DAT Destroyer Bio #325 (2011 version)

[DentistDMD]

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It is my understanding that four rounds of DNA replication yield 32 total strands, 2 of which stem from the original DNA strands. Am I correct on this? If so, wouldn't the answer to #325 be 2/32 = 6.25%? I'd appreciate any input on this. Thanks.

 

[FROGGBUSTER]

You get the concepts, you're just reading it incorrectly, like I did when I did this problem lol.

There are 32 strands at the end, 2 of which are of the original DNA. But those 2 strand are in separate double-stranded DNA. The question is asking about "what percent of the double-stranded DNA contains part of the original-stranded DNA."

There are 16 double-stranded DNA strand at the end, 2 of which consist of original DNA. 2/16 = 1/8 = 12.5%.

It's a dumb question, lols.

 

[wired202808]

You get the concepts, you're just reading it incorrectly, like I did when I did this problem lol.

There are 32 strands at the end, 2 of which are of the original DNA. But those 2 strand are in separate double-stranded DNA. The question is asking about "what percent of the double-stranded DNA contains part of the original-stranded DNA."

There are 16 double-stranded DNA strand at the end, 2 of which consist of original DNA. 2/16 = 1/8 = 12.5%.

It's a dumb question, lols.

Actually its a good question that can be asked on the real DAT so no point in knocking in, better to understand that in this sort of problem you would use 2 as a base. Meanwhile in other problems you would use 0.5 to the power of replications i.e. 4 replications would be 0.5^4 = % of remaining original DNA

 

[FROGGBUSTER]

This is a type of question that everyone would get wrong on the DAT due to misreads, so it would never appear.

 

[LetsGo2DSchool]

Nice explanation Frogster. I was wondering about the logic as I misread it too.

 

[Bis-GMA111]

you keep going down by a factor of 1/2 (multiply each round by 1/2)

1 round-->1/2 of original
2 rounds-->1/4
3 rounds-->1/8
4 rounds-->1/16