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

- [Narratore] L&#x27;acido
deossiribonucleico, o DNA,

&#xE8; composto da due catene polinucleotidi.

Ognuna di esse &#xE8; composta di
quattro sounit&#xE0; nucleotidiche,

che sono composte da un
singolo gruppo fosfato

e una base azotata,

adenina, A, citosina, C,
guanina, G, o timina, T,

connessa a uno zucchero deossiriboso.

Questa disposizione crea lo
scheletro di zucchero fosfato

della struttura del DNA.

Su un filmamento all&#x27;estremit&#xE0; 3&#x27;,

lo zucchero &#xE8; orientato
con un gruppo ossidrilico,

esposto al terzo atomo di carbonio,

il quale &#xE8; pronto per un legame covalente

con un&#x27;altra molecola di
zucchero della catena,

al quinto atomo di carbonio
mediante legame fosfodiesterico.

Nel filamento opposto,

ogni base &#xE8; accoppiata in modo unico,

C con G e A con T,

grazie alle differenze nel
numero dei legami a idrogeno

che si formano tra loro.

Questo lato complementare termina

con un gruppo fosfato all&#x27;estremit&#xE0; 5&#x27;.

Questa polarit&#xE0; chimica assicura
un imballaggio efficiente,

mantenendo i due filamenti
vicinu&#xEC;i tra loro

e formando una doppia
elica tridimensionale

con 10 coppie base per ogni avvitamento.

Pregate, Leslie. "Scoperta della struttura e della funzione del DNA: Watson e Crick." Nature Education 1, n. 1 (2008): 100. [<a href="https://www.nature.com/scitable/topicpage/discovery-of-dna-structure-and-function-watson-397">Sorgente</a>]

l'elica del dna

<h4>Panoramica</h4>

L&#x27;acido deossiribonucleico, o DNA, &#xE8; il materiale genetico responsabile del passaggio dei tratti di generazione in generazione in tutti gli organismi e nella maggior parte dei virus. Il DNA &#xE8; composto da due filamenti di nucleotidi che si snodano l&#x27;uno intorno all&#x27;altro per formare una doppia elica. La scoperta della struttura del DNA avvenne in modo incrementale nel corso di quasi un secolo, rappresentando una delle storie pi&#xF9; famose e accattivanti della storia della scienza.

<h4>Struttura del DNA in dettaglio</h4>

Ogni filamento di DNA &#xE8; costituito da sottounit&#xE0; chiamate nucleotidi che contengono il deossiribosio di zucchero, un gruppo di fosfati, e una delle quattro basi contenenti azoto: adenina (A), guanina (G), citosina (C), e timina (T). Adenina e guanina sono membri di una classe pi&#xF9; ampia di sostanze chimiche chiamate purine che contengono tutte strutture a due anelli. La citosina e la timina appartengono a un gruppo di strutture a singolo anello chiamate pirimidine.

I nucleotidi adiacenti nello stesso filamento sono covalentmente collegati da legami di fosforo. I due fili di nucleotidi sono tenuti insieme da legami di idrogeno, in cui le molecole di adenina in una coppia di un filamento con le timine nella stessa posizione nell&#x27;altro filamento, e le citosine di filamento in coppia con le guanine nella stessa posizione nell&#x27;altro filo. Questo legame idrogeno &#xE8; reso possibile dalla disposizione antiparallela dei due filamenti di DNA, in cui le estremit&#xE0; 5&#x27; e 3 &#x27; dei fili sono orientate in direzioni opposte. Senza questa disposizione, i nucleotidi sarebbero nella posizione sbagliata per formare legami di idrogeno tra i filamenti.

I due filamenti della molecola di DNA sono strettamente avvolti in una struttura a molla chiamata doppia elica. Tuttavia, la doppia elica non &#xE8; perfettamente simmetrica. al contrario, ci sono regolarmente scanalature nella struttura. La scanalatura principale si verifica dove le colonne portanti del fosfato di zucchero risultano relativamente lontane. Questo spazio consente l&#x27;accesso alle proteine che legano il DNA, come i fattori di trascrizione. La scanalatura minore, al contrario, si verifica dove le colonne portanti del fosfato di zucchero sono vicine tra loro. Relativamente poche proteine si legano al DNA attraverso la scanalatura minore.

<h4>La scoperta della struttura del DNA: una breve storia</h4>

La storia della scoperta della struttura del DNA inizia nel 1869 quando lo scienziato svizzero Friedrich Miescher scopr&#xEC; una sostanza che chiamava &#x22;nucleina&#x22;. Nel processo di estrazione di proteine dai globuli bianchi, Miescher ha scoperto una sostanza inaspettata che aveva un contenuto di fosforo relativamente elevato. Non sapeva cosa fosse, ma sospettava che potesse essere biologicamente importante. Miescher aveva ragione, ma ci sono voluti decenni perch&#xE9; la comunit&#xE0; scientifica apprezzasse appieno le sue intuizioni.

La successiva scoperta critica &#xE8; stata fatta dal biochimico russo Phoebus Levene. Nel 1919, Levene propose che i nucleini, ormai noti come acido nucleico, fosse composto da catene di molecole che chiam&#xF2; polinucleotidi. La proposta di Levene derivava dalla sua ricerca sul lievito, in cui scopr&#xEC; che i singoli nucleotidi erano composti da un gruppo di fosfati, uno zucchero e una base contenente azoto. Anche se il modello polinucleotide di Levene era corretto sotto molti aspetti, non era ancora chiaro come le basi fossero disposte nella molecola di DNA.

Il biochimico austriaco Erwin Chargaff ha ampliato il lavoro di Levene. Lavorando alla fine degli anni &#x27;40, Chargaff ha fatto una scoperta chiave: la quantit&#xE0; di adenina nel DNA &#xE8; sempre all&#x27;incirca uguale alla quantit&#xE0; di timina, e la quantit&#xE0; di guanina &#xE8; sempre all&#x27;incirca uguale alla quantit&#xE0; di citosina. Questo modello divenne noto come la regola di Chargaff ed era un elemento chiave di prova che ha permesso la chiarificazione finale della struttura del DNA.

Nei primi anni cinquanta, il biologo americano James Watson e il fisico inglese Francis Crick stavano correndo il loro principale rivale, l&#x27;americano Linus Pauling, per scoprire la struttura tridimensionale del DNA. Basandosi sul lavoro di Chargaff, hanno usato la conoscenza della fisica, della matematica e della chimica per costruire modelli fisici di DNA. Ma non hanno avuto successo fino a quando non hanno ricevuto un dato critico: una &#x22;fotografia&#x22; a raggi X del DNA che ha indicato in dettaglio la sua struttura a doppia elica. Questa fotografia &#xE8; stata i dati inediti del fisico Rosalind Franklin ed &#xE8; stata data a Watson e Crick all&#x27;insaputa di Franklin. Watson e Crick pubblicarono la loro descrizione della struttura del DNA nel 1953, e insieme a Maurice Wilkins (un collaboratore di Franklin), vinsero il Premio Nobel per la medicina nel 1962 per questa scoperta. Purtroppo, Franklin mor&#xEC; nel 1958 e fu quindi ineleggibile per un premio Nobel.

L'elica del DNA

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

Didattica

JoVE Core

Biology

Biologia

Genetics

Genetica

DNA Structure and Function

Struttura e funzione del DNA

KEY TERMS AND CONCEPTS

TERMINI E CONCETTI CHIAVE

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

the dna helix

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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JoVE Core Biologia illustra i concetti chiave della biologia grazie a oltre 300 video-lezioni animate, concise e di facile comprensione. Inoltre, negli oltre 150 video di "scienziati in azione", i concetti scientifici vengono applicati e dimostrati da ricercatori attraverso esperimenti in laboratorio.

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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Cells are the smallest and basic units of life, whether it is a single cell that forms the entire organism, e.g., in a bacterium or trillions of them, ...

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Eukaryotic Compartmentalization

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Prokaryotic Cells

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Cytoplasm

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The Nucleus

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Endoplasmic Reticulum

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Ribosomes

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Golgi Apparatus

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Lysosomes

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Plasmodesmata

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Cell Structure

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Visualizing Onion and Cheek Cells
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DNA as a Genetic Template

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DNA Packaging

Overview

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Organization of Genes

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Chromosome Structure

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The Central Dogma

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Mutations

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Proteins: From Genes to Degradation

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Taxonomy

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Phylogeny

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3.1.9-12.B

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Negative and Positive Feedback

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3.1.9-12.C

How DNA Stores Genetic Information

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