Question

The basic linkage in DNA or RNA between the sugar molecule and phosphoric acid is a phosphate __________ linkage.

Short answer

The basic linkage in DNA or RNA between the sugar molecule and phosphoric acid is a phosphate \(\textit{phosphoester}\) linkage.

Step-by-step solution

Understand the basic structure of DNA or RNA

DNA or RNA are long polymers composed of repeating units called nucleotides. Each nucleotide consists of a sugar molecule (deoxyribose in DNA, ribose in RNA), a phosphate group (phosphoric acid), and a nitrogenous base. These nucleotides are connected by covalent bonds, forming a sugar-phosphate backbone with nitrogenous bases projecting outwards.

Identify the bond between the sugar molecule and phosphoric acid

In DNA and RNA, the sugar molecule connects to the phosphoric acid through a specific covalent bond called "ester bond." The bond formed between the phosphate group's oxygen atom and the sugar's hydroxyl group is named ester bond, specifically a phosphoester bond.

Complete the sentence with the identified bond

Based on the information provided in the previous steps, we can complete the given exercise's sentence: The basic linkage in DNA or RNA between the sugar molecule and phosphoric acid is a phosphate "phosphoester" linkage.

Key concepts

DNA structure

To understand DNA structure, imagine it as a long twisted ladder. This ladder is more scientifically known as a "double helix." DNA stands for deoxyribonucleic acid, which highlights that each strand is made of repeating units called nucleotides. Each nucleotide contains three components: a sugar molecule called deoxyribose, a phosphate group, and a nitrogenous base (A, T, C, or G). The stability and structure owe to the predictable pairing of nitrogenous bases: adenine (A) pairs with thymine (T) and cytosine (C) pairs with guanine (G). These base pairs form the "rungs" of the ladder while the sugar-phosphate backbone takes the role of the "rails," providing a sturdy yet flexible structural support. This arrangement holds the key to DNA's ability to carry genetic information and ensure it’s passed down in organisms.

RNA structure

RNA, or ribonucleic acid, can be seen as the single-stranded cousin of DNA. While it, too, is composed of nucleotides, there are two key differences. First, the sugar in RNA is ribose instead of deoxyribose as in DNA. Second, the nitrogenous thymine (T) in DNA is replaced by uracil (U) in RNA. This means in RNA, adenine pairs with uracil instead of thymine, while the other base pairing, cytosine with guanine, remains the same. RNA molecules are usually single-stranded, allowing them to fold into complex three-dimensional shapes. These structures enable RNA to perform various functions like catalyzing biological reactions, delivering genetic instructions from DNA, and being a central player in protein synthesis as mRNA, tRNA, and rRNA.

sugar-phosphate backbone

The sugar-phosphate backbone is a fundamental feature of both DNA and RNA. Think of it as the structural "spine" of nucleic acids. It consists of alternating sugar and phosphate groups linked together by strong covalent bonds called phosphoester bonds - the hero of our earlier problem. In this arrangement, the sugar component provides the attachment point for the phosphate group of the next nucleotide, creating a chain-like structure. This backbone not only gives nucleic acids their basic form but also ensures stability and protection for the genetic information housed within the sequence of nitrogenous bases.

• In DNA, deoxyribose sugars and phosphate groups alternate to maintain the familiar double-stranded spiral.
• In RNA, ribose sugars form the backbone for the single-stranded structure.

The backbone plays a critical role in the replication and expression of genetic data, serving as a scaffold that enables precise gene transcription and translation.