Name: how dna stores genetic information
Uploaded: 2026-08-26T08:20:41.267Z
Duration: 1 min 27 s
Channel: JoVE

K12 Standards

Pennsylvania State Academic Standards

9-12

Life Science

Structure and Function

3.1.9-12.A

The DNA Helix

Deoxyribonucleic acid, or DNA, is made up of two polynucleotide chains.Each chain has repeating units called nucleotides, and there are four types of nucleotides.Each nucleotide has three parts: a phosphate group, a sugar called deoxyribose, and one of four bases&#x2014;adenine or A, cytosine or C, guanine or G, or thymine or T.The sugar and phosphate groups form the sugar-phosphate backbone, while the bases extend from this backbone.Along the backbone of each strand, phosphodiester bonds link the 3&#x2032; carbon of one sugar to the phosphate group attached to the 5&#x2032; carbon of the next sugar in the chain.The two strands run in opposite directions, forming an antiparallel arrangement and the bases pair in a specific way: adenine pairs with thymine and cytosine pairs with guanine. These pairs are held together by hydrogen bonds.The arrangement of base pairs and the sugar-phosphate backbone causes the DNA strands to twist around each other and form a three-dimensional double helix with about ten base pairs per turn.

the dna helix

Deoxyribonucleic acid, or DNA, is the genetic material responsible for passing traits from generation to generation in all organisms and most viruses. DNA is composed of two strands of nucleotides that wind around each other to form a double helix. The discovery of the structure of DNA occurred incrementally over nearly a century, representing one of the most famous and captivating stories in the history of science.<h4>DNA Structure in Detail</h4>Each strand of DNA consists of subunits called nucleotides that contain the sugar deoxyribose, a phosphate group, and one of four nitrogen-containing bases: adenine (A), guanine (G), cytosine (C), and thymine (T). Adenine and guanine are members of a larger class of chemicals called purines that all contain two-ringed structures. Cytosine and thymine belong to a group of single-ringed structures called pyrimidines.Adjacent nucleotides in the same strand are covalently linked by phosphodiester bonds. The two strands of nucleotides are held together by hydrogen bonds, in which the adenines in one strand pair with thymines at the same position in the other strand, and the cytosines in one strand pair with guanines in the same position in the other strand. This hydrogen bonding is made possible by the antiparallel arrangement of the two DNA strands, in which the 5&#x2019; and 3&#x2019; ends of the strands are oriented in opposite directions. Without this arrangement, the nucleotides would be in the wrong position to form hydrogen bonds between strands.The two strands of the DNA molecule are tightly wound into a spring-like structure called a double helix. However, the double helix is not perfectly symmetrical. Instead, there are regularly occurring grooves in the structure. The major groove occurs where the sugar-phosphate backbones are relatively far apart. This space grants access to DNA-binding proteins, such as transcription factors. The minor groove, by contrast, occurs where the sugar-phosphate backbones are close together. Relatively few proteins bind to DNA via the minor groove.<h4>The Discovery of DNA Structure: A Brief History</h4>The story of the discovery of DNA structure begins in 1869 when Swiss scientist Friedrich Miescher discovered a substance he called &#x201C;nuclein&#x201D;. In the process of extracting protein from white blood cells, Miescher found an unexpected substance that had relatively high phosphorus content. He did not know what it was, but he suspected that it could be biologically important. Miescher was right, but it took decades for the scientific community to fully appreciate his insights.The next critical discovery was made by Russian biochemist Phoebus Levene. In 1919, Levene proposed that nuclein, by then known as a nucleic acid, was composed of chains of molecules that he called polynucleotides. Levene&#x2019;s proposal stemmed from his research on yeast, in which he found that individual nucleotides were composed of a phosphate group, a sugar, and a nitrogen-containing base. Although Levene&#x2019;s polynucleotide model was correct in many respects, it was still unclear how the bases were arranged in the DNA molecule.The Austrian biochemist Erwin Chargaff expanded on the work of Levene. Working in the late 1940s, Chargaff made a key finding: the amount of adenine in DNA is always roughly equal to the amount of thymine, and the amount of guanine is always roughly equal to the amount of cytosine. This pattern became known as Chargaff&#x2019;s Rule and was a key piece of evidence that enabled the final elucidation of DNA structure.In the early 1950s, American biologist James Watson and English physicist Francis Crick were racing their chief rival, American Linus Pauling, to discover the three-dimensional structure of DNA. Building on the work of Chargaff, they used knowledge of physics, mathematics, and chemistry to construct physical models of DNA. But they were unsuccessful until they received a critical piece of data: an X-ray &#x2018;photograph&#x2019; of DNA that indicated in precise detail its double-helical structure. This photograph was the unpublished data of physicist Rosalind Franklin and was given to Watson and Crick without Franklin&#x2019;s knowledge. Watson and Crick published their description of DNA structure in 1953, and together with Maurice Wilkins (a co-worker of Franklin&#x2019;s), they won the 1962 Nobel Prize in Physiology or Medicine for this discovery. Sadly, Franklin died in 1958 and was therefore ineligible for a Nobel Prize.

