Biology Forums - Study Force

Part B - Experimental results: Banding pattern predictions for each model of replication
Meselson and Stahl designed an experiment that would allow them to discern whether DNA replication occurs in a dispersive, semiconservative, or conservative manner.
They started with E. coli that had been growing for many generations in medium containing 15N.
They then transferred the bacteria into medium containing only 14N, and allowed the bacteria to undergo two rounds of DNA replication.
After each round of replication, the scientists performed density-gradient centrifugation of the DNA.
The scientists reasoned that each of the three models would predict different DNA banding patterns after the two rounds of replication.
Can you identify the banding patterns predicted by each model after the first round of replication? (Then, in Part C, you will identify the banding patterns predicted after the second round of replication.)
Drag the test tubes to the appropriate locations in the table to show the banding patterns that each model predicts. Test tubes may be used once, more than once, or not at all.

Since you haven't provided a schematic, I really don't know where to drag the labels. I found a few good reads that might help you understand the question, though I'm severely limited to what I can do since a lot of information is missing.

I have attached the image that goes with this problem. I apologize that I couldn't paste the link like the other image from the other question. Thank you very much for the help!

It's not a problem, I do have the perfect image for you. Try to follow along, you should derive at the answer :angel:

Thank you very much for the image! I just want to make sure that I have the correct answers. I have trouble with diagrams like this, therefore if my answers are wrong could you explain why in order to help me understand the question better? I have attached the image with my answers.

that wasn't the correct answer... did you figure it out?

yeah i'm stuck too.. im on my last attempt and have 1 out of the 3 wrong

Here's how I see, though I'm not sure...

(https://biology-forums.com/gallery/43/6_15_12_21_9_12_08.gif) (https://biology-forums.com/index.php?action=gallery;sa=view&id=43882)

This is what I got

yup that was right!! finally

any ideas for this one? getting close to the due date! haha

Content hidden

Hi ekrieger,
for some reason I can't attach a picture in the msg you sent me but I'm going to attach it here. Were you talking about this question?

we must have different questions bc thats not it.. oh well, thanks so much for trying!!  :D

Hi again ekrieger,
Try this. Hope it helps  :)

omg thank you so much!! your awesome, i got it right :) i hate to be annoying but any chance you got this one too??

ekrieger,
hope this helps.

We only have one attempt also which is dumb because if we get it wrong we won't know the right answer

Queenhoa's answer was correct

(B)               [Dispersive]    [Semiconservative]  [Conservative]

1st replication: 14N/15N              14N/15N          14N/14N
                                                                        15N/15N


2nd Replication: 14N/15N           14N/14N            14N/14N
                                                14N/15N            15N/15N

for part C the answers are:

a) 14N/14N
     14N/15N

b) 14N/14N
     15N/15N

I just tried this on mastering biology and I got it right!:)

This is the right answer

This is the correct answer after 3 tries

hope this helps

Thanks, this problem gave me trouble to!

This one is correct  :)

Correct Answer:
Correct Answers, I just solved it:
1. 14N/15N (along middle dotted line)     

2.14N/15N (along middle dotted line)               

3. 14N/14N (along top dotted line) 15N/15N (along bottom dotted line)

Thank you so much! I was really stuck!

VERY NICE ILLUSTRATION

Thanks!

thank you!

thank you

thank you

Thank you! :)