anybody knows how to get to this answer??

[sania]

---

Members do not see this ad.

QUE) one strand of DNA helix is 20 % A, 30% T and 40% C, what is the %age of C on the other strand?

1)10
2)20
3)50
4)80
5)90

 

[make you smile]

one strand of DNA helix is 20 % A, 30% T and 40% C, what is the %age of C on the other strand?

1)10
2)20
3)50
4)80
5)90

The answer is 50%. A+G=T+C in DNA. 20+G=30+40,SO G=50. On the first thread if G=50 ,on the second thread C=50 as G and C pair with each other.

 

[Kash]

one strand of DNA helix is 20 % A, 30% T and 40% C, what is the %age of C on the other strand?

1)10
2)20
3)50
4)80
5)90

The answer is 50%. A+G=T+C in DNA. 20+G=30+40,SO G=50. On the first thread if G=50 ,on the second thread C=50 as G and C pair with each other.

I think thats correct... purines = pyrimidines

 

[dmddds]

i dont know but total percentage is a little weird... how is it that in one strand the total percentage is A=20% T=30% and C is 40 % so total percent is 90 and according to you G is 50 so out of 100 percent the total percentage of nucleotides is 140 % ????

simplest way to measure it is to add all the values and subtract it from 100 that would be the percentage of 4th. so 10% G now AT GC so G combines with C so the answer is 10%

 

[indiabds]

u r right .....
ans should be 10

i dont know but total percentage is a little weird... how is it that in one strand the total percentage is A=20% T=30% and C is 40 % so total percent is 90 and according to you G is 50 so out of 100 percent the total percentage of nucleotides is 140 % ????

simplest way to measure it is to add all the values and subtract it from 100 that would be the percentage of 4th. so 10% G now AT GC so G combines with C so the answer is 10%

 

[AlwaysImproving]

u r right .....
ans should be 10

Definitely 10%.

 

[nlax30]

simplest way to measure it is to add all the values and subtract it from 100 that would be the percentage of 4th. so 10% G now AT GC so G combines with C so the answer is 10%

👍

 

[make you smile]

i dont know but total percentage is a little weird... how is it that in one strand the total percentage is A=20% T=30% and C is 40 % so total percent is 90 and according to you G is 50 so out of 100 percent the total percentage of nucleotides is 140 % ????

simplest way to measure it is to add all the values and subtract it from 100 that would be the percentage of 4th. so 10% G now AT GC so G combines with C so the answer is 10%

The total % of purines and pyrimidines in one strand NEED NOT be 100%.The total % of purines and pyrimidines in total DNA needs to be 100%.For example a strand can be like AAGGGGGTTTTCAAA.The corresponding strand would be like TTCCCCCAAAAGTTT.Note that number of purines and pyrimidines on one strand is not equal but number of purines and pyrimidines is same when both threads are put together(total DNA).Hope this helps!

Sometimes the easiest way is not the correct way.🙂

 

[toothfairy482]

where is this question from? Just asking so we can check our source if we have an explanation and what the answer is. thanks!

 

[pb2007]

answer should be 10% only coz if A 20%,T 30%,C 40%,so G on this strand is 10% ,so on opposite strand G will pair up wit C,so th content of C on opposite strand should also be 10%,correct me if wrong

 

[firasoblast]

where is this question from? Just asking so we can check our source if we have an explanation and what the answer is. thanks!

It's either 99 or 02 paper. and I believe make you smile is right.

 

[Cindrella]

Definitely 10%.

Hey Always Improving ... U seem to have cracked the exam... Could you plz tell me the details of the exam for which u appeared and hw did u study etc...i'm totally unprepared and my exam is in another 6 months😱😕👎

 

[AlwaysImproving]

Hey Always Improving ... U seem to have cracked the exam... Could you plz tell me the details of the exam for which u appeared and hw did u study etc...i'm totally unprepared and my exam is in another 6 months😱😕👎

O man, I am sorry, I haven't taken the NBDE exam yet, I am still pre-dent.
I was able to answer that question bec/ I took genetics in undergrad.


But I wish you the best, you still have 6 months, that is plenty of time! GL

 

[lotexigeus]

answer should be 10% only coz if A 20%,T 30%,C 40%,so G on this strand is 10% ,so on opposite strand G will pair up wit C,so th content of C on opposite strand should also be 10%,correct me if wrong

ding ding ding

 

[voyager101]

where is this question from? Just asking so we can check our source if we have an explanation and what the answer is. thanks!

This explanation for this question is in Usml biochem lecture notes at the end of chapter 1.

 

[toothfairy482]

voyager can you please give explanation and right answeR? I dont have the questions at the end of my chapter because my notes are photocopies....thanks!

 

[La fea]

voyager can you please give explanation and right answeR? I dont have the questions at the end of my chapter because my notes are photocopies....thanks!

10% IMO

The q asks "one strand of DNA helix is 20 % A, 30% T and 40% C, what is the %age of C on the other strand?"

in strand 1, A+T+C= 20+30+40= 90 ie G= 10, for a total of 100%

Therefore in strand 2, since G pairs w/ C, the answer is 10%

Hope this helps

 

[toothfairy482]

voyager the question is not there!

 

[lotexigeus]

look one post above you. The explanation is right there, i promise.

 

[make you smile]

.

 

[nlax30]

Where does it say that A+G+C+T on one strand should be equal to 100%? It only says that A+G=C+T, number of purines should be equal to pyrimidines in total DNA.If you were to apply this formula to what you said 20+10=40+30,that's not right,isn't it?

I stand by what I said.Anyone with more knowledge on this can please contribute.

You're switching between thinking about 1 strand and thinking about both strands.

Just look at 1 one of the complimentary strands..... say there are 100 bases in total and 20% are A, 30% are T, and 40% are C. How many G's would there be in THAT PARTICULAR strand? 10. Out of the 100 bases 90 of them are either A, T, or C, so the other 10 should be G. So if 10 are G on this strand, then there must be 10 C on the other strand to pair.

You could actually go through and figure the percentage of A,T,C,G on BOTH strands and THEN you could apply A+G = C+T and it would work out.

 

[make you smile]

You're switching between thinking about 1 strand and thinking about both strands.

Just look at 1 one of the complimentary strands..... say there are 100 bases in total and 20% are A, 30% are T, and 40% are C. How many G's would there be in THAT PARTICULAR strand? 10. Out of the 100 bases 90 of them are either A, T, or C, so the other 10 should be G. So if 10 are G on this strand, then there must be 10 C on the other strand to pair.

You could actually go through and figure the percentage of A,T,C,G on BOTH strands and THEN you could apply A+G = C+T and it would work out.

Hey,I was JUST rethinking about what I wrote.That's exactly why I edited my post. I came to the same solution.The answer is 10%.

 

[make you smile]

There is a question on % of bases in packet K-bio-chemistry.The question goes like this.....

If the molar % of adenine is 22%,what is molar % of guanine in a given DNA sample?

Since it is a DNA sample,the four bases are A,G,C and T.The % of adenine is 22%.A pairs with T.So T is also 22%.The total % of C and G is 100-(22+22)=56 %.Since C pairs with G,they must be equal quantity.So guanine is 28%.One can check this with A+G=C+T.Hope this helps!

Btw,what I said in the second post in the thread is correct.The only thing is that this question has specific % of bases which are already given.I explained taking a hypothetical DNA strand. This is why I was confused. I hope everyone who gets this type question on the exam will be able to answer it correctly,after all this discussion.🙂