What Three Things Form a Nucleotide

[jhinton]

Ok the question in the exam went like this

"What three REACTANTS undergo condensation reactions to form this nucleotide"

Many are saying the answer is a deoxyribose sugar, adenine, and phosphate.  Isn't phosphate the connecting link in the product, and shouldn't the REACTANT actually be phosphoric acid?  Thanks.

[thatricksta]

i wrote deoxyribose sugar, adenine and phosphate.. it looked like one of those questions that you are meant to pull from the databooklet

[jhinton]

Yes many people have said that, but according to the question, wouldnt phosphoric acid work too? Really wat Im asking is, is it phosphoric acid that reacts with the deoxyribose sugar to form the DNA backbone?

[peterle1]

Nope shouldn't be a phosphoric acid just a phosphate which will have a condensation reaction with dna to form the backbone

[tiktokcheekaboom]

SHOOT!!!!!!! I COMPLETELY FORGOT TO IDENTIFY THE BASE D:
I wrote nitrogenous base instead... is that definitely wrong?? T_T

[thatricksta]

SHOOT!!!!!!! I COMPLETELY FORGOT TO IDENTIFY THE BASE D:
I wrote nitrogenous base instead... is that definitely wrong?? T_T

add it to the stupid mistakes post.. coulda been worse, i wrote ethene when in my head i said ethanol, read over it twice as "ethanol" =/

[DisaFear]

add it to the stupid mistakes post.. coulda been worse, i wrote ethene when in my head i said ethanol, read over it twice as "ethanol" =/

I hope this isn't for the DNA question rofl

[jhinton]

In order for a condensation reaction to occur, a small byproduct must be made, such as H2O. The formula for phosphate is PO4(3-).  Phosphate will not be able to form water of any kind as it must also have a hydrogen somewhere. Also, in the diagram accompanying the question, the phosphate link was drawn with one attached OH group on it (usually we think of the phosphate link in DNA just have oxygens with negative charges). Phosphate does not have an OH group, so it couldnt be phosphate that reacts.

[ttn]

I wrote phosphate group, will that be that ok?

[stonecold]

Phosphate is fine.

At biological pH, phosphate does not really exist in the protonated form.

[jhinton]

do you think phosphoric acid will also be acepted, and in that case, orthophosphoric acid?

[Russ]

Orthophosphoric acid is completely unnecessary but is equivalent to phosphoric acid if you seriously wrote it

[vea]

What about if you wrote phosphate ion?

[jhinton]

I did write orthophosphoric acid =P My teacher always corrects us for some reason when we just say phosphoric acid, so I thought I was being extra "smart" lol

[pi]

I wrote: (like exactly what I wrote)
- Phosphate (dihydrogen orthophosphate)
- Deoxyribose sugar
- Adenine (nitrogenous base)

Hope that works


Don't think it was phosphoric acid btw