Overview

Deoxyribonucleic acid, or DNA, is the genetic material responsible for passing traits from generation to generation in all organisms and most ...

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Education

JoVE Core

Biology

Genetics

DNA Structure and Function

KEY TERMS AND CONCEPTS

how dna stores genetic information

DNA stores genetic information that is passed from one generation to the next in organisms and most viruses. It is built from two strands of nucleotides that twist together into a double helix. The story of how scientists uncovered this structure developed step by step over nearly a century.

Each DNA strand is made of nucleotides. A nucleotide contains the sugar deoxyribose, a phosphate group, and one of four nitrogen bases: adenine (A), guanine (G), cytosine (C), or thymine (T). Adenine and guanine are purines, which have two-ring structures, while cytosine and thymine are pyrimidines, which have one ring.

Nucleotides within a strand are linked by phosphodiester bonds. The two strands are held together by hydrogen bonds between matching bases. Adenine pairs with thymine, and cytosine pairs with guanine. This pairing works because the two strands run in opposite directions, or antiparallel, with 5' and 3' ends oriented oppositely.

The twisted DNA molecule forms a spring-like double helix. It is not perfectly even, because it has repeating grooves. The major groove is where the sugar-phosphate backbones are farther apart, and it gives DNA-binding proteins such as transcription factors better access. The minor groove is narrower, and relatively few proteins bind there.

The history of DNA research began in 1869, when Swiss scientist Friedrich Miescher found a phosphorus-rich substance he called nuclein while extracting protein from white blood cells. He did not know what it was, but he suspected it mattered biologically. His insight turned out to be important, although it took many years for scientists to understand why.

In 1919, Russian biochemist Phoebus Levene proposed that nuclein, then called a nucleic acid, was made of chains he named polynucleotides. His work on yeast showed that each nucleotide includes a phosphate group, a sugar, and a nitrogen-containing base. Even so, the exact arrangement of the bases in DNA was still unknown.

That question was helped by Erwin Chargaff in the late 1940s. He found that the amount of adenine is usually about equal to thymine, and the amount of guanine is usually about equal to cytosine. This became known as Chargaff's Rule and became a key clue for the final DNA model.

In the early 1950s, James Watson and Francis Crick competed with Linus Pauling to solve DNA's three-dimensional structure. They used ideas from physics, mathematics, and chemistry to build models, but they needed one more key clue. That clue came from an X-ray photograph of DNA that showed its double-helix shape in detail. The image was unpublished data from Rosalind Franklin and was shared with Watson and Crick without her knowledge.

Watson and Crick published their description of DNA structure in 1953. Together with Maurice Wilkins, they later received the 1962 Nobel Prize in Physiology or Medicine for the discovery. Franklin had died in 1958, so she was not eligible for the prize.

How DNA Stores Genetic Information

DNA stores genetic information that is passed from one generation to the next in organisms and most viruses. It is built from two strands of nucleotides that twist together into a double helix. The story of how scientists uncovered this structure developed step by step over nearly a century. Each DNA strand is made of nucleotides. A nucleotide contains the sugar deoxyribose, a phosphate group, and one of four nitrogen bases: adenine (A), guanine (G), cytosine (C), or thymine (T). Adenine and...

dna packaging

Chromatin and Histones in DNA Packing

Eukaryotic cells must pack long DNA molecules into the nucleus, and chromatin makes that possible. DNA wraps around proteins called histones to form nucleosomes, which are the main unit of DNA packaging. Nucleosomes then coil into compact chromatin fibers. The amount of DNA in a cell is much larger than it first seems. A single human skin cell has about 3 billion base pairs of DNA, and if that DNA were stretched out in a line, it would be about 2 meters long. With about 50 trillion cells in...

organization of genes

Genes, Introns, and Regulatory DNA

Eukaryotic genes are arranged within DNA along with non-coding regions that help control gene activity. A DNA strand includes genes and intergenic regions, which are the stretches between genes. These regions do not code for proteins, but they can contain important regulatory elements such as promoters, enhancers, and silencers. A gene itself is not a single continuous coding block. It usually contains protein-coding exons and non-coding introns. After DNA is transcribed into pre-mRNA in the...

karyotyping

Chromosome Stains for Detecting Disorders

Chromosome staining helps scientists find genetic disorders by showing the number and physical features of chromosomes. These features appear after DNA condenses into chromosomes during mitosis. Cytogeneticists then stop mitosis and stain the chromosomes to study their banding pattern. The pattern reveals details such as chromosome number, shape, and type. A chromosome description like this is called a karyotype. To create one, scientists take an image of the stained chromosomes and identify...

replication in prokaryotes

How Prokaryotic DNA Is Copied

Prokaryotic DNA is copied through a coordinated process with three main stages: initiation, elongation, and termination. It begins when initiator proteins bind to the single origin of replication, or ori, on the cell’s circular chromosome. The DNA then copies around the circle in both directions, starting from two replication forks, and this produces two DNA molecules. Several proteins work together to open and protect the DNA during replication. Topoisomerase cuts one side of the...

