Which of the following is a complementary base pair for DNA adenine and cytosine guanine and cytosine adenine and guanine cytosine and thymine?

Explanation: The four nitrogenous bases of DNA are thymine, adenine, guanine, and cytosine. Guanine and cytosine are bound together by three hydrogen bonds; whereas, adenine and thymine are bound together by two hydrogen bonds. This is known as complementary base pairing.

Why adenine does not pair with guanine?

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 kind of bonds are responsible for holding together the complementary base pairs in DNA?

The hydrogen bonding between complementary bases holds the two strands of DNA together. Hydrogen bonds are not chemical bonds. They can be easily disrupted.

What is the importance of complementary base pairing?

Function. Complementary base pairing is important in DNA as it allows the base pairs to be arranged in the most energetically favourable way; it is essential in forming the helical structure of DNA. It is also important in replication as it allows semiconservative replication.

Can thymine pair with guanine?

Adenine (A) is always supposed to pair with thymine (T), and cytosine (C) is always supposed to pair with guanine (G).

Why does adenine only bond with thymine in DNA )?

Base pairing. Base pairing between adenine and thymine can be found in DNA only. There are two hydrogen bonds holding the two nitrogenous bases together. One of the hydrogen bonds is formed between one of the Hydrogen atoms of the amino group at C-6 of adenine and the Oxygen atom of the keto group at C-4 of thymine.

Why does cytosine not pair with thymine?

In order to make H bond with the both we require a hydrogen attached to an electronegative atom as well as an electronegative atom both in a particular configuration. These conditions are met by thymine and not cytosine.

Why does adenine pair with thymine and cytosine with guanine?

Well I was wondering why adenine pairs with thymine and cytosine pairs with guanine. Thymine has the lowest acidity and adenine has the biggest acidity. So it is logical that the intermolecular bond will be strong.

Why can’t adadenine pair with guanine?

Adenine can’t pair with Guanine because: Both are too large and would cause the double helix to bend out of shape. Even if they tried to pair, the hydrogen bonds wouldn’t be strong enough to resist the mechanical stress caused by their size.

How many hydrogen bonds can adenine and cytosine form?

You see, cytosine can form three hydrogen bonds with guanine, and adenine can form two hydrogen bonds with thymine. Or, more simply, C bonds with G and A bonds with T. It’s called complementary base pairing because each base can only bond with a specific base partner.

Why do nucleotides pair with DNA?

They pair because they make strong hydrogen bonds with a geometry of the base pairs that allows base stacking and is compatible with base pairing of the other nucleotides in a DNA strand. As the discussion above shows, many other base pairs are theoretically possible, and some of them are actually observed in nature.