Name: nucleic acids and genetic information
Uploaded: 2020-11-23T11:47:33.000Z
Duration: 3 min 14 s
Channel: JoVE

Nucleic acids are polymers of nucleotides &#x2014; molecules made up of a pentose sugar, a nitrogen-containing base, and a phosphate group.There are two types of nucleic acids: Deoxyribonucleic acid, or DNA, and ribonucleic acid, or RNA. Their chemical structures differ based on the pentose sugar and nitrogenous bases they contain.The pentose sugar in RNA is ribose, which has a hydroxyl group attached to carbon-2. The sugar in DNA is deoxyribose, which has a hydrogen atom instead of a hydroxyl group at carbon-2. The nitrogenous base is bonded to carbon-1 of the sugar, while the phosphate group is attached to carbon-5.Both RNA and DNA contain the bases adenine, cytosine, and guanine. But DNA contains thymine, while RNA contains uracil.These bases are grouped into two categories: purines and pyrimidines. Adenine and guanine are purines with a double-ring structure, while the other bases are pyrimidines with a single-ring structure.In DNA and RNA, guanine and cytosine form complementary base pairs, linked by three hydrogen bonds. Adenine and thymine form base pairs in DNA, while in RNA, adenine and uracil pair together. Both pairs are linked by two hydrogen bonds.DNA and RNA polymerase enzymes catalyze the formation of nucleic acid chains by linking nucleotides together.A phosphodiester bond forms between the hydroxyl group attached to carbon-3 of one nucleotide and the phosphate group attached to carbon-5 of the next nucleotide. This reaction leaves a free phosphate group at the five-prime end and a free hydroxyl group at the three-prime end.When paired with a complementary strand, the two molecules are antiparallel, meaning one strand runs five prime to three prime, while the complementary strand runs three prime to five prime.The strands are held together by several intermolecular forces, including hydrogen bonds between bases, hydrophobic effects, and van der Waals interactions between stacked bases.DNA is a double helix made up of two polynucleotide chains wound around each other. In contrast, RNA is often found as a single-stranded molecule.However, RNA can bind to a complementary RNA or DNA strand. It can also form intra-strand complementary base pairs, resulting in different RNA secondary structures that have distinct functions within the cell.

