Name: how dna structure was discovered
Uploaded: 2023-04-30T10:29:48.000Z
Duration: 1 min 7 s
Channel: JoVE

K12 Standards

north-carolina-k-12-science-standard-course-of-study

North Carolina K-12 Science Standard Course of Study

9-12

Biology

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

From Molecules to Organisms- Structures and Processes

LS.Bio.1.5

The DNA Helix

O ácido desoxirribonucléico, ou DNA, consiste em duas cadeias de polinucleotídeos.
Cada uma dessas cadeias é composta por quatro tipos de subunidades de nucleotídeos.
Cada nucleotídeo consiste em um único grupo fosfato e uma base contendo nitrogênio - adenina, A, citosina, C, guanina, G ou timina, T, ligada a uma desoxirribose de açúcar.
Esse arranjo cria a estrutura de açúcar-fosfato da estrutura do DNA.
Ao longo da espinha dorsal de cada fita, as ligações fosfodiéster ligam covalentemente o terceiro átomo de carbono de um açúcar ao quinto átomo de carbono da próxima molécula de açúcar na cadeia.
Nas fitas antiparalelas opostas, cada base é emparelhada de forma única, C com G e A com T, devido às diferenças no número de ligações de hidrogênio que se formam entre elas.
Essa polaridade química garante um empacotamento eficiente, enrolando os dois fios um ao redor do outro para formar uma dupla hélice 3-D, com dez pares de bases a cada volta completa.

a hélice do dna

O ácido desoxirribonucléico, ou DNA, é o material genético responsável pela transmissão de características de geração em geração em todos os organismos e na maioria dos vírus. O DNA é composto de duas cadeias de nucleotídeos que se enrolam para formar uma estrutura semelhante a uma mola chamada dupla hélice. No entanto, a dupla hélice não é perfeitamente simétrica. Em vez disso, existem ranhuras que ocorrem regularmente na estrutura. O sulco principal ocorre onde as estruturas açúcar-fosfato estão relativamente distantes umas das outras. Este espaço concede acesso a proteínas de ligação ao DNA, como fatores de transcrição. O sulco menor, por outro lado, ocorre onde as estruturas açúcar-fosfato estão próximas umas das outras. Relativamente poucas proteínas se ligam ao DNA através do sulco menor. A descoberta da estrutura do DNA: uma breve história A descoberta da estrutura do DNA ocorreu de forma incremental ao longo de quase um século, representando uma das histórias mais famosas e cativantes da história da ciência. Tudo começou em 1869, quando o cientista suíço Friedrich Miescher descobriu uma substância que chamou de “nucleína”. No processo de extração de proteínas dos glóbulos brancos, Miescher encontrou uma substância inesperada que tinha um teor relativamente alto de fósforo. Ele não sabia o que era, mas suspeitava que pudesse ser biologicamente importante. Miescher estava certo, mas foram necessárias décadas para que a comunidade científica apreciasse plenamente as suas ideias. A próxima descoberta crítica foi feita pelo bioquímico russo Phoebus Levene. Em 1919, Levene propôs que a nucleína, então conhecida como ácido nucleico, era composta por cadeias de moléculas que ele chamou de polinucleotídeos. A proposta de Levene resultou de sua pesquisa com leveduras, na qual descobriu que os nucleotídeos individuais eram compostos de um grupo fosfato, um açúcar e uma base contendo nitrogênio. Embora o modelo polinucleotídico de Levene estivesse correto em muitos aspectos, ainda não estava claro como as bases estavam organizadas na molécula de DNA. O bioquímico austríaco Erwin Chargaff expandiu o trabalho de Levene. Trabalhando no final da década de 1940, Chargaff fez uma descoberta importante: a quantidade de adenina no DNA é sempre aproximadamente igual à quantidade de timina, e a quantidade de guanina é sempre aproximadamente igual à quantidade de citosina. Esse padrão ficou conhecido como Regra de Chargaff e foi uma evidência chave que permitiu a elucidação final da estrutura do DNA. No início da década de 1950, o biólogo americano James Watson e o físico inglês Francis Crick competiam com seu principal rival, o americano Linus Pauling, para descobrir a estrutura tridimensional do DNA. Com base no trabalho de Chargaff, eles usaram conhecimentos de física, matemática e química para construir modelos físicos de DNA. Mas não tiveram sucesso até receberem um dado crítico: uma “fotografia” de raios X do DNA que indicava com detalhes precisos a sua estrutura em dupla hélice. Esta fotografia era um dado não publicado da física Rosalind Franklin e foi dada a Watson e Crick sem o conhecimento de Franklin. Watson e Crick publicaram a sua descrição da estrutura do DNA em 1953 e, juntamente com Maurice Wilkins (um colega de trabalho de Franklin), ganharam o Prémio Nobel de Fisiologia ou Medicina de 1962 por esta descoberta. Infelizmente, Franklin morreu em 1958 e, portanto, não era elegível para o Prêmio Nobel.

A Hélice do DNA

O ácido desoxirribonucléico, ou DNA, é o material genético responsável por passar características de geração em geração em todos os organismos e na maioria dos vírus. ADN...

