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

Deoksiribonükleik asit veya DNA, iki polinükleotid zincirinden oluşur.
Bu zincirlerin her biri dört tip nükleotid alt biriminden oluşur.
Her nükleotid, tek bir fosfat grubundan ve bir şeker deoksiribozuna bağlı adenin, A, sitozin, C, guanin, G veya timin, T olan azot içeren bir bazdan oluşur.
Bu düzenleme, DNA yapısının şeker-fosfat omurgasını oluşturur.
Her bir ipliğin omurgası boyunca, fosfodiester bağları, bir şekerin üçüncü karbon atomunu zincirdeki bir sonraki şeker molekülünün beşinci karbon atomuna kovalent olarak bağlar.
Karşıt antiparalel ipliklerde, her bir baz, aralarında oluşan hidrojen bağlarının sayısındaki farklılıklar nedeniyle, C ile G ve A ile T olmak üzere benzersiz bir şekilde eşleştirilir.
Bu tür kimyasal polarite, her tam dönüşte on baz çifti ile 3 boyutlu bir çift sarmal oluşturmak için iki ipliği birbirinin etrafına sararak verimli bir paketleme sağlar.

dna sarmalı

Deoksiribonükleik asit veya DNA, tüm organizmalarda ve çoğu virüste özelliklerin nesilden nesile aktarılmasından sorumlu olan genetik materyaldir. DNA, çift sarmal adı verilen yay benzeri bir yapı oluşturacak şekilde birbirine dolanan iki nükleotid şeridinden oluşur. Ancak çift sarmal tam olarak simetrik değildir. Bunun yerine yapıda düzenli olarak oluşan oyuklar vardır. Ana oluk, şeker-fosfat omurgalarının nispeten birbirinden uzak olduğu yerde oluşur. Bu alan, transkripsiyon faktörleri gibi DNA bağlayıcı proteinlere erişim sağlar. Küçük oluk ise şeker-fosfat omurgalarının birbirine yakın olduğu yerde oluşur. Nispeten az sayıda protein, küçük oluk yoluyla DNA'ya bağlanır. DNA Yapısının Keşfi: Kısa Bir Tarih DNA yapısının keşfi, yaklaşık bir asır boyunca aşamalı olarak gerçekleşmiş ve bilim tarihindeki en ünlü ve büyüleyici hikayelerden birini temsil etmiştir. Her şey 1869 yılında İsviçreli bilim adamı Friedrich Miescher'in "nüklein" adını verdiği bir maddeyi keşfetmesiyle başladı. Beyaz kan hücrelerinden protein çıkarma sürecinde Miescher, nispeten yüksek fosfor içeriğine sahip beklenmedik bir madde buldu. Ne olduğunu bilmiyordu ama biyolojik olarak önemli olabileceğinden şüpheleniyordu. Miescher haklıydı ama bilim camiasının onun görüşlerini tam anlamıyla takdir etmesi onlarca yıl aldı. Bir sonraki kritik keşif Rus biyokimyacı Phoebus Levene tarafından yapıldı. 1919'da Levene, o zamanlar nükleik asit olarak bilinen nükleinin, polinükleotidler adını verdiği molekül zincirlerinden oluştuğunu öne sürdü. Levene'nin önerisi, bireysel nükleotidlerin bir fosfat grubu, bir şeker ve nitrojen içeren bir bazdan oluştuğunu bulduğu maya üzerine yaptığı araştırmadan kaynaklandı. Levene'nin polinükleotid modeli birçok açıdan doğru olmasına rağmen bazların DNA molekülünde nasıl düzenlendiği hala belirsizdi. Avusturyalı biyokimyacı Erwin Chargaff, Levene'nin çalışmalarını genişletti. 1940'ların sonlarında çalışan Chargaff önemli bir bulguya ulaştı: DNA'daki adenin miktarı her zaman kabaca timin miktarına eşittir ve guanin miktarı da her zaman kabaca sitozin miktarına eşittir. Bu model Chargaff Kuralı olarak bilinmeye başlandı ve DNA yapısının nihai olarak aydınlatılmasını sağlayan önemli bir kanıttı. 1950'lerin başında Amerikalı biyolog James Watson ve İngiliz fizikçi Francis Crick, DNA'nın üç boyutlu yapısını keşfetmek için baş rakipleri Amerikalı Linus Pauling ile yarışıyordu. Chargaff'ın çalışmalarına dayanarak, DNA'nın fiziksel modellerini oluşturmak için fizik, matematik ve kimya bilgilerini kullandılar. Ancak kritik bir veri elde edene kadar başarısız oldular: DNA'nın çift sarmal yapısını kesin ayrıntılarıyla gösteren bir X-ışını 'fotoğrafı'. Bu fotoğraf fizikçi Rosalind Franklin'in yayınlanmamış verileriydi ve Franklin'in bilgisi olmadan Watson ve Crick'e verildi. Watson ve Crick, DNA yapısına ilişkin açıklamalarını 1953'te yayınladılar ve Maurice Wilkins (Franklin'in iş arkadaşı) ile birlikte bu keşif nedeniyle 1962 Nobel Fizyoloji veya Tıp Ödülü'nü kazandılar. Ne yazık ki Franklin 1958'de öldü ve bu nedenle Nobel Ödülü'ne layık görülmedi.

DNA Sarmalı

Deoksiribonükleik asit veya DNA, tüm organizmalarda ve çoğu virüste özelliklerin nesilden nesile aktarılmasından sorumlu genetik materyaldir. DNA...

