the shape of the DNA strand, but it was actually Rosalind Franklin who discovered that...
Ananya Ananth Watson and Crick gave the Double Helix model of DNA in 1953.They Used the X-ray diffraction data by Wilkins and Franclin.Later went onto win the Nobel prize in 1963.
Hey Maurice Wilkins and Rosalind Franklin doesn't figured out the shape of dna it was actually Watson -crick who discovered the shape of dna by using data of Wilkins Franklin experiment
@@VaibhavbBv Yes, Watson and Crick figured out the model with Rosalind's notes, which they essentially stole. The notes Rosalind was writing shows that she had the model practically figured out. They wrongfully used her without giving her any credit, and she passed away before she could receive any rewards of her own. Please understand the history before defending Watson and Crick
@Ashley L N14 was the tag on the original DNA strand. When it was mixed with the DNA tagged N15 it could still continue the replication because the N15 tagged nucleotides were still corresponding nucleotides, the N15 doesn't affect its ability to bind to the original DNA. As for the ratio of the N14 decreasing, its because there was only 2 single strands of DNA tagged N14. When the replicatio happens, the N15 nucleotides are the only nucleotides available for replication to continue hence more N15 strands are being made and so the ratio of N14 to N15 will slowly get larger as there are wayyy more N15 tagged strands than N14 tagged strands over time. Hope that helps xx
Science is magical, especially when we have people like you to guide us through every step of the way❤️ helpful video. I can't fathom how grateful I am. Hope you give us more helpful videos❤️❤️
Can you please site your resources because I always watch your videos to help me get a base for further research i'm doing in science however I cannot further the research as effectively because I do not know where you are getting your information from.
thanks for the video but just unsure about one thing, after the 88% to 12% in the end why did you say "if we keep going it will eventually drop off to all nitrogen" 😊 because the two N15 strands will always be there through the generations so it'll never be 100% N14 will it? please let me know thanks
through centrifugation, It is a process where the contents are spun at a very high velocity (45,000 revolutions in 20 hours) and thus separated. The heavy nitrogen is marked with a fluorescent dye and thus can be seen as the denser part of the solution. 3 years late but hoped that helped
Me : going to call my teacher to explain me this topic while seeing yt has none good vids on this Me sees Bozeman’s vid in this topic : cancels the call
thx so much! i have a question though: how many generations are needed in order to make sure that the DNA replication is semiconsrvative and not one of the others? is 1 generation enough? thx again
Yes and no. In the first generation you can discard the hypothesis "Conservative" because you will have 50% DNA in the "top" of the test tube (N14) and 50% in the bottom (N15). In the other hypothesis, "Dispersive", you have to do it more times because it is the chance that the original DNA divides itself in 2 equal segments, so you will have 2 chains of hybrid DNA with the same weight. Due that fact, you need to wait the second generation, cause then, anyways you had 2 equal chains of DNA in the first generation, you would see that in every next generation you will have more and more chains disperses in the test tube, it wouldnt have a pattern, it would be totally aleatory because every chain would have a different weight. (I hope you can understand me because i'm still learning english and i don't know if i have written correctly)
10 years later and this is still helpful ty
my final exam is tomorrow ... you were really helpful Mr.Andersen .. and our proffesor he's from Cambridge and only believe in the explain & mention & show & draw questions not a single mcq or t&f or even complete in the tests ..
but i got he's attention on the midterms , he said you the only student that got an 96% on his exam , really your videos helped me a lot , thanks
let's hope for the best in the final ..
how did it end?
i got an A .. :)
Doode malood nice :) good luck in your future.
thank you very much , you too man , that day in the exam as i expected all the questions were short answers and i let my imagination flow and that end up very well , good luck
What? Your grammar is atrocious
Loooooool it took me almost an hour to understand it from my books and i still didnt get it.. and now it took me 5 min just by watching this video and everything is clear 😅😅 thx 👍👍
same here bruw
@@earnitdamit961 bruv
True dat
Thank you soooo much. I am doing A level biology and this has really helped me!
Thank you! I was panicking because I have a test in less than 2 days about this. Thank you so much for helping me understand this experiment. The simulation helped a lot.
I've seen this explained a lot of different ways, but this is a nice and concise way of doing it. Answering "What does that mean?" is super important. So is using scientific language for your explanation, prompting students to look it up.
incredibly useful for my final genetics exam. Thanks a lot!
GARH! End of semester molecular genetics exam for uni tomorrow and you've just saved my life! Thank you.
I tried to understand this from my teacher 3 times and I couldn't. And once from you has done wonders for me. Thank you!
OMG YOU ARE A LIFE SAVER
U literally saved me by ur concise and clear language. It does explain everything
Great Video! I love your voice and the calm way you explain everything!
Takes you 4min to clearly explain this. Took my prof 45min to just confuse the hell out of me. Thank you!!!
THANK YOU SO MUCH! So clear and such a relief for understanding these complicated topics!!
you the best at everything. I come to watch your videos for biology, and chemistry. thanks a lot. we appreciate your work.
