Name: cell compartments in eukaryotes
Uploaded: 2020-11-23T11:47:33.000Z
Duration: 1 min 46 s
Channel: JoVE

真核細胞は 内部に多数の区分があります 膜で包まれた細胞小器官により 微小環境内で 非常に特異的な機能が生じ 細胞質内部と細胞外環境の 両方から保護しています 例えば核は 内部の遺伝子を正確に調節するのに 制御された条件が必要です そのため二重の膜の 核膜で囲まれています mRNA のように どの分子が出入りできるかを 制御する孔があります さらに一部のタンパク質は 酸化的環境を必要とし 還元的なサイトゾルから 単離する必要があります それでリボソームは小胞体内で これらのタンパク質を産生し 重要な変異が生じます その後の動きは その最終目的地へと向かう途中で 小胞と呼ばれる 小さな化学的マイクロコズムの 中でも生じます ペルオキシソームなどの他の細胞小器官は 毒性化合物を水などの無害な分子に 変換する酵素を隔離して 過酸化水素など 自らの有害な副生成物から保護します 同様に リソソームも酵素を分離しますが 理由は異なります 細胞質ハーバーよりも かなり低いpHが必要な 消化反応を保護するためです ミトコンドリアは 2つの膜の間の内部が 酸性になっていて エネルギーの生産に役立ちます 全体的に見て 真核生物の区分化は もし何らかの形で格納せずに 同時に行われたなら 相容れない作用をサポートしています

「真核生物における代謝細胞内区画化の起源と進化」 Biochimie 119(2015年12月):262–68。[<a href="https://doi.org/10.1016/j.biochi.2015.03.021" target="__blank">ソース</a>]

真核生物の区画化

真核細胞を見分ける特徴の1つは、核やミトコンドリアなど、膜と結合した特定の機能を担う細胞小器官が存在することです。生体膜はごく限られた物質しか透過しないため、細胞小器官の周囲にある膜は、内部状態の制御された区画を形成します。このような微小環境は、多くの場合、周囲の細胞質環境とは異なり、細胞小器官の特定の機能に合わせて作られます。
 
 例えば、動物細胞の中で分子や細胞残骸を消化する細胞小器官のリソソームは、周囲の細胞質よりも酸性の環境を維持しています。リソソームの酵素が反応を起こすのに低いpHを必要とするからです。同様に、ミトコンドリア内でもpHは調整されており、ミトコンドリアがエネルギーを生産する機能を果たすのを助けます。
 
 さらに、タンパク質の中には、適切な折り畳みや処理のために酸化環境を必要とするものがありますが、細胞質は一般的に還元性です。したがって、これらのタンパク質は小胞体のリボソームによって作られ、そこでは必要な環境が維持されます。タンパク質はしばしば、膜に結合した小胞を介して細胞内を輸送されます。
 
 真核細胞の遺伝物質は核の中に格納されており、核は核膜と呼ばれる二重膜で囲まれています。核膜にある小孔は、核を出入りできる分子やイオンを制御します。例えば、メッセンジャーRNA（mRNA）は、この孔を通り核から出て、DNAにコードされた遺伝的説明書を持ってリボソームへ運ばれ、そこでmRNAはタンパク質へと翻訳されます。
 
 細胞小器官は、危険な物質を封じ込めたり、中和したりして細胞を保護することもできます。例えば、ペルオキシソームは酸化反応を行い、細胞にとって有害な過酸化水素を生成しますが、その過酸化水素を無害な酸素と水に変換する酵素も持ちます。このように、区画化することで、真核細胞は、必要な環境や生成される副産物の点で相容れない様々な異なる機能を実行することができます。

真核細胞の際立った特徴の1つは、核やミトコンドリアなどの膜結合オルガネラが含まれていることです。

Education

JoVE Core

Molecular Biology

分子生物学

Unit 1

ユニット1

DNA, Cells, and Evolution

DNA、細胞、そして進化

KEY TERMS AND CONCEPTS

主要用語と概念

Eukaryotic Compartmentalization

cell compartments in eukaryotes

Eukaryotic cells use compartments to organize many different jobs inside one cell. These compartments help separate processes so they can happen in the right place.

The compartment called the cytosol is the fluid part of the cell. It surrounds the other internal structures and helps support many cell processes.

Inside the cell, membrane-bound organelles create distinct microenvironments. A microenvironment is a small internal space with conditions that fit a specific task. This separation lets the cell run different reactions at the same time.

The nucleus is one of the main compartments in eukaryotic cells. It keeps the cell’s genetic material in a protected space and helps separate DNA-related activities from other work in the cytosol.

Compartmentalization is a key feature of eukaryotic cells. It improves organization and helps the cell control where important processes take place.

