Name: translation: mrna to protein
Uploaded: 2023-06-23T15:38:45.000Z
Duration: 1 min 31 s
Channel: JoVE

K12 Standards

Georgia Standards of Excellence

9-12

Biology

SB2.a

Translation

Translation ist der Prozess der Synthese eines Proteins aus einer Boten-RNA-Vorlage.
Dieser Prozess beginnt, wenn die kleine Untereinheit eines Ribosoms in einem Komplex mit einer Methionin-tRNA und Initiationsfaktoren an das fünfprimige Ende einer mRNA bindet. Der Komplex scannt die mRNA in der Richtung von fünf Primzahlen bis drei Primzahlen, bis er auf ein AUG-Codon trifft, das als Translationsinitiationsstelle dient.
Als nächstes paart sich die Methionin-tRNA mit dem AUG-Codon und rekrutiert die große Untereinheit des Ribosoms. Die Synthese des neuen Proteins beginnt, wenn eine tRNA, die ihre Aminosäure trägt, über ihr Anticodon an das nächste Codon der mRNA bindet.
Dadurch wird die neue Aminosäure in die Nähe der zuvor eingebauten Aminosäure gebracht, und zwischen den beiden Aminosäuren bildet sich eine Peptidbindung.
Die Translation wird fortgesetzt, wenn sich das Ribosom zum nächsten Codon in der Sequenz bewegt. Diese Vorwärtsbewegung wird als Translokation bezeichnet und wird so lange fortgesetzt, bis das Ribosom auf ein Stoppcodon trifft.
Stopp-Codons sind insofern einzigartig, als sie keine tRNAs enthalten. Stattdessen binden Proteine, sogenannte Freisetzungsfaktoren, an das Stoppcodon, wodurch das Ribosom das neu synthetisierte Protein freisetzt und das Ribosom dissoziiert.

Übersetzung

Unter Translation versteht man den Prozess der Synthese von Proteinen aus der genetischen Information, die in der Boten-RNA (mRNA) enthalten ist. Nach der Transkription stellt sie den letzten Schritt der Genexpression dar. Dieser Prozess wird von Ribosomen, Proteinkomplexen und spezialisierten RNA-Molekülen durchgeführt. Ribosomen, Transfer-RNA (tRNA) und andere Proteine produzieren als Endprodukt der Translation eine Kette von Aminosäuren – das Polypeptid.

Durch Übersetzung entstehen die Bausteine des Lebens

Proteine werden als Bausteine des Lebens bezeichnet, weil sie die überwiegende Mehrheit aller Organismen ausmachen – von Muskelfasern über Haare auf Ihrem Kopf bis hin zu Komponenten Ihres Immunsystems – und der Bauplan für jedes dieser Proteine durch die in ihnen vorkommenden Gene kodiert wird DNA jