Question

Which base will hydrogen-bond with uracil within an RNA molecule? Draw the structure of this base pair.

Short answer

In RNA, adenine (A) forms hydrogen bonds with uracil (U). The structure of the adenine-uracil base pair is as follows: \( \begin{array}{ccccccccccccc} N & {}={} & N & \leftrightarrow & O &={} & N \\ & & & & & & & & & & & &\\ & & & & & & & & & & & & \\ \downarrow \end{array} \) There are two hydrogen bonds holding the adenine and uracil bases together in this base pair.

Step-by-step solution

Identify the base that pairs with uracil in RNA

In RNA, the base-pairing rules are as follows: - Adenine (A) pairs with Uracil (U) - Cytosine (C) pairs with Guanine (G) In this case, we are looking for the base that pairs with uracil (U), which is adenine (A).

Draw the structure of the adenine-uracil base pair

To draw the structure of the adenine-uracil base pair, we will first draw the structure of each individual base and then show the hydrogen bonds that are formed between them. The structures of adenine and uracil are as follows: Adenine: \(\\ \begin{array}{ccccccccccccc} N & {}={} & \overset{\displaystyle =}{N} & & & & & & & N\ & \downarrow \end{array} \) Uracil: \(\\ \begin{array}{ccccccccccccc} O && N \\ && HN \C&\overset{\displaystyle =}{C}\\ && HC \end{array} \) Now, let's draw the adenine-uracil base pair with hydrogen bonds: \( \begin{array}{ccccccccccccc} N & {}={} & N & \leftrightarrow & O &={} & N \\ & & & & & & & & & & & &\\ & & & & & & & & & & & & \\ \downarrow \end{array} \) In the adenine-uracil base pair, there are two hydrogen bonds holding the two bases together.

Key concepts

Adenine

Adenine is one of the four nucleobases used in the formation of nucleic acids like DNA and RNA. In the language of genetics, adenine is often represented by the letter 'A'. This compound plays a crucial role in the storage and expression of genetic information.

As a fundamental component of nucleic acids, adenine pairs with thymine (T) in DNA through two hydrogen bonds. However, in RNA, which is the focus of our exercise, adenine binds with uracil (U), not thymine. This small yet significant difference is part of what distinguishes RNA from DNA. The ability for adenine to form hydrogen bonds with uracil is vital for the proper transfer of genetic information during processes like transcription and translation.

Understanding the structure of adenine, which features a combination of a fused double ring of carbon and nitrogen atoms, known as a purine, helps one to comprehend how it pairs specifically with uracil in RNA.

Uracil

Uracil is unique to RNA and is not found in DNA. Represented by the letter 'U', this nucleobase takes the place of thymine when pairing with adenine in RNA molecules. Uracil is categorized as a pyrimidine, which is a single-ringed structure consisting of carbon and nitrogen atoms.

The structure of uracil allows it to form two hydrogen bonds with adenine. This is slightly less stable than the three hydrogen bonds that form between adenine and thymine in DNA, which partially accounts for the more temporary and flexible nature of RNA. Understanding uracil's role is important, as it directly participates in the coding, decoding, regulation, and expression of genes. Its simple structure allows it to play a pivotal role in the transfer of genetic information from DNA to proteins.

Hydrogen Bonds

Hydrogen bonds are a type of weak chemical bond that is very important in the structure of nucleic acids and the pairing of nucleobases. They occur when a hydrogen atom, covalently bound to a highly electronegative atom such as nitrogen or oxygen, develops a slight positive charge and is attracted to another electronegative atom with a slight negative charge.

Within the context of RNA and our exercise, hydrogen bonds are responsible for the specific pairing of adenine with uracil, where two hydrogen bonds are formed between them. This specificity ensures accurate base pairing, which is critical for the fidelity of RNA functions like protein synthesis. Although individual hydrogen bonds are weak, the collective strength of many hydrogen bonds within a nucleic acid molecule contributes significantly to its stability and function.

Nucleic Acid Structure

The structure of nucleic acids like RNA is a key concept in biology. RNA is a single-stranded molecule that carries genetic information from DNA to the protein-making sites in the cell. The structure of RNA is determined by the sequence of its nucleobases: adenine (A), uracil (U), guanine (G), and cytosine (C).

The backbone of RNA consists of a sugar called ribose and phosphate groups, connected in a long chain from which the nucleobases protrude. RNA's structure allows it to fold into complex shapes, which is essential for its function in various biological processes, such as catalyzing chemical reactions, regulating gene expression, and acting as the genetic material for some viruses. The understanding of RNA structure, including base pairing between adenine and uracil through hydrogen bonds, is crucial for students studying genetics and molecular biology.