DNA sample replication

Started by Xo1991
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Xo1991

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This is referring to Bio #367 destroyer

Consider a sample of DNA that undergoes 4 rounds of replication. What % of the double stranded DNA produced contains part of the original-stranded DNA?

So, is starts off at 100%

100%------------>50%--------->25%------------12.5%
The answer they give is 12.5%, but isn't that only after 3 replications? Shouldn't the answer be 6.25%?

I've drawn it out several times and am still confused how the answer is 12.5%.
 
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Xo1991 said:
This is referring to Bio #367 destroyer

Consider a sample of DNA that undergoes 4 rounds of replication. What % of the double stranded DNA produced contains part of the original-stranded DNA?

So, is starts off at 100%

100%------------>50%--------->25%------------12.5%
The answer they give is 12.5%, but isn't that only after 3 replications? Shouldn't the answer be 6.25%?

I've drawn it out several times and am still confused how the answer is 12.5%.
Click to expand...

AA (1/1)
ABAB (2/2)
ACBCACBC (2/4)
ADCDBDCDADCDBDCD (2/8)
AEDECEDEBEDECEDEAEDECEDEBEDECEDE (2/16)
:idea:

Remember that in the first round of replication, both new strands will contain original DNA...it's so...semiconservative.
 
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It's not asking what % of the single DNA strands have origin DNA (which would be 2/32, or 6.25%). You have 32 strands to make 16 double stranded samples. There are 2/32 oringinal strands, but since they don't pair with each other but rather with new strands, 2/16 double stranded samples have some oringal DNA in them.
 
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athomas said:
It's not asking what % of the single DNA strands have origin DNA (which would be 2/32, or 6.25%). You have 32 strands to make 16 double stranded samples. There are 2/32 oringinal strands, but since they don't pair with each other but rather with new strands, 2/16 double stranded samples have some oringal DNA in them.
Click to expand...

what this guy said
 
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