DNA Base Pairings

  • Thread starter Spectre5
  • Start date
  • #1
182
0
In DNA, the two purines are Adenine and Guanine and the two pyrimidines are Thymine and Cytosine.

NOw...in DNA...Adenine pairs with Thymine and Guanine pairs with Cytosine. A purine pairs with a pyrimidine. That explains why Adenine cannot pair with Guanine and why Thymine cannot pair with Cytosine.

However, I do not know why Adenine cannot pair with Cytosine or Guanine with Thymine...

Does anyone know why this is? If so I would greatly appreciate some insight on this. Thanks!
 

Answers and Replies

  • #2
Moonbear
Staff Emeritus
Science Advisor
Gold Member
11,490
52
It's due to the structure of the nucleotides. Guanine and Cytosine can form three hydrogen bonds due to their conformation, and Adenine and Thymine can only form two hydrogen bonds due to their conformation.

This site shows an illustration of the locations of the hydrogen bonds that form between the two chains, which might help you understand.
http://www.morris.umn.edu/~goochv/BiolRhyt/Lectures/dna/dna.html [Broken]
Look at the illustration between points 3 and 4.
 
Last edited by a moderator:
  • #3
182
0
Thanks for explaining it and giving me the link, I get it now
 

Related Threads on DNA Base Pairings

Replies
7
Views
4K
Replies
2
Views
2K
  • Last Post
Replies
3
Views
2K
  • Last Post
Replies
15
Views
1K
Replies
2
Views
800
  • Last Post
Replies
5
Views
4K
Replies
3
Views
6K
  • Last Post
Replies
5
Views
3K
  • Last Post
Replies
10
Views
1K
  • Last Post
Replies
3
Views
2K
Top