replication in eukaryotes

Eukaryotic DNA Copying and Telomeres

Eukaryotic DNA copying is tightly regulated and must duplicate many linear chromosomes before cell division. The process is highly conserved and uses many proteins with specialized roles. It moves through initiation, elongation, and termination, and it ends with two complete sets of chromosomes in the nucleus. Eukaryotic replication shares basic steps with prokaryotic DNA replication, but the larger genome and linear chromosomes require more proteins. Replication begins at multiple origins of...

proofreading

DNA Polymerase Fixes Replication Errors

DNA polymerase helps copy DNA and fix mistakes during replication. It adds nucleotides in a sequence that matches the template DNA strand. The enzyme also has a higher affinity for the correct base, which helps keep DNA replication accurate. As new genomic DNA is made, it is synthesized in the 5’ to 3’ direction. In many cells, DNA polymerases have different jobs in this process. DNA polymerase delta and DNA polymerase epsilon can proofread when nuclear DNA is being copied. These polymerases...

mismatch repair

DNA Mismatch Repair in Replication

DNA mismatch repair fixes copying errors that happen during DNA replication. When DNA polymerase makes a mistake, the cell can detect a wrong base pair, such as A with G or T with C, and replace it with the correct nucleotide. This repair system works in both prokaryotes and eukaryotes and depends on several proteins. The Mutator protein family plays a central role in this process. In bacteria such as Escherichia coli, MutS first binds the mismatch. MutL then helps identify which strand is the...

nucleotide excision repair

DNA Damage Repair by Excision

DNA damage repair by excision protects cells from mutagens that can change DNA. Exposure to environmental mutagens can create bulky lesions that bend the double helix or block transcription. If these changes are not repaired, they can lead to mutations and may contribute to cancer or disease, depending on which DNA sequences are affected. Nucleotide excision repair, or NER, is the process that detects and removes this kind of damage. Specialized proteins scan the DNA for a damaged region, then...

mutations

DNA Changes From Point Mutations to UV Damage

Mutations are changes in the DNA sequence. They can happen by chance during DNA copying, or they can be caused by environmental factors such as radiation and chemicals. Scientists also describe mutations by how much DNA they affect, how they change a protein, and whether they happen in body cells or germline cells. Some mutations affect only one nucleotide, which is a point mutation. When a point mutation falls inside a gene, the outcome depends on how the amino acid sequence changes. A silent...

transcription

Transcription and Gene Control

Transcription and gene control explain how cells make RNA from DNA and decide which genes are active. RNA polymerase copies a DNA sequence into RNA, and this is the first step in making a protein from a gene. Many other proteins and control sequences help make messenger RNA, or mRNA, correctly. In eukaryotes, the DNA is first copied into a primary RNA, also called pre-mRNA. This RNA can then be processed into mature mRNA, which serves as the template for protein synthesis. In prokaryotes such...

translation

Protein Synthesis and mRNA Decoding

Protein synthesis begins when ribosomes decode messenger RNA (mRNA) and build a chain of amino acids. This final step of gene expression is called translation. The finished chain is a polypeptide, which can later become a functional protein. Proteins are often called the building blocks of life because they make up much of the body, from muscle fibers to hairs and immune system parts. The instructions for each protein are encoded in genes found in the DNA of every cell. In biology, the central...

bacterial transformation

Griffith’s Mouse Experiment and DNA

Bacterial transformation explains how DNA can move into bacteria and change their traits. Frederick Griffith first noticed this in 1928 while studying pneumonia-causing Streptococcus pneumoniae in mice. He compared one pathogenic strain with one non-pathogenic strain and found that only the pathogenic strain killed the host mice. Griffith made an unexpected discovery when he killed the pathogenic bacteria and mixed their remains with live, non-pathogenic bacteria. The mixture killed the mice,...

key terms and concepts

Learn how DNA stores genetic information through base pairing, the double helix, and the key discoveries by Miescher, Chargaff, Watson, Crick, and Franklin.

How DNA Stores Genetic Information | JoVE K12

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biology

Louisiana Student Standards for Science

High School

Life Sciences

from-molecules-to-organisms-structures-and-processes

From Molecules To Organisms: Structures And Processes

HS-LS1-1

ohios-learning-standards-and-model-curriculum

Ohio’s Learning Standards and Model Curriculum

Heredity

Cellular genetics

Structure and function of DNA in cells

Modern genetics

Virginia  Standards of Learning

HIgh School

BIO.5

BIO.5.a

LS.10

LS.10.a

new-jersey-student-learning-standards-for-science

New Jersey Student Learning Standards for Science

From Molecules to Organisms: Structures and Processes

Arizona Science Standards

HS+B.L3

HS+B.L3U1.11

Alabama Course of Study Science

9-12.B.1.2.a

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3.1.9-12.C

How DNA Stores Genetic Information

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