Quick Answer: Why Can’t Adenine Pair With Cytosine Or Guanine?

Applying similar analysis to guanine, only cytosine can make hydrogen bonds with it in the ds DNA allowing the structure of DNA as seen.

Hence adenine makes hydrogen bonds with thymine and guanine makes hydrogen bonds with cytosine.

Why does guanine pair with cytosine?

It allows something called complementary base pairing. You see, cytosine can form three hydrogen bonds with guanine, and adenine can form two hydrogen bonds with thymine. Because of complementary base pairing, the hydrogen-bonded nitrogenous bases are often referred to as base pairs.

What happens if adenine pairs with guanine?

The base pairs are adenine-thymine and guanine-cytosine in DNA, and adenine-uracil and guanine-cytosine in RNA or in hybrid DNA-RNA pairing. If adenine formed a hydrogen bond to adenine the structure would not be as stable and not form a structure suitable to build a helix.

What prevents adenine from pairing with guanine?

What prevents adenine from pairing with cytosine or guanine? Mostly the configuration of the hydrogen bonds. Cytosine and Guanine have three that match up in space while Adenine and Thymine have two that also match up. Guanine is also too long to fit as they’re both purines which are longer than pyrimidines.

What happens when adenine pairs with cytosine?

Adenine actually pairs with Thymine while Cytosine pairs with Guanine. If Adenine did pair with cytosine, then that could be the catalyst for a mutation to occur, which can cause a lot of damage in the cell.

What does cytosine always pair with?

Adenine is always paired with thymine, and guanine is always paired with cytosine. These are known as base pairs. Adenine forms two hydrogen bonds with thymine in DNA and two hydrogen bonds with uracil in RNA, while three hydrogen bonds are formed between guanine and cytosine.

What does cytosine pair with in DNA?

Each base has a specific partner: guanine with cytosine, adenine with thymine (in DNA) or adenine with uracil (in RNA). The hydrogen bonds are weak, allowing DNA to ‘unzip’.

Can adenine pair with itself?

Chargaff’s rule, also known as the complementary base pairing rule, states that DNA base pairs are always adenine with thymine (A-T) and cytosine with guanine (C-G). A purine always pairs with a pyrimidine and vice versa. However, A doesn’t pair with C, despite that being a purine and a pyrimidine.

What is the base pairing rule for RNA?

The base pairing of guanine (G) and cytosine (C) is just the same in DNA and RNA. So in RNA the important base pairs are: adenine (A) pairs with uracil (U); guanine (G) pairs with cytosine (C).

Which enzyme is responsible for proofreading replication?

Proofreading. DNA polymerases are the enzymes that build DNA in cells. During DNA replication (copying), most DNA polymerases can “check their work” with each base that they add. This process is called proofreading.