DNA vs RNA?

[sangria1986]

whats the difference between the two in terms of structure?

I know DNA is a 5 carbon sugar with 4 carbons and an oxygen in the ring...also its carbon 1'(is this right) is attached to a pyrimidine(AG) or purine (CT) and the 3 carbon is bound to an OH which becomes OP when binding to another nucleic acid. The 4 carbon is bound to the Oxygen as well as the 5 Carbon which is normally bound to 3 phosphates but becomes one phosphate in DNA.

Right so far? Also, GC triple bond, AT are double bonds...

what about RNA?

do we have to know anything about DNTP other than that its whats used to make DNA during replication or transcription? also, I know that the breaking of the two phosphate bonds off dNTP provide the energy for replication transcription correct?

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[Rabolisk]

Structurally, DNA is deoxyribose. Instead of OH, it only has H on carbon 2 C2 is bonded to two Hs instead of one OH and one H.

 

[Web]

DNA can have 3 phosphates or 1 phosphate depending on whether or not it has been charged (DNTP and all that), but that is not a difference between DNA and RNA. The difference between DNA and RNA is, as Rabolisk said, DNA has had the -OH on carbon 2 replaced with an -H. In basic conditions the -OH can be deprotonated leaving RNA vulnerable to a Lewis acid (and the phosphate might act as one, biochemistry was a few years ago, so its getting fuzzy).

GC has three hydrogen bonds and AT has two yes.

 

[sugarbabee0]

And i just got a question wrong on a practice test since i didn't know that A=U bonds (double bond) are weaker than A=T's double bond.

The above, and the fact that DNA has no -OH group (which can react w stuff), leads to DNA being more stable than a double stranded RNA.

 

[seraphkz]

By the way, purines are AG..Pyrimidines are CT.

 

[AcclratngCharge]

By the way, purines are AG..Pyrimidines are CT.

Fwiw: CUT-py, like piece of pie, that from a biochemistry teacher i had

 

[seraphkz]

Or All Girls are Pure



That's from a fellow SDNer haha

 

[Rabolisk]

Or All Girls are Pure



That's from a fellow SDNer haha

What is this I don't even..

 

[seraphkz]

Hahahah

 

[AcclratngCharge]

What is this I don't even..

You're joking right? Or you need to study some more.

I like it, now my base mnemonics are complete

 

[Rabolisk]

You're joking right? Or you need to study some more.

I like it, now my base mnemonics are complete

Yes, I feel that I need to study more. Can you help me?

 

[AcclratngCharge]

Yes, I feel that I need to study more. Can you help me?

No problem, answering questions on here helps me better understand/learn things

CUT py (Cytosine, Uracil, Thymidine are pyrimidines, which are the single ringed nitrogenous bases), they always bind to a purine...

All girls are Pure
Adenine and Guanine are purines (two ringed N-bases)

A2T, G3C = DNA (2, 3 are the numbers of hydrogen bonds holding the respective bases together) GC is essentially 1.5x stronger due to the extra hydrogen bond. Know that A:T and G:C are always in 1:1 ratio (unless there is a mutation or base pair mismatching which would be explained in a passage)

In RNA there is no T, it is replaced by Uracil
A2U, G3C is base pair matching in RNA

Definitely know for the MCAT:
Where is mRNA processed?
What is transcription/translation/replication?
Where are ribosome subunits assembled?
How is gene expression regulated?
What are the 3 types of RNA?
How do prokaryotes and eukaryotes differ?

If you can answer each of those (briefly, MCAT isn't detailed) you should be able to do well on MCAT DNA stuff. I would recommend EK Biology Manual. I have taken 2 biochem classes and would have been too detail-oriented on the MCAT but that book just tells you what to know, and has helped me so far.

 

[Rabolisk]

Actually there's one topic that's been bothering me... What is the difference between enthalpy and heat?

 

[AcclratngCharge]

Actually there's one topic that's been bothering me... What is the difference between enthalpy and heat?

That is one of the most difficult concepts on the MCAT, fortunately MCAT doesn't get too detailed. I don't feel real comfortable about this subject, but here is what I know from AAMCs

Know heat(q) is a type of energy transfer. Know the 3 types convection/conduction/radiation. Just don't think about these 3 when doing a heat of reaction problem. In physics, know what when friction warms something up, it is changing the internal energy by work, it is not heat (since heat requires 2 objects/systems be at different temperatures.)

Enthalpy. If there is no change in pressure during a reaction, which is usually the case on the MCAT, the change in enthalpy is the same as heat (because it is just the change in internal energy, since there is no PVwork). So to answer MCAT questions, they always say "heat of reaction" which is delta H.

For delta H know what the sign means. Exothermic vs. endothermic, and what types of reactions fall into each category (eg condensation is exothermic). For this delta H, H of reaction, what helps me best understand it is looking at energy graphs and heat curve graphs.

I don't feel confident, but the MCAT asks easy stuff like: In Rxn 3 of the purification of Zinc process as described in the passage, if delta H is negative, and delta S is positive, is the reaction spontaneous at 25C and 1 atm?