He explained it better than my professor, thank you!
THANK YOU!!! You were the only person to explain this experiment to me, so Thank you!
you explain so well, every video of you is so good
Mr Anderson actually explained it so nicely here no other channel made me understand it earlier!
Thank you so much! You have cleared my doubts on why nitrogen is used!
Very clear presentation, thanks for that
Wow i really liked ur explanation! It was so easy to understand and yet gave all the information i needed!
Its 2021 and this boomer is still helpinggg
I am MSc plant breeding student I have an exam advanced genetics, these video help me a lot
Thanks a lot. This really helped! Please keep making such videos on A level biology.
Honestly I can still Not get my head around this experiment! I've looked on nearly every website+ videos+ text books and I still don't get it. How does it show semi-conservative replication and why did they use bacteria?
Well, this is going to be a very long explanation, but I hope this weird, simplified ''idea'' helps you out:
Bacteria is one of the model organisms Geneticists and Cell Biologists use (along with Drosophila, Yeast, etc., these are quick and efficient). We do not want to experiment on our kind.
Anyway, this shows the semi-conservative replication because as he stated, bacteria are grown in an isotope that is heavy. So we give bacteria an environment they can adjust to, where they feel good. So they will undergo normal replication, whereas all the DNA is stained with the heavy isotope.
So, in this adjusted environment, their DNA is stained with heavy isotopes, and will ''maintain'' these stained strands UNTIL the environment changes. What they did is they used a light isotope, N-14 (or simply Nitrogen).
What that means is that the bacteria had to adjust to this NEW environment, by ''taking up'' the N14 (so the bacteria are like: oh, I used to be in a heavy environment, better pick up the light environment too so I can adjust). These bacteria then have combinations of heavy stained strands(lets call it A) and light stained strands (lets call it B).
Again, in normal environment, it keeps making AA. AA opens up, replicates, and makes AA again. Why? There is only A available. So, AA splits, and each A ''takes up'' another A.
Now, let's add B into the system. AA, replicates, and you suddenly get AB because the bacteria ''adapts'' to the new environment. In other words, one A separates from the other A, and EACH of these ''take up'' a B. This is why we get this combination of AB AB. Now, do one more replication (of AB and AB), split each AB apart and what happens is that Bs will ''move in'' because the bacteria is still in that light environment, hence only Bs keep moving in. So we get: AB, BB, BB, AB (50:50 ratio, semi-conservative)
And now, they wanted to see these changes by using a centrifuge. What this means, is that heavy ''things'' will move to the bottom, and light ''things'' will stay on top.
So, in Generation 0 (where we only have heavy stains, A) shows that we get a band on the bottom (BECAUSE HEAVY, right?).
In generation 1 (meaning we do replication), we get a combination, AB AB because we put these bacteria in a different environment (as mentioned before). We see one band that shows the N14/N15 combination, which is a little bit higher than the N15 band in Generation 0.
Still not answering which model it is (either semi-conservative or dispersive can do that).
In generation 2, we get AB BB BB AB, so aha! A 50:50 ratio. This shows us that this is semi-conservative. We see 2 bands: A N14/N15 band (because AB presence) and an N14 band (because BB presence.)
Long, hope that helps (kind of).
Cam S b
JuggernautKnight Thank you so much. It did help me get my head around it a lot more! You explained it really well. 'Simple language' is what I needed :)
Glad you understood it!
+JuggernautKnight omg crying thank u for the superb explaination! im really thankful.
my friend is from bozeman! love the connections in our world. Her name is minna gomp. Love it!
lmao
I'm sorry I have to correct you. You said that Watson and Crick figured out the shape of the DNA strand, but it was actually Rosalind Franklin who discovered that...
Ananya Ananth
Watson and Crick gave the Double Helix model of DNA in 1953.They Used the X-ray diffraction data by Wilkins and Franclin.Later went onto win the Nobel prize in 1963.
Hey Maurice Wilkins and Rosalind Franklin doesn't figured out the shape of dna it was actually Watson -crick who discovered the shape of dna by using data of Wilkins Franklin experiment
@@VaibhavbBv Yes, Watson and Crick figured out the model with Rosalind's notes, which they essentially stole. The notes Rosalind was writing shows that she had the model practically figured out. They wrongfully used her without giving her any credit, and she passed away before she could receive any rewards of her own. Please understand the history before defending Watson and Crick
Sorry if I was wrong
The best explanation I could find on this topic thank you 👌
@Ashley L N14 was the tag on the original DNA strand. When it was mixed with the DNA tagged N15 it could still continue the replication because the N15 tagged nucleotides were still corresponding nucleotides, the N15 doesn't affect its ability to bind to the original DNA. As for the ratio of the N14 decreasing, its because there was only 2 single strands of DNA tagged N14. When the replicatio happens, the N15 nucleotides are the only nucleotides available for replication to continue hence more N15 strands are being made and so the ratio of N14 to N15 will slowly get larger as there are wayyy more N15 tagged strands than N14 tagged strands over time.
