Two purines and two pyrimidines together would
simply take up too much space to be able to fit in the space between the two strands
. This is why A cannot bond with G and C cannot bond with T. … The only pairs that can create hydrogen bonds in that space are adenine with thymine and cytosine with guanine.
What would happen if purines bond with purines?
If the purines in DNA strands bonded to each other instead of to the pyrimidines, they would be
so wide that the pyrimidines would not be able to reach other pyrimidines or purines on the other side
! The space between them would be so large that the DNA strand would not be able to be held together.
What would DNA look like if two purines bonded together?
Each base pair should consist of one pyrimidine and one purine, held together by hydrogen bonds. If paired correctly, each base pair will consist of three ‘rings’. If two purines paired there would be
four ‘rings
‘ and they wouldn’t fit or would distort the structure of the DNA molecule.
How are purines bonded?
Purines
always bond with pyrimidines via hydrogen bonds following the
Chargaff rule in dsDNA, more specifically each bond follows Watson-Crick base pairing rules. Therefore adenine specifically bonds to thymine forming two hydrogen bonds, whereas guanine forms three hydrogen bonds with Cytosine.
Why purines Cannot pair with each other?
Purines are large nitrogenous bases due to two nitrogen rings in their structure. Two complementary strands of the DNA can accommodate only three nitrogen rings between them. … Thus, purine-purine cannot pair with each other
due to the unavailability of the required space to bond together in the DNA double helix
.
What are 2 purines?
Nitrogenous bases present in the DNA can be grouped into two categories: purines (Adenine (A) and Guanine (G)), and pyrimidine (
Cytosine
(C) and Thymine (T)). These nitrogenous bases are attached to C1′ of deoxyribose through a glycosidic bond.
Do purines have 2 rings?
The
purines have a double ring structure
with a six-membered ring fused to a five-membered ring. Pyrimidines are smaller in size; they have a single six-membered ring structure.
How is DNA held together in the double helix?
Each molecule of DNA is a double helix formed from two complementary strands of nucleotides held together by
hydrogen bonds between G-C and A-T base pairs
.
What is responsible for holding the two strands together in the DNA double helix?
The DNA double helix is held together by
hydrogen bonds between the bases attached to the
two strands. The DNA double helix. The two sides are the sugar-phosphate backbones, composed of alternating phosphate groups and deoxyribose sugars. The nitrogenous bases face the center of the double helix.
How are two DNA strands held together?
The two strands are held together by
hydrogen bonds between the bases
, with adenine forming a base pair with thymine, and cytosine forming a base pair with guanine.
Are purines basic?
A purine is an aromatic heterocyclic nitrogen compound, composed of a pyrimidine ring system fused to an imidazole ring system, with the core molecular formula C
5
H
4
N
4
.
Purines are weakly basic compounds
.
What are the 2 pyrimidines?
Pyrimidine is one of two classes of heterocyclic nitrogenous bases found in the nucleic acids DNA and RNA: in DNA the pyrimidines are
cytosine and thymine
, in RNA uracil replaces thymine.
What DNA strands go together?
DNA base pair. Under normal circumstances, the nitrogen-containing bases
adenine (A) and thymine (T) pair together
, and cytosine (C) and guanine (G) pair together. The binding of these base pairs forms the structure of DNA .
Why does a pair with T and C with G?
The answer has to do with
hydrogen bonding that connects the bases and stabilizes the DNA molecule
. … A and T form two hydrogen bonds while C and G form three. It’s these hydrogen bonds that join the two strands and stabilize the molecule, which allows it to form the ladder-like double helix.
Can two purines be paired with one another?
The rules of base pairing (or nucleotide pairing) are: A with T:
the purine adenine (A) always pairs with the pyrimidine thymine
(T) C with G: the pyrimidine cytosine (C) always pairs with the purine guanine (G)
Why do purine and pyrimidine always pair together?
Purine always pairs with pyrimidines
due to its structural properties
. The structure of purines allows them to make hydrogen bonds with pyrimidines. Adenine bonds with thymine because both have two binding sites, so they make double hydrogen bonds.
