Table of Contents
Why does adenine always pair with thymine and guanine always pair with cytosine?
The answer has to do with hydrogen bonding that connects the bases and stabilizes the DNA molecule. The only pairs that can create hydrogen bonds in that space are adenine with thymine and cytosine with guanine. A and T form two hydrogen bonds while C and G form three.
Why adenine and thymine have double bond and guanine cytosine have triple bond?
Adenine pairs with thymine with 2 hydrogen bonds. Guanine pairs with cytosine with 3 hydrogen bonds. This creates a difference in strength between the two sets of Watson and Crick bases. Guanine and cytosine bonded base pairs are stronger then thymine and adenine bonded base pairs in DNA.
Why does guanine pair with cytosine two reasons?
Guanine and cytosine make up a nitrogenous base pair because their available hydrogen bond donors and hydrogen bond acceptors pair with each other in space. Guanine and cytosine are said to be complementary to each other.
Why does cytosine make pair with guanine and not with thymine *?
Cytosine make pair with guanine and not with adenine because hydrogen bond forming functional groups are not complementary between C and A.
How does guanine bind to cytosine?
Guanine has two tautomeric forms, the major keto form (see figures) and rare enol form. It binds to cytosine through three hydrogen bonds. In cytosine, the amino group acts as the hydrogen bond donor and the C-2 carbonyl and the N-3 amine as the hydrogen-bond acceptors.
How many hydrogen bonds hold guanine and cytosine together?
3 hydrogen bonds
The Adenine – Thymine base pair is held together by 2 hydrogen bonds while the Guanine – Cytosine base pair is held together by 3 hydrogen bonds. That is also the reason why the two strands of a DNA molecule can be separated more easily at sections that are densely populated by A – T base pairs.
What are guanine and cytosine held together by?
The Adenine – Thymine base pair is held together by 2 hydrogen bonds while the Guanine – Cytosine base pair is held together by 3 hydrogen bonds.