Hope that helps xx
@Ashley L no worries xx
Thank you for this Video. I was looking for a simple answer to my school homework. I'm from Germany and even I understood the principle now.
Heartiest thanks with great satisfaction
You are explaining better than my teacher.
omg thank you so much. I didn't understand it a 100% from my books but this made it very clear- Thank you!
This is very helpful. Thanks Mr Andersen
This is the only video on RUclips that describes this well :D
Thank you Mr. Anderson!
OMG you just saved my life!! Thank you that was so helpful! You are amazing!
This video is a Godsend! Thanks you.
Yahweh sent
BEST EXPLANATION EVER!
REALLY NEEDED THIS!!
Best teacher in the whole world!!
The most clear and helpful viedo about expirment thanks a lot
Excellent explanation!!!
Thank you for this you make the understanding easier!
Thank you so much. It's so clear to me, now.
Really good and useful explanation. Thanks!
You just saved me one day :) Thanks a lot 🌟
Super great explanation better than my professor!
Amazing video for a level bio
Thank you, keep doing what you do!
Thank you so much, this was an excellent explanation!
Will let you know about my exam! Thanks a lot
Thank you so much! This is super helpful!
such an easy and clear video of the experiment, thank u so much:)
I understood through a 4 minute video about a concept I couldnt understand in 12 years of my education lol
Thanks aa lot! An amazing explanation!
Consise and informative. Thank you
Very good study material! Thank you so much!
Thank you ,Clearly explained.does this means that ecoli can synthesise isotopes of atoms too?
Best video for this experiment!
This is incredibly helpful
Thank you so much ❤
what does dna with N-15 mean? so the ecoli that grew in N-15 has nitrogen-15 in its nucleotide (more specifically base pairs) right?
Science is magical, especially when we have people like you to guide us through every step of the way❤️ helpful video. I can't fathom how grateful I am. Hope you give us more helpful videos❤️❤️
Thanks! This was very helpful.
their are no good videos in German on this but this was really easy to understand thanks!!
Thank you this is very insightful.
You are an actual science babe! Thank you!!
great video! very well explained!
The clearest video
omg thank you so much, best explanation
This is great! You can really well explain
Mr. Andersen u rock🥂
Thank you so much.. this was very helpful
TYSM IT MAKES SO MUCH SENSE NOW! :D
The only thing which i dont understand is :
Where do the newly synthesized strands come from ?
Probably don't need this anymore lol, but free-floating nucleotides
thanks mann its was really too good thank you
Awesome explanation!
Can you please site your resources because I always watch your videos to help me get a base for further research i'm doing in science however I cannot further the research as effectively because I do not know where you are getting your information from.
I really appreciate this.
sir u r d best :D:D :D :D u r just too good...nw i understand evrythng...n m sure it will help in my tmrw's test !! thanq so much
Yeah! I love Mr.Anderson as well! ^_^
He has helped me a lot! Esp that molecular inheritance wala chap! :')
same here!!
thanks for the video but just unsure about one thing, after the 88% to 12% in the end why did you say "if we keep going it will eventually drop off to all nitrogen" 😊 because the two N15 strands will always be there through the generations so it'll never be 100% N14 will it? please let me know thanks
Zaid Shah yeah i was wondering the same as well
how did he isolate the heavy nitrogen from the nitrogen?
through centrifugation, It is a process where the contents are spun at a very high velocity (45,000 revolutions in 20 hours) and thus separated. The heavy nitrogen is marked with a fluorescent dye and thus can be seen as the denser part of the solution.
3 years late but hoped that helped
Greetz from Germany! Thank you ! :)
Great explanation, thank you very much for this video!
awesome explanation
if they're both in equal amounts why then they dont replicate equally, why the n14 dominates the replication?
Because it's being grown in the light n14 nitrogen
Thank you so much!
thank you for this animation its amazing
Thank you so much because of you I understand now!!!!
This was very helpful! Thanks!!!
thanks. that was very helpful!
thank you very helpful!!
Me : going to call my teacher to explain me this topic while seeing yt has none good vids on this
Me sees Bozeman’s vid in this topic : cancels the call
Thanks a lot this helped so much..
great explanation,!
thx so much!
i have a question though: how many generations are needed in order to make sure that the DNA replication is semiconsrvative and not one of the others? is 1 generation enough?
thx again
Yes and no. In the first generation you can discard the hypothesis "Conservative" because you will have 50% DNA in the "top" of the test tube (N14) and 50% in the bottom (N15). In the other hypothesis, "Dispersive", you have to do it more times because it is the chance that the original DNA divides itself in 2 equal segments, so you will have 2 chains of hybrid DNA with the same weight. Due that fact, you need to wait the second generation, cause then, anyways you had 2 equal chains of DNA in the first generation, you would see that in every next generation you will have more and more chains disperses in the test tube, it wouldnt have a pattern, it would be totally aleatory because every chain would have a different weight. (I hope you can understand me because i'm still learning english and i don't know if i have written correctly)
I don’t understand how more light strands were produced
Thank you so much 💓
Best explained👍👌👌👌
this is so confusing,