nucleic acids

Nucleic Acids

Nucleic acids are the most important macromolecules for the continuity of life. They carry the cell&#x27;s genetic blueprint and carry instructions for its functioning.DNA and RNAThe two main types of nucleic acids are deoxyribonucleic acid (DNA) and ribonucleic acid (RNA). DNA is the genetic material in all living organisms, ranging from single-celled bacteria to multicellular mammals. It is in the nucleus of eukaryotes and in the organelles, chloroplasts, and mitochondria. In prokaryotes, the DNA is not enclosed in a membranous envelope.The cell&#x27;s entire genetic content is its genome, and the study of genomes is genomics. In eukaryotic cells but not in prokaryotes, DNA forms a complex with histone proteins to form chromatin, the substance of eukaryotic chromosomes. A chromosome can contain tens of thousands of genes. Many genes contain the information to make proteins. Other genes code for RNA products. DNA controls all of the cellular activities by turning the genes &#x22;on&#x22; or &#x22;off.&#x22;The other type of nucleic acid, RNA, is mostly involved in protein synthesis. The DNA molecules never leave the nucleus but instead use an intermediary to communicate with the rest of the cell. This intermediary is the messenger RNA (mRNA). Other types of RNA&#x2014;like rRNA, tRNA, and microRNA&#x2014;are involved in protein synthesis and its regulation.DNA and RNA consist of monomers called nucleotides. Three components comprise each nucleotide: a nitrogenous base, a pentose (five-carbon) sugar, and a phosphate group. Each nitrogenous base in a nucleotide is attached to a sugar molecule, which is attached to one or more phosphate groups. The nitrogenous bases, important components of nucleotides, are organic molecules and are so named because they contain carbon and nitrogen. They are bases because they contain an amino group that has the potential of binding an extra hydrogen, and thus decreasing the hydrogen ion concentration in its environment, making it more basic. Each nucleotide in DNA contains one of four possible nitrogenous bases: adenine (A), guanine (G), cytosine (C), and thymine (T). Adenine and guanine are classified as purines. The purine&#x27;s primary structure is two carbon-nitrogen rings. Cytosine, thymine, and uracil are classified as pyrimidines which have a single carbon-nitrogen ring as their primary structure. Each of these basic carbon-nitrogen rings has different functional groups attached to it. In molecular biology shorthand, we know the nitrogenous bases by their symbols A, T, G, C, and U. DNA contains A, T, G, and C; whereas, RNA contains A, U, G, and C.The pentose sugar in DNA is deoxyribose, and in RNA, the sugar is ribose. The difference between the sugars is the presence of the hydroxyl group on the ribose&#x27;s second carbon and hydrogen on the deoxyribose&#x27;s second carbon. The phosphate residue attaches to the hydroxyl group of the 5&#x2032; carbon of one sugar and the hydroxyl group of the 3&#x2032; carbon of the sugar of the next nucleotide, which forms a 5&#x2032;&#x2013;3&#x2032; phosphodiester linkage.DNA Double-Helix StructureDNA has a double-helix structure. The sugar and phosphate lie on the outside of the helix, forming the DNA&#x27;s backbone. The nitrogenous bases are stacked in the interior, like a pair of staircase steps. Hydrogen bonds bind the pairs to each other. Every base pair in the double helix is separated from the next base pair by 0.34 nm. The helix&#x27;s two strands run in opposite directions, meaning that the 5&#x2032; carbon end of one strand will face the 3&#x2032; carbon end of its matching strand. Only certain types of base pairing are allowed- A can pair with T, and G can pair with C. This is the complementary base rule. In other words, the DNA strands are complementary to each other.RNARibonucleic acid, or RNA, is mainly involved in the process of protein synthesis under the direction of DNA. RNA is usually single-stranded and consists of ribonucleotides that are linked by phosphodiester bonds.There are four major types of RNA: messenger RNA (mRNA), ribosomal RNA (rRNA), transfer RNA (tRNA), and microRNA (miRNA). The first, mRNA, carries the message from DNA, which controls all of the cellular activities in a cell. If a cell requires a certain protein, the gene for it turns &#x22;on&#x22; and the messenger RNA is synthesized in the nucleus. The RNA base sequence is complementary to the DNA&#x27;s coding sequence from which it has been copied. In the cytoplasm, the mRNA interacts with ribosomes and other cellular machinery.The mRNA is read in sets of three bases known as codons. Each codon codes for a single amino acid. In this way, the mRNA is read and the protein product is made. Ribosomal RNA (rRNA) is a major constituent of ribosomes on which the mRNA binds. The rRNA ensures the proper alignment of the mRNA and the ribosomes. The ribosome&#x27;s rRNA also has an enzymatic activity (peptidyl transferase) and catalyzes peptide bond formation between two aligned amino acids. Transfer RNA (tRNA) is one of the smallest of the four types of RNA, usually 70&#x2013;90 nucleotides long. It carries the correct amino acid to the protein synthesis site. It is the base pairing between the tRNA and mRNA that allows for the correct amino acid to insert itself in the polypeptide chain. MicroRNAs are the smallest RNA molecules, and their role involves regulating gene expression by interfering with the expression of certain mRNA messages.Even though the RNA is single-stranded, most RNA types show extensive intramolecular base pairing between complementary sequences, creating a predictable three-dimensional structure essential for their function.This text is adapted from <a href="https://openstax.org/books/biology-2e/pages/3-5-nucleic-acids">Openstax, Biology 2e, Chapter 3.5: Nucleic Acids</a>.

Nucleic acids are the most important macromolecules for the continuity of life. They carry the cell&#x27;s genetic blueprint and carry instructions for its ...

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nucleic acids and genetic information

Nucleic acids carry genetic information in cells. They include DNA and RNA, which are made from nucleotide building blocks. These molecules store, copy, and help use the instructions needed for life.

DNA is the main long-term storage molecule for genetic information. RNA helps carry and use that information in cells. Together, these nucleic acids connect the code in a cell to the proteins it can make.

Nucleic Acids and Genetic Information

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Nucleic acids carry genetic information in cells. They include DNA and RNA, which are made from nucleotide building blocks. These molecules store, copy, and help use the instructions needed for life. DNA is the main long-term storage molecule for genetic information. RNA helps carry and use that information in cells. Together, these nucleic acids connect the code in a cell to the proteins it can make.

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key terms and concepts

Learn how DNA and RNA store, copy, and use genetic information in cells. Explore the role of nucleic acids in high school biology.

Nucleic Acids and Genetic Information | JoVE K12

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Nucleic Acids and Genetic Information

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