Cell Compartments in Eukaryotes

the dna helix

DNA Structure and Base Pairing

DNA has a helical structure that helps store genetic information. The double helix is the shape formed by two strands that twist around each other. This structure is a key feature of DNA in cells. The two strands are held together by base pairing. Bases on one strand match with bases on the other strand in a regular way. This pairing helps keep the DNA molecule stable and organized. The helix shape also helps explain how DNA fits into chromosomes and carries instructions for living things. By...

the central dogma

DNA to Protein: Central Dogma Steps

The central dogma explains how genetic information moves from DNA to RNA to protein. This flow is a key idea in molecular biology. It helps show how cells use genes to make the molecules that carry out work. DNA stores the instructions for making proteins. During transcription, a gene in DNA is copied into RNA. The RNA then carries that message to the next stage. In translation, the RNA message is used to build a protein. Proteins do much of the cell’s work, so this process connects genes to...

prokaryotic cells

Inside Prokaryotic Cell Structure

Prokaryotic cells have a simple internal structure compared with many other cells. They are usually divided into two groups: bacteria and archaea. These cells have no nucleus, so their DNA is not enclosed in a membrane-bound compartment. Instead, the genetic material is found in the nucleoid, a region where the DNA is located in the cell. Some prokaryotic cells also contain plasmids, which are small extra DNA molecules. A capsule may surround the cell and provide an additional outer layer. <br...

eukaryotic compartmentalization

Eukaryotic cells use compartments to organize many different jobs inside one cell. These compartments help separate processes so they can happen in the right place. The compartment called the cytosol is the fluid part of the cell. It surrounds the other internal structures and helps support many cell processes. Inside the cell, membrane-bound organelles create distinct microenvironments. A microenvironment is a small internal space with conditions that fit a specific task. This separation...

the tree of life - bacteria, archaea, eukaryotes

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

How Life Is Classified Into Three Domains

The tree of life shows how organisms are related through evolution. Its root represents the common ancestor of all life on Earth. From that point, branches spread out like a tree. The tips of the branches represent living, or extant, species. Species that no longer exist, called extinct species, appear closer to the center of the tree. Today, these organisms are grouped into three domains: bacteria, archaea, and eukaryotes. Scientists still debate these divisions, so the tree of life keeps...

mutations

How Mutations Change DNA

Mutations are changes in DNA. They can alter the genetic code and affect how genes work. In high school biology, students often study mutations to understand how DNA changes can influence traits. The transcript focuses on two common mutation types: point mutations and frameshift mutations. A point mutation changes one nucleotide, which is one DNA building block. A frameshift mutation happens when nucleotides are added or removed and the reading frame shifts. These changes matter because they...

gene evolution - fast or slow?

Why Some Gene Regions Evolve Faster

Gene regions do not all change at the same rate. In eukaryotes, long stretches of DNA do not code for proteins or RNAs. Some of these non-coding regions include important regulatory sequences, but most have no known function. Because little or no selection pressure acts on them, they often change the fastest over evolutionary time. Protein-coding regions usually evolve more slowly. A change in a coding sequence can alter a protein and make it less effective at doing its job. That creates...

genome size and the evolution of new genes

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

How Genome Size Shapes New Genes

Genome size can vary widely, and it also helps show how new genes form. Every living organism has a genome, whether it uses RNA or DNA. Yet the size of that genome can be very different from one organism to another. One major difference is whether the organism is prokaryotic or eukaryotic. Prokaryotic genomes usually have little to no non-coding sequence, which means genes are packed closely together in operons along the chromosome. Eukaryotic genomes contain long stretches of non-coding DNA...

gene families

How Gene Families Evolve and Diversify

Gene families are groups of genes that are thought to come from a shared ancestor. They usually form when a gene is copied by mistake during cell division. The original gene stays under selection pressure to keep its job, while the extra copy can change more quickly over time. Some copied genes gain a new role in the organism. When that happens, they are called paralogs, which are two genes in the same species that evolved from one common ancestral gene. Gene families also include orthologs,...

types of genetic transfer between organisms

types-of-genetic-transfer-between-organisms

How Genes Move Within and Across Generations

Genetic transfer is the movement of genetic information from one organism to another. It happens in two main ways: vertical gene transfer and horizontal gene transfer. Vertical gene transfer moves genes from one generation to the next. It is much more common than horizontal gene transfer. Vertical gene transfer happens during both sexual reproduction and asexual reproduction. In both cases, one or more organisms pass some or all of their genome to their offspring. This kind of transfer occurs...

key terms and concepts

Learn how eukaryotic cells use the cytosol, nucleus, and membrane-bound organelles to create microenvironments and organize cell processes.

Cell Compartments in Eukaryotes | JoVE K12

molecular biology

JoVE Core 分子生物学は、明確で簡潔なアニメーション ビデオ レッスンを通じて細胞の分子プロセスを紹介します。さらに、科学者の実際のビデオでは、これらの概念の応用が現代の研究室での実際の実験を通じて実証されています。

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Cell Compartments in Eukaryotes

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