Nucleotides are linked by...

[GoVegan]

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The Kaplan course book's Bio Chapt. 3 (Genetics) review problem #9 is the following...

Nucleotides are linked by
A. hydrogen bonds
B. phosphodiester bonds
C. covalent bonds
D. van der Waals bonds

I thought the answer was B but according to the solutions the answer is A because "Nucleotides are linked by hydrogen bonds. A always binds to T with two hydrogen bonds while C and G bind with three hydrogen bonds. Note that phosphodiester bonds are covalent bonds."

Isn't this answer just explaining how the bases bond together, not the nucleotides? I understand that phosphodiester bonds are covalent, but they are the specific type of covalent bonds between nucleotides. If the question were to be taken as talking about RNA, which doesn't have H-bonds between bases but has nucleotides, wouldn't the answer have to be B?

 

[Double Bonded]

The Kaplan course book's Bio Chapt. 3 (Genetics) review problem #9 is the following...

Nucleotides are linked by
A. hydrogen bonds
B. phosphodiester bonds
C. covalent bonds
D. van der Waals bonds

I thought the answer was B but according to the solutions the answer is A because "Nucleotides are linked by hydrogen bonds. A always binds to T with two hydrogen bonds while C and G bind with three hydrogen bonds. Note that phosphodiester bonds are covalent bonds."

Isn't this answer just explaining how the bases bond together, not the nucleotides? I understand that phosphodiester bonds are covalent, but they are the specific type of covalent bonds between nucleotides. If the question were to be taken as talking about RNA, which doesn't have H-bonds between bases but has nucleotides, wouldn't the answer have to be B?

I think they meant to trick you

Nucleosides are linked together by p-bonds
Nucleotides are lined together by h-bonds

 

[GoVegan]

I think they meant to trick you

Nucleosides are linked together by p-bonds
Nucleotides are lined together by h-bonds

But a nucleoside is sugar + base. There isn't a phosphate to form a phosphodiester bond.

 

[Double Bonded]

But a nucleoside is sugar + base. There isn't a phosphate to form a phosphodiester bond.

You're right. I don't know.


lol 😛

 

[FROGGBUSTER]

i'd agree with you, linkage usually implies covalent bonding. poorly worded question.

 

[Kobebucsfan]

that same Q is also on Topscore and they say Hydrogen bonding 😕

 

[Kobebucsfan]

i guess the answer is hydrogen bonding:

http://answers.yahoo.com/question/i...rf2QFqYazKIX;_ylv=3?qid=20110611152550AAzoB4q




then wth is phosphodiester bond ?

 

[Troyvdg]

lol. I was wondering the same thing when I came across this question.
maybe phosphodiesters link the sugars together and H-bonds link the nucleotides together?

 

[bharat008]

I was thinking it was phosphodiester bond too..
If you think about the structure though you have DEOXYRIBOSE sugar where the Phosphate is attached to 5' carbon which attaches to the next sugar's 3' carbon. This is phosphodiester bond. It grows 5' to 3'

The bases or nucleotides are attached at the 1' carbon ( i think) which attaches to other nucleotides on the anti-parallel DNA strand using H Bond..

I hope this would make sense.. I just made it up and it looks right to me..😀

 

[yappy]

I dont like this question. My understanding is that a nucleotide is base+sugar+phosphate. Therefore, the nuceotide is connected via a phosphodiester bond building the sugar-phosphate backbone. This allows contiguous nucleotides to be connected together.

If the question were to ask how are nitrogenous bases linked - then I would say h-bonding. G:C, A:T

 

[GoVegan]

I dont like this question. My understanding is that a nucleotide is base+sugar+phosphate. Therefore, the nuceotide is connected via a phosphodiester bond building the sugar-phosphate backbone. This allows contiguous nucleotides to be connected together.

If the question were to ask how are nitrogenous bases linked - then I would say h-bonding. G:C, A:T

Exactly. Continuing on this train of thought, the question could be talking about DNA or RNA (since it doesn't specify and they both have nucleotides). Therefore, the answer can't be H-bonds since they don't occur between nucleotides in RNA.

If the question asked "Nucleotides in adjacent DNA strands are linked by...", then H-bonds would make sense.

I don't know. This question is bothering me way more than it should. 😡

 

[Strag]

Ok. So phosphodiester bonds link nucleotides of the same strand. Hydrogen bond holds nucleotides that are complementary to each other (forming the double helix).

The question is poorly worded. Hydrogen bonds the bases of the nucleotides, but phosphodiester bonds like phosphate group of one nucleotide to the carbon ring of the next nucleotide.