Dna

[Mstoothlady2012]

Someone already posted this question before and klutzy gave good explanation but I still don't understand. What is the key word we are looking for in order to differentiate between these two questions? Also DNA molecule = double helix of DNA right?

If a strand of DNA underwent four rounds of replication, what percentage of the total DNA present would be comprised of original DNA molecule?

Consider a sample of DNA that undergoes four rounds of replication. What percent of DNA produced contains part of the original-stranded DNA?

Thanks!

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[250rsavage]

is both answers 6.25%

 

[Andrew324]

Yeah I dont know what the difference is. Are these two questions somewhere I could look up and see how the answers differ? Like destroyer, cliffs, kaplan?

 

[osimsDDS]

Someone already posted this question before and klutzy gave good explanation but I still don't understand. What is the key word we are looking for in order to differentiate between these two questions? Also DNA molecule = double helix of DNA right?

If a strand of DNA underwent four rounds of replication, what percentage of the total DNA present would be comprised of original DNA molecule?

Consider a sample of DNA that undergoes four rounds of replication. What percent of DNA produced contains part of the original-stranded DNA?

Thanks!

OHHH i think i get it!!! is the first one 6.25% and the second one 12.5%???

 

[Albuterol]

thats what i got too...i did it so a strand of DNA was just 1 strand and replicated that 4 times

l-->ll--> ll ll--->ll ll ll ll--->ll ll ll ll ll ll ll ll 1strand/16 strands=.0625

and for the second one i thought of a sample of DNA as a double stranded molecule and did pretty much the same thing except started with 2 strands and came up with 2strands/32strands= .0625

are these answers right?

 

[Albuterol]

haha u guys are quick w/the replies...already so many before i finished typing my post.

 

[xDent09]

the way to do it is like this,
1 replication= 50%
2 replications is = 25%
3 "= 12.5%
4 "= 6.25%

 

[250rsavage]

OHHH i think i get it!!! is the first one 6.25% and the second one 12.5%???

What your thinking behind the 12.5% osims????

 

[osimsDDS]

NVM i go with my gut instinct

 

[Andrew324]

but the first one asks for what Percentage of the total DNA.

MsToothylady2012 are these questions somewhere we can look up?

 

[Albuterol]

http://forums.studentdoctor.net/showthread.php?t=543161&highlight=DNA+replication

old thread with explanation and it has a link to another thread w/more explanations.

 

[250rsavage]

I am actually gonna change my answer:

1) 12.5%
2) 6.25%

My reasoning is because the first one asks for total DNA and the second you just divide the total by 2 because it asks for how much contains...

II
II II
II II II II
II II II II II II II II
1/8 is 12.5

and the second one is:
100 --50 -- 25 -- 12.5 -- 6.25

so this is what you are saying??

 

[Andrew324]

thanks Albuterol

This one has the quetions again.

For some reason when I read these they made more sense.
http://forums.studentdoctor.net/showthread.php?t=540918&highlight=Replication

 

[osimsDDS]

Someone already posted this question before and klutzy gave good explanation but I still don't understand. What is the key word we are looking for in order to differentiate between these two questions? Also DNA molecule = double helix of DNA right?

If a strand of DNA underwent four rounds of replication, what percentage of the total DNA present would be comprised of original DNA molecule?

Consider a sample of DNA that undergoes four rounds of replication. What percent of DNA produced contains part of the original-stranded DNA?

Thanks!

Ok i think i understand this now let me explain:

when they say the total DNA they mean strand for strand and when they say DNA produced they mean every DNA which consists of 2 strands...so total DNA strand for strand would be out of 32 and DNA produced (every 2 strands) would be 16 because for every 2 strands we have 1 DNA...so basically 2/16= 12.5% and 2/32= 6.25%

So second one should be 12.5% and first should be 6.25%

 

[Mstoothlady2012]

sorry for the delayed response..

1st one is from kaplan subject test # 5 Q 3 <--- 6.25%
2nd one is from destroyer - # 237 <--- 12.5%

How????????? Every1 gave different answers. only osims got it right but you didn't explain why? klutzy where r u?????? :-(

 

[Mstoothlady2012]

Ok i think i understand this now let me explain:

when they say the total DNA they mean strand for strand and when they say DNA produced they mean every DNA which consists of 2 strands...so total DNA strand for strand would be out of 32 and DNA produced (every 2 strands) would be 16 because for every 2 strands we have 1 DNA...so basically 2/16= 12.5% and 2/32= 6.25%

So second one should be 12.5% and first should be 6.25%

still dont understand.....

 

[250rsavage]

yeah I had them backwards, Dr green explanation is great.

Mstooth, if it has total then they are talking about strands, at least that's how I'm reading it.

 

[osimsDDS]

yeah I had them backwards, Dr green explanation is great

haha yea thats what i used to understand it

 

[osimsDDS]

still dont understand.....

check out Dr. green's explanation its pretty nice with drawing and everything!!! haha

 

[Mstoothlady2012]

check out Dr. green's explanation its pretty nice with drawing and everything!!! haha

yea i can totally answer the question right if it had said something like...

If a DNA molecule underwent 4 round of replication what percent of strands would have the original DNA? 2/32 = 6.25

If a DNA molecule underwent 4 round of replication what percent of DNA contains original DNA? 2/16 = 12.5

But the questions aren't these clear...nowhere in the question it differentiate if we are looking for the # of strands or # of DNA molecule at the end. Only at the beginning of question 1 they use word strand but that doesn't even indicate anything.

 

[osimsDDS]

yea i can totally answer the question right if it had said something like...

If a DNA molecule underwent 4 round of replication what percent of strands would have the original DNA? 2/32 = 6.25

If a DNA molecule underwent 4 round of replication what percent of DNA contains original DNA? 2/16 = 12.5

But the questions aren't these clear...nowhere in the question it differentiate if we are looking for the # of strands or # of DNA molecule at the end. Only at the beginning of question 1 they use word strand but that doesn't even indicate anything.

i know i find it pretty ridiculous...but wut can we do

 

[Andrew324]

i know i find it pretty ridiculous...but wut can we do

Hope the real test is more clear