Education

JoVE Core

Cell Biology

Hücre Biyolojisi

Unit 1

Ünite 1

Cells, Genomes, and Evolution

Hücreler, Genomlar ve Evrim

KEY TERMS AND CONCEPTS

TEMEL TERİMLER VE KAVRAMLAR

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

Cells are the basic building blocks of life. A bacterium can be a single cell, while a human is made of trillions of cells. Even with this range, cells share key features that support life. A living cell has a plasma membrane. This is a bilayer of lipids that separates the cytoplasm inside the cell from the outside environment. A cell also carries genetic information in the form of DNA. In prokaryotic cells, DNA is found in a region called the nucleoid. In eukaryotic cells, DNA is enclosed...

the tree of life - bacteria, archaea, and eukaryotes

the-tree-of-life-bacteria-archaea-and-eukaryotes

Three Domains on the Tree of Life

The tree of life shows how living things are grouped into three domains: Bacteria, Archaea, and Eukaryotes. This classification helps explain the major branches of life and how they are related. Bacteria and Archaea are both single-celled organisms, but they are not the same. Eukaryotes include organisms with more complex cells, such as plants, animals, and fungi. Together, these three domains give a broad picture of life on Earth. Understanding the tree of life helps students compare cell...

prokaryotic cells

How Prokaryotes Survive Without a Nucleus

Prokaryotes are small unicellular organisms that live without a nucleus. They include the domains Archaea and Bacteria. Bacteria include common microbes such as Salmonella and E. coli, while Archaea include extremophiles that live in harsh places like volcanic springs. Prokaryotic cells still share several basic features with eukaryotic cells. They have a plasma membrane, cytoplasm, ribosomes, and genetic material in the form of single, circular DNA. Their cell parts float freely in the...

eukaryotic compartmentalization

How Organelles Keep Cells Working

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eukaryotic evolution

How Eukaryotic Cells Became Complex

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animal and plant cell structure

Plant vs Animal Cell Division and Specialization

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cytoplasm

Cytoplasm and the Cell’s Internal Support

The cytoplasm is the cell’s internal space that holds organelles and the cytoskeleton. It is suspended in the cytosol, an aqueous fluid made of water, ions, salts, and many organic molecules. This fluid helps keep the cell organized and supports many cellular activities. The cytoplasm is also where protein synthesis and protein folding take place. The watery cytosol helps proteins fold correctly. In a folded protein, hydrophobic amino acid side chains tend to stay buried in the core, while...

the nucleus

Nuclear DNA, Chromatin, and Nucleoli

The nucleus is a membrane-bound organelle that stores chromosomal DNA and helps control what proteins a eukaryotic cell makes. It acts as the cell’s control center. DNA in mitochondria and chloroplasts is different because it mainly supports functions specific to those organelles. Inside the nucleus, DNA is wrapped around proteins called histones. This DNA-protein complex is called chromatin. During interphase, when the cell is not dividing, chromatin stays loosely arranged so the DNA is easy...

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

DNA to Protein: RNA’s Role

DNA to protein flow depends on RNA as the link between genetic information and the amino acids that build proteins. Early scientists knew that DNA stores the information for cell functions and that proteins carry out most of those functions. For a long time, they did not know how the code in DNA became a working protein. At first, many people thought one gene was changed directly into its protein. Two findings in eukaryotic cells challenged that idea. Protein production does not happen in the...

mutations

Mutations in DNA and Inherited Disease

Mutations are changes in the DNA sequence. They can happen on their own during DNA copying, or they can be caused by environmental factors. Scientists describe mutations in several ways, including whether they change the amino acid sequence of a protein, how much DNA they affect, and whether they occur in somatic cells or germline cells. Some mutations are point mutations. A point mutation changes a single nucleotide in DNA. Other mutations are chromosomal alterations, which change the number...

genome size and the evolution of new genes

genome-size-and-the-evolution-of-new-genes

Genome Size and Gene Evolution

Genome size and gene evolution are linked through changes in DNA sequence and genome structure. Some genes can arise from parts of the genome that were not coding before, while others come from changes to existing genes. These shifts help explain how new genetic material can appear over time. A genome is the full set of DNA in an organism. Its size can change as DNA is added, removed, or rearranged. The transcript highlights that genome size is not fixed, and that these changes can shape the...

gene families

Shared Origins of Gene Families

Gene families are groups of related genes that share a common origin. They form when genes are copied and then change over time. These related genes can be found within the same genome. The video also connects gene families to homologous genes and orthologous genes. Homologous genes are genes with a shared evolutionary origin. Orthologous genes are homologous genes found in different species. Gene families help show how these relationships are used to study evolution and related gene functions.

gene evolution - fast or slow?

Gene Evolution Rates and Selection

Gene evolution can happen at different rates, and natural selection helps shape those changes. Some genes change slowly because important DNA changes are removed over time. Other genes can change more quickly when different mutations are kept in a population. The rate of evolution depends on how a gene is used and how strongly it is affected by selection. Genes with essential jobs often stay more similar across species. Genes under weaker pressure may show more variation and may evolve faster.<br...

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 Hücre Biyolojisi, anlaşılması kolay ancak kapsamlı animasyonlu video derslerde karmaşık hücresel süreçleri gösterir. Bu koleksiyon, organeller ve zarlar, hücresel taşıma ve hücre enerjileri dahil olmak üzere hücrelerin temel bileşenlerine ve işlevlerine odaklanır. Gerçek dünya araştırma deneylerinde hücre biyolojisinin uygulanmasını gösteren bilim insanı eylem videoları ile tamamlanmaktadır.

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.1.1

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Turnover Number and Catalytic Efficiency

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introduction-to-mechanisms-of-enzyme-catalysis

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Ribozymes

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LS.Bio.1.2

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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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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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