Name: how eukaryotic dna fits inside the nucleus
Uploaded: 2025-08-06T09:37:50.000Z
Duration: 58 s
Channel: JoVE

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North Carolina K-12 Science Standard Course of Study

9-12

Biology

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From Molecules to Organisms- Structures and Processes

LS.Bio.2.1

Genomic DNA in Eukaryotes

真核生物においては、二本鎖DNAは 膜結合型核の中で特別に組織化されています、細胞内の限られた領域に収納出来るように。初期段階のる圧縮において、DNAは ヒストンという特定のタンパク質の周りに固く巻き付きます。ヒストンの核およびそれに巻き付いているDNAは、併せてヌクレオソームとして知られ、DNAパッキングの基本的な単位になります。ヌクレオソームはリンカーDNAと結合し、紐上のビーズと似ています。次の段階でのパッキングでは、ヌクレオソームとリンカーDNAがコイル状に巻き付いて、クロマチン繊維を形成します。最後に、追加で他にも繊維状の蛋白質が圧縮します、クロマチンを更に圧縮し、それによって、かなりの長さの DNAが単一体の中にきつく圧縮され、これは、細胞のどの分離段階であるかによって、染色体として認識されています。

「クロマチン高次構造と遺伝子調節」 Current Opinion in Genetics & Development 21, no. 2 (April 2011): 175–86.[<a href="https://doi.org/10.1016/j.gde.2011.01.022" target="__blank">ソース</a>]

真核生物のゲノムdna

真核生物は、原核生物に比べて大きなゲノムを持ちます。大きなゲノムを細胞内に収めるため、DNAは核の中で非常にしっかりとまとめられています。そのために、DNAはヒストンと呼ばれるタンパク質にしっかりと巻き付けられることでヌクレオソームとしてまとめられ、リンカーDNAによって結合されて巻き取られることでクロマチン繊維となります。さらに繊維状のタンパク質がクロマチンを圧縮されると、細胞分裂のある段階で認識可能な染色体となります。
 
 <h4>1メートル単位で見るヒトゲノム</h4
 
 人体のほとんどの細胞には、約60億塩基対のDNAが23対の染色体にまとめられています。この数字がどれだけのDNAを表しているのかを正確に想像するのは難しく、したがって、細胞に収まるためにDNAがどれだけ密に詰まっているのかを把握するのも困難です。しかし、ゲノムを長さで表すことで、ある程度の理解を得られます。二倍体細胞1個のDNAを直線状に並べると、約2メートルの長さになります。
 
 なお、人間のゲノムが異常に大きいわけではないです。多くの魚類、両生類、顕花植物は、人間よりもはるかに大きなゲノムをもっています。例えば、日本の顕花植物であるParis japonicaの半数体ゲノムは、ヒトの半数体ゲノムの約50倍のDNAをもちます。これらの数字は、ヒストンをはじめとするクロマチン再構築タンパク質が、DNAをパッケージするために、驚くべき働きをしていることを物語っています。

真核生物のゲノムDNA

真核生物は、原核生物に比べてゲノムが大きい。彼らのゲノムを細胞に収めるために、真核生物のDNAは細胞内に非常にしっかりとパッケージ化されています...

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生物学

Cellular Processes

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Cell Cycle and Division

細胞周期と細胞分裂

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主要用語と概念

how eukaryotic dna fits inside the nucleus

Eukaryotic DNA fits inside the nucleus by packing into a highly compact form. Eukaryotes have large genomes compared with prokaryotes, so their DNA must be tightly organized to fit inside one cell.

The process starts when DNA wraps around proteins called histones. These DNA-histone units form nucleosomes, which are connected by linker DNA. The nucleosomes then coil into chromatin fibers, and additional fibrous proteins compact the chromatin even more.

This packed material is called chromatin, and it becomes recognizable as chromosomes during certain stages of cell division. In human cells, there are about 6 billion base pairs of DNA arranged into 23 pairs of chromosomes. If the DNA from one diploid cell were stretched out in a straight line, it would measure about two meters long.

Humans are not unusual in genome size. Many fish, amphibians, and flowering plants have much larger genomes than humans. The Japanese flowering plant Paris japonica has a haploid genome with about 50 times more DNA than the human haploid genome. These examples show how strongly histones and other chromatin remodeling proteins must work to package DNA.

How Eukaryotic DNA Fits Inside the Nucleus

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what is the cell cycle?

Cell Cycle Checkpoints and Cancer

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Prokaryote Chromosomes and Plasmids

Most prokaryotes store their DNA in one circular chromosome inside the nucleoid, a region of cytoplasm. This chromosome is double-stranded and tightly wound, or supercoiled, so it fits efficiently inside the cell. Prokaryotes also carry smaller circular DNA pieces called plasmids. Plasmids often carry genes that give bacteria helpful traits. One important example is antibiotic resistance. Bacteria can gain these plasmids and the traits they carry, which can help them adapt to changing...

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genomic dna in eukaryotes

Eukaryotic DNA fits inside the nucleus by packing into a highly compact form. Eukaryotes have large genomes compared with prokaryotes, so their DNA must be tightly organized to fit inside one cell. The process starts when DNA wraps around proteins called histones. These DNA-histone units form nucleosomes, which are connected by linker DNA. The nucleosomes then coil into chromatin fibers, and additional fibrous proteins compact the chromatin even more. This packed material is called chromatin,...

interphase

Interphase in the Cell Growth Cycle

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cancer

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Cancer develops when mutations affect genes that control cell division. Those changes can remove the normal brakes on growth and lead to uncontrolled cell proliferation. Modern science and medicine have improved how cancer is understood and treated, and some patients can now be cured. There is still no single cure for cancer because cancer is not one disease. It is a large group of many diseases. Even when two people have the same mutation in an oncogene or a tumor suppressor gene, their...

key terms and concepts

Learn how eukaryotic DNA is packed into nucleosomes, chromatin fibers, and chromosomes, and why histones are essential for fitting long DNA inside the nucleus.

How Eukaryotic DNA Fits Inside the Nucleus | JoVE K12

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How Eukaryotic DNA Fits Inside the Nucleus

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