Do You Know All Of Nucleic Acids?

During this period, you will explore nucleic acids and the historical context of biopolymers. These structures consist of monomeric units, known as nucleotides, which serve two critical roles: storing genetic information and facilitating essential biological functions. Key concepts, including the definition of nucleic acids and their relationship to biopolymers, will be discussed. "Bio" refers to life, indicating that these polymers exist within biological systems rather than being artificially created. Polymers are composed of repeated units, specifically nucleotides in this context.

Examples of different types of biopolymers include proteins, which are well-known for their various functions in the body. The focus will be on the basic structure of nucleotides, which is fundamental to understanding their role. A simple diagram will illustrate the structure of a nucleotide, which consists of a nitrogenous base, a sugar component, and phosphate groups.

The discussion will also address the significance of deoxyribose, highlighting its role in making nucleotides more stable due to the absence of an oxygen atom. This stability is crucial for their function in genetic processes. The presence of nitrogen-containing molecules is essential, as they are integral to the structure and function of nucleic acids. The human body is composed of organic compounds, including carbon, hydrogen, and oxygen, which combine to form complex ring structures and molecules.

Two main types of ring structures will be identified: single-ring structures, known as pyrimidines, and double-ring structures, classified as purines. Understanding these fundamental components is vital for comprehending the larger framework of nucleic acids and their biological significance.

Today, the focus is on the two types of nucleic acids: DNA and RNA. DNA stands for deoxyribonucleic acid, while RNA stands for ribonucleic acid. Both DNA and RNA are large organic macromolecules that consist of carbon. They are made up of nucleotides, which are the monomers of nucleic acids. Each nucleotide contains three components: a phosphate group, a five-carbon sugar (known as a pentose), and a nitrogenous base. The sugar in DNA is deoxyribose, which has one less oxygen atom than the ribose found in RNA.

In DNA, each nucleotide includes one of four nitrogenous bases: adenine, guanine, thymine, or cytosine, abbreviated as A, G, T, and C. The pairing of these bases occurs through hydrogen bonds, adhering to specific pairings: adenine pairs only with thymine, and guanine pairs only with cytosine. This is referred to as the base pair rule. Nitrogenous bases have distinct molecular shapes; adenine and guanine possess a double-ring structure, classifying them as purines, while thymine and cytosine have a single-ring structure, classifying them as pyrimidines. A helpful mnemonic is that "pyrimidine" includes a "y," correlating with thymine and cytosine.

In contrast to DNA, RNA nucleotides can include adenine, guanine, or cytosine, but instead of thymine, RNA contains uracil. Therefore, any nucleic acid with thymine is DNA, whereas those with uracil are RNA. Like thymine, uracil also has a single-ring structure and is categorized as a pyrimidine.

The nitrogenous bases play a crucial role in constructing DNA. A DNA strand forms when the phosphate group of one nucleotide bonds with the five-carbon sugar of another. The two strands of DNA are linked through hydrogen bonds between their nitrogenous bases. When DNA unwinds, these base pairs resemble the rungs of a ladder. The shape of the DNA molecule is described as a double helix, a structure first detailed by James Watson and Francis Crick in 1953, based on x-ray images taken by Rosalind Franklin.

Examining RNA, it is always single-stranded, unlike the double-stranded DNA. In eukaryotic cells, DNA is confined to the nucleus, whereas RNA can be located in both the cytoplasm and the nucleus. DNA governs heredity by holding the instructions for synthesizing proteins that compose the body, while RNA utilizes these instructions to produce all necessary proteins in a living organism. There are three types of RNA: messenger RNA (mRNA), ribosomal RNA (rRNA), and transfer RNA (tRNA).

mRNA originates in the nucleus, where it transcribes the instructions for protein assembly from the DNA. After transcription, mRNA transports these instructions to a ribosome in the cytoplasm, which consists of rRNA and proteins and acts as the site for translating the protein recipe. Finally, tRNA in the cytoplasm delivers specific amino acids to the ribosome, enabling the formation of the protein specified by the mRNA instructions.

The last type of organic macromolecule to discuss is nucleic acids. A nucleic acid is a large organic molecule composed of many smaller units. There are two primary types of nucleic acids: deoxyribonucleic acid (DNA) and ribonucleic acid (RNA). Both names include the term "nucleic acid." In living organisms, DNA serves as the main component of chromatin, which condenses to form chromosomes before cell division. The DNA within chromosomes is arranged in a specific sequence, which constitutes an organism's genes. Genes provide instructions for every function, characteristic, and activity within a living organism, including growth, reproduction, and heredity, the transmission of genes to offspring. RNA plays a crucial role in synthesizing specific proteins by correctly assembling amino acids. Proteins are essential for all cellular processes in living beings.

Nucleic acids, as organic macromolecules, contain carbon, and like proteins, they also include hydrogen, oxygen, and nitrogen. Additionally, nucleic acids contain phosphorus. The structure of nucleic acids consists of monomers called nucleotides. Each nucleotide is comprised of three components: a phosphate group containing phosphorus, a five-carbon sugar known as a pentose, and a nitrogenous base that includes nitrogen. The pentose sugar in RNA is ribose, while the sugar in DNA, known as deoxyribose, has one less oxygen atom than ribose. The nitrogenous bases found in DNA are adenine, thymine, cytosine, and guanine, commonly abbreviated as A, T, C, and G. In RNA, the bases are adenine, uracil, cytosine, and guanine, abbreviated as A, U, C, and G. DNA includes thymine, while RNA has uracil.

Nucleotide monomers link to form nucleic acids through the bonding of the phosphate group from one nucleotide to the sugar of another. This process creates a nucleic acid polymer. Although RNA and DNA both feature alternating sugar and phosphate groups, they differ in structure; RNA is single-stranded, while DNA is double-stranded. The two strands in DNA are connected by hydrogen bonds between their nitrogenous bases.

In summary, nucleic acids are organic macromolecules that include DNA and RNA, responsible for transmitting hereditary information and guiding protein synthesis in cells. They contain carbon, hydrogen, oxygen, nitrogen, and phosphorus. Nucleotides are the basic building blocks of DNA and RNA, consisting of a phosphate group, a five-carbon sugar (pentose), and a nitrogenous base. The nitrogenous bases in DNA are adenine, thymine, cytosine, and guanine, while those in RNA are adenine, uracil, cytosine, and guanine. Deoxyribose is the sugar in DNA, and ribose is the sugar in RNA.