Education

JoVE Core

Cell Biology

Biologia Celular

Unit 1

Unidade 1

Cells, Genomes, and Evolution

Células, Genomas e Evolução

KEY TERMS AND CONCEPTS

TERMOS-CHAVE E CONCEITOS

how dna structure was discovered

DNA is the genetic material that passes traits from one generation to the next in organisms and most viruses. It is made of two strands of nucleotides that twist into a spring-like double helix. The shape is not perfectly even. It also has repeating grooves called the major groove and the minor groove.

The major groove forms where the sugar-phosphate backbones are farther apart. This wider space gives DNA-binding proteins, including transcription factors, better access to the bases. The minor groove forms where the backbones are closer together. Relatively few proteins bind to DNA through the minor groove.

The story of DNA structure unfolded over nearly a century. It began in 1869, when Swiss scientist Friedrich Miescher found a phosphorus-rich substance in white blood cells and called it nuclein. He did not know what it was, but he suspected it had biological importance. Later work showed that his idea was right.

In 1919, Russian biochemist Phoebus Levene proposed that nucleic acid was made of chains of molecules called polynucleotides. His yeast studies showed that each nucleotide contains a phosphate group, a sugar, and a nitrogen-containing base. This model was useful, but it still did not explain how the bases were arranged in DNA. In the late 1940s, Erwin Chargaff added a key clue by showing that adenine is roughly equal to thymine and guanine is roughly equal to cytosine.

That evidence helped James Watson and Francis Crick build their DNA models in the early 1950s. They were competing with Linus Pauling and used ideas from physics, mathematics, and chemistry. They succeeded only after seeing an X-ray photograph of DNA that showed the double helix in detail. The image came from Rosalind Franklin’s unpublished data and was shared without her knowledge. Watson and Crick published their description in 1953, and with Maurice Wilkins they received the 1962 Nobel Prize in Physiology or Medicine. Franklin died in 1958, so she was not eligible for the prize.

How DNA Structure Was Discovered

what are cells?

Cells as the Building Blocks of Life

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the tree of life - bacteria, archaea, and eukaryotes

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prokaryotic cells

How Prokaryotes Survive Without a Nucleus

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eukaryotic compartmentalization

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eukaryotic evolution

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animal and plant cell structure

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cytoplasm

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the nucleus

Nuclear DNA, Chromatin, and Nucleoli

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the dna helix

DNA is the genetic material that passes traits from one generation to the next in organisms and most viruses. It is made of two strands of nucleotides that twist into a spring-like double helix. The shape is not perfectly even. It also has repeating grooves called the major groove and the minor groove. The major groove forms where the sugar-phosphate backbones are farther apart. This wider space gives DNA-binding proteins, including transcription factors, better access to the bases. The minor...

the central dogma

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mutations

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genome size and the evolution of new genes

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gene families

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gene evolution - fast or slow?

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types of genetic transfer between organisms

types-of-genetic-transfer-between-organisms

Vertical and Horizontal Gene Transfer

Genetic transfer between organisms happens in two main ways: vertical gene transfer and horizontal gene transfer. These two routes explain how hereditary material moves from one generation to the next or between organisms that are not parent and offspring. Vertical gene transfer passes genes from parent to offspring during reproduction. This is the usual way genetic information is inherited in living things. Horizontal gene transfer moves genetic material between organisms outside of...

key terms and concepts

Explore how scientists uncovered DNA’s double helix, from Miescher’s nuclein to Chargaff’s rule, Franklin’s X-ray image, and Watson and Crick.

How DNA Structure Was Discovered | JoVE K12

cell biology

JoVE Core - Biologia Celular ilustra processos celulares complexos em vídeos de animação fáceis de entender e, ao mesmo tempo, abrangentes. Esta coleção foca nos componentes e funções essenciais das células, incluindo organelas e membranas, transporte celular e energia celular. É complementado por vídeos de Cientistas em ação que demonstram a aplicação da biologia celular em experimentos de pesquisa do mundo real.

Pennsylvania State Academic Standards

Life Science

Inheritance and Variation of Traits

3.1.9-12.P

3.1.9-12.Q

Louisiana Student Standards for Science

High School

Life Sciences

From Molecules To Organisms: Structures And Processes

HS-LS1-1

heredity-inheritance-and-variation-of-traits

Heredity: Inheritance And Variation Of Traits

HS-LS3-1

Biological Evolution: Unity And Diversity

HS-LS4-1

Tennessee Academic Standards

From Molecules to Organisms: Structures and Processes

BIO1.LS1.3

Virginia  Standards of Learning

HIgh School

BIO.2

BIO.2.d

BIO.5

BIO.5.b

Minnesota Academic Standards in Science

3.1.1 9L.3.1.1.4

Florida Department of Education

SC.912.L.16

SC.912.L.16.4

SC.912.L.18

SC.912.L.18.1

Texas Essential Knowledge and Skills

BIO.7

BIO.7.A

south-carolina-college-and-career-ready-science-standards

South Carolina College and Career Ready Science Standards

B-LS1-1.

Heredity: Inheritance and Variation of Traits

B-LS3-1.

Georgia Standards of Excellence

SB6.c

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LS.Bio.1.3

Analyze how the relationship between structure and function supports life processes within organisms.

How DNA Structure Was Discovered

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