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DNA bases percentage ??

Hi guys,

I am not really sure on how to answer these type of questions, i knw there would be a formula/method to calculate them,

When the base composition of DNA from 'an organism' was determined, 16% of the bases were found to be adenine-
what is the percentage of cytosine?
what is the entire % base composition (% of A, T,C, G) of the DNA?

any ideas

Reply 1

Ezraeil

15

Gamewizard

Hi guys,

I am not really sure on how to answer these type of questions, i knw there would be a formula/method to calculate them,

When the base composition of DNA from 'an organism' was determined, 16% of the bases were found to be adenine-
what is the percentage of cytosine?
what is the entire % base composition (% of A, T,C, G) of the DNA?

any ideas

Hey

Think about it from a mathematical point of view:

We know Adenine pairs with Thymine,and Cytosine pairs with Guanine.So there must be equal amounts of A and T,and equal amounts of C and G.

16% adenine means 16% thymine=32%

We have 68% left...since there are equal amounts of C and G,68 will be divided by 2,giving 34% of Cytosine and Guanine each.

So A=16%,T=16%,C=34% and G=34%.

:biggrin:

Reply 2

CJ89

A ~ 16%
T ~ 16%

C ~ 34%
G ~ 34%

Reply 3

cd.thomson

SyedT

Hey

Think about it from a mathematical point of view:

We know Adenine pairs with Thymine,and Cytosine pairs with Guanine.So there must be equal amounts of A and T,and equal amounts of C and G.

16% adenine means 16% thymine=32%

We have 68% left...since there are equal amounts of C and G,68 will be divided by 2,giving 34% of Cytosine and Guanine each.

So A=16%,T=16%,C=34% and G=34%.

:biggrin:

+1, completely right and well explained

Reply 4

Gamewizard

OP

2

SyedT

Hey

Think about it from a mathematical point of view:

We know Adenine pairs with Thymine,and Cytosine pairs with Guanine.So there must be equal amounts of A and T,and equal amounts of C and G.

16% adenine means 16% thymine=32%

We have 68% left...since there are equal amounts of C and G,68 will be divided by 2,giving 34% of Cytosine and Guanine each.

So A=16%,T=16%,C=34% and G=34%.

:biggrin:

Thank you, I understand it now :smile:

Reply 5

Kingafy

I have this DNA problem solving coursework tomorrow, and our teacher says its going to be calculation based. I understand that base pairing is complementary and that the pairs A-T, C-G equal each other and to 100%. However, she has asked us why in some cases they might not equal to 100% percent or equal to one another. I have thought about mutations, intron, exons & stop codons but she has said they are incorrect. any help?

Reply 6

Eloades11

17

Original post by Kingafy

I have this DNA problem solving coursework tomorrow, and our teacher says its going to be calculation based. I understand that base pairing is complementary and that the pairs A-T, C-G equal each other and to 100%. However, she has asked us why in some cases they might not equal to 100% percent or equal to one another. I have thought about mutations, intron, exons & stop codons but she has said they are incorrect. any help?

Not equal to 100% could include mutations, such as mismatch mutations or pyrimidine dimers. There's also the assumption the DNA in question is double stranded. It would not be 100% complementary if the DNA was single stranded.

Reply 7

Era Derjaj

1

Hello,Can you help me about percentage of adenine nukleotide. How is the percentage of adenine nucleotide in DNA, if we know that the percentage of cytosine is 22%? Waiting for your answer. Thank You very much.

Reply 8

Eloades11

17

Original post by Era Derjaj

Hello,Can you help me about percentage of adenine nukleotide. How is the percentage of adenine nucleotide in DNA, if we know that the percentage of cytosine is 22%? Waiting for your answer. Thank You very much.

So you know that adenine matches with thymine, meaning they would have the same percentage. Also, guanine matches with cytosine meaning those two have the same percentage. All of these percentages must add to 100%, so if cytosine is 22, guanine is also 22. This would leave 56% to adenine and thymine.

Reply 9

QuentinM

17

Original post by Gamewizard

Hi guys,

I am not really sure on how to answer these type of questions, i knw there would be a formula/method to calculate them,

When the base composition of DNA from 'an organism' was determined, 16% of the bases were found to be adenine-
what is the percentage of cytosine?
what is the entire % base composition (% of A, T,C, G) of the DNA?

any ideas

Worth noting that whilst what everyone said was technically right, it assumes "complimentary base pairing" in whatever organism it was. This isn't always the case, in some organisms there is enough single stranded DNA to unpaid the numbers associated with complementary bases.

However if there isn't complementary base pairing in whatever organism this is, you'll see why you can't answer the question :smile:

So just a heads up, don't assume questions like this will ALWAYS involve complementary base pairing.

Reply 10

Aura karma

2

Do you know how many permutations of DNA sequences can be formed in a helical turn ?

DNA bases percentage ??

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