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

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Biology

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From Molecules to Organisms- Structures and Processes

LS.Bio.2.1

Genomic DNA in Eukaryotes

- [Инструктор] У эукариот двухцепочечная ДНКспециально организована в мембраносвязанном ядречтобы разместиться в ограниченном пространстве клетки. 
На первом уровне компактизацииДНК плотно обернута вокругопределенных белков, называемых гистонами. 
Гистоновое ядро и ДНК, обернутая вокруг него,вместе известны как нуклеосома,основная единица упаковки ДНК. 
Нуклеосомы соединяются вместе линкерной ДНК,чтобы создавать форму бус на веревочке. 
На следующем уровне упаковки нуклеосомы и линкерная ДНКобвиваются, образуя хроматиновые волокна. 
Наконец, дополнительные волокнистые белки еще большеуплотняют хроматин, позволяя таким длинным отрезкам ДНКобразовывать такие плотно конденсированные единицы,которые распознаются как хромосомы,в зависимости от фазы деления клетки.

Ли, Гохун и Дэнни Рейнберг. "Структуры хроматина высшего порядка и регуляция генов." Current Opinion in Genetics & Development 21, No2 (апрель 2011): 175–86 [<a href="https://doi.org/10.1016/j.gde.2011.01.022" target="__blank">Источник</a>]

Геномы эукариот

Эукариоты имеют большие геномы по сравнению с прокариотами. Чтобы поместить их геномы в клетку, эукариотическая ДНК упакована чрезвычайно плотно внутри ядра. Для достижения этой цели, ДНК плотно раны вокруг белков, называемых гистоны, которые упакованы в нуклеосомы, которые соединены связующим ДНК и катушки в хроматиновых волокон. Дополнительные волокнистые белки еще больше уплотняет хроматин, который узнаваем как хромосомы на определенных этапах деления клеток.

<h4>Геном человека измеряется в метрах</h4>

Большинство клеток в организме человека содержат около 6 миллиардов базовых пар ДНК, упакованных в 23 пары хромосом. Трудно представить, сколько именно ДНК представляют эти цифры, и поэтому трудно понять, насколько плотно упакованная ДНК должна быть, чтобы поместиться в клетку. Мы можем получить некоторое представление, выражая геном с точки зрения длины. Если бы мы организовали ДНК одной диплоидной клетки в прямую линию, она была бы около двух метров в длину!

Обратите внимание, что у людей не такие уж большие геномы. Многие рыбы, земноводные и цветущие растения имеют гораздо большие геномы, чем люди. Например, гаплоидный геном японского цветущего растения Paris japonica содержит примерно в 50 раз больше ДНК, чем геном гаплоиды человека. Эти цифры подчеркивают удивительную работу, которую гистоны и другие хроматин ремоделирования белков должны сделать, чтобы упаковать ДНК.

Эукариоты имеют большие геномы по сравнению с прокариотами. Чтобы уместить их геномы в клетке, эукариотическая ДНК чрезвычайно плотно упакована внутри клетки.

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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

The cell cycle is the set of steps a eukaryotic cell follows as it grows and divides. In somatic cells, it has two main stages: interphase and the mitotic phase. During interphase, the cell grows, carries out its basic metabolic functions, copies its DNA, and gets ready for mitotic cell division. After interphase, the cell enters mitosis and cytokinesis. Mitosis divides the nuclear material, and cytokinesis divides the cytoplasm. These steps produce two daughter cells that are identical to the...

genomic dna in prokaryotes

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...

binary fission

How Cells Split by Binary Fission

Binary fission is a common way that bacteria and archaea reproduce. In this process, one parent cell divides into two parts. Each new cell can then grow to the size of the original parent cell. This is an asexual form of reproduction, so the cells produced are genetically identical. Binary fission can happen very fast. In the time it takes one bacterial cell to divide, the number of cells in the culture doubles. That time is called the doubling time. Escherichia coli cells often divide every...

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

Interphase is the stage of the cell cycle when a eukaryotic cell grows and copies its DNA before mitosis. In a typical human cell, the full cell cycle takes about 24 hours, and interphase makes up about 95 percent of that time. It is followed by mitosis, also called M, when the cell divides. After mitosis and cytokinesis, cells enter the G1 phase, or gap 1. During G1, cells grow continuously and prepare for DNA replication. They are metabolically active and copy essential organelles and...

mitosis and cytokinesis

Cell Cycle Stages in Mitosis

Cell cycle stages in mitosis show how a eukaryotic cell copies its DNA and then divides into two daughter cells. The cycle is controlled by regulatory systems and by outside signals that affect cell growth and division. In typical human cells, the full cycle takes about 24 hours and includes two major phases. The first is DNA replication during the S phase of interphase. The second is the mitotic, or M, phase, which includes mitosis and cytokinesis. G1 and G2 are the gap stages between these...

positive regulator molecules

Cyclins and CDKs in the Cell Cycle

Cyclins and CDKs help control the cell cycle, the process that produces daughter cells. Cells use internal checkpoints to make sure their size, energy reserves, and DNA are ready before they move forward. At these checkpoints, positive regulators help the cell continue, while negative regulators slow or stop it. The main positive regulators are cyclins and cyclin-dependent kinases, or CDKs. These proteins are found in eukaryotes, from yeast to humans. Cyclins are grouped by the stage they help...

negative regulator molecules

Cell Cycle Stop Signals: p53, p21, and Rb

Cell cycle stop signals help control when a cell can move forward through division. Negative regulators pause or end the cell cycle until the cell meets the right conditions. Three well-studied negative regulators are p53, p21, and retinoblastoma protein, or Rb. Their roles became clear after faulty versions were found in cancer cells that kept replicating uncontrollably. These proteins act mostly at the G1 checkpoint, which comes early in the cell cycle. P53 has a strong effect on whether a...

cancer

Cancer Treatment, Personalization, and Cell Growth

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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