Why can't adenine and cytosine pairs form?

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Homework Help Overview

The discussion revolves around the inability of adenine and cytosine to form stable pairs, focusing on the underlying reasons related to molecular bonding and structure. Participants explore the nature of hydrogen bonds and the significance of molecular shape in determining stability.

Discussion Character

  • Conceptual clarification, Assumption checking

Approaches and Questions Raised

  • Participants discuss the bond strength and stability of adenine and cytosine pairs, questioning why their shapes do not allow for effective hydrogen bonding. There are inquiries about the broader implications of molecular duplication and its importance in biological systems.

Discussion Status

Some participants have provided insights into the reasons behind the instability of adenine and cytosine pairs, while others have raised questions about the significance of molecular duplication. The discussion is exploring multiple interpretations of these concepts without reaching a consensus.

Contextual Notes

Participants are navigating assumptions about molecular interactions and the importance of replication in biological contexts, with varying perspectives on what constitutes "importance" in nature.

joejo
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hi I was curious Why can't adenine and cytosine pairs form? Like I know it doesn't happen but WHY?

thanks for your help guys and girls!
 
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joejo said:
hi I was curious Why can't adenine and cytosine pairs form? Like I know it doesn't happen but WHY?
It is not that they can't bond at all. It is just that the total bond strength is not very strong, so it is not stable. All bonds are hydrogen bonds, so to make a strong molecular bond there have to be many points of contact between points with opposite polarity. This will only occur if the shapes are complementary so that they fit together. The fact is that the shape of adenine and the shape of cytosine don't fit together very well. Thymine (or uracil in RNA) fit much better with adenine, providing many more points of hydrogen bonding and a much more stable bond.

AM
 
hey andrew,

thanks soo much its makes more sense now...because they are all constant at 2nm but then again there will be a lack of hydrogen bonding making the pair unstable...


my next ? is why is duplication important? is there any reason behind the importance of duplication/replication
 
joejo,

"is there any reason behind the importance of duplication/replication"

That depends on what makes something "improtant". Nature doesn't care one way or the other whether one of its processes involves the replication of extermely complex molecules. It just stumbled on to this system, and the result was living organisms (which it also doesn't give a hoot about). However, as living organisms ourselves, we tend to think that life IS important. And without replication there wouldn't be any.
 
true true...thanks jdavel...i thought there was something scientific behind its importance...is there?
 
joejo said:
my next ? is why is duplication important? is there any reason behind the importance of duplication/replication
Without the ability to duplicate, a successful molecule (ie. successful in surviving in its environment) would not proliferate. Successful molecules that duplicate themselves would proliferate. It is as simple as that.

AM
 
thanks guys! now i completely understand the importance of DNA
 

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