dna structure chemistry help
here is the question and answer: https://imgur.com/a/RnD88kB
why does the phosphate group have a negative charge? there is nothing explaining that in the textbook nor is there anything i can see in the question that gives this away
why does the phosphate group have a negative charge? there is nothing explaining that in the textbook nor is there anything i can see in the question that gives this away
Original post by _ks233
O normally makes 2 covalent bonds but on the phosphate one of the O is only bonded to one other atom so it is negative
the negative O is normally OH so why has it been deprotonated
Original post by onedance1
the negative O is normally OH so why has it been deprotonated
It's deprotonated because the PKa of the phosphate group is quite low, around 2, so is deprotonated at the relatively neutral pH we see inside the body. This is because at a pH below the pKa, the acid is protonated. At a pH above the pKa the acid is deprotonated.
If you don't know what I mean by PKa, have a look here, in the section "the acid dissociation constant" and "An introduction to pKa".
You should note that PKa isn't in every A-Level chemistry syllabus depending on your exam board, so you might not need to know this. If this is a biology question, you definitely won't need to know it and should simply memorise that there's one O-. You're asking the right questions, though!
(edited 3 years ago)
Original post by jm4761
It's deprotonated because the PKa of the phosphate group is quite low, around 2, so is deprotonated at the relatively neutral pH we see inside the body. This is because at a pH below the pKa, the acid is protonated. At a pH above the pKa the acid is deprotonated.
If you don't know what I mean by PKa, have a look here, in the section "the acid dissociation constant" and "An introduction to pKa".
You should note that PKa isn't in every A-Level chemistry syllabus depending on your exam board, so you might not need to know this. If this is a biology question, you definitely won't need to know it and should simply memorise that there's one O-. You're asking the right questions, though!
If you don't know what I mean by PKa, have a look here, in the section "the acid dissociation constant" and "An introduction to pKa".
You should note that PKa isn't in every A-Level chemistry syllabus depending on your exam board, so you might not need to know this. If this is a biology question, you definitely won't need to know it and should simply memorise that there's one O-. You're asking the right questions, though!
thank you, i do need to know about pKa im just confused because no where in my textbooks or lessons have i seen this O- on the phosphate group so how was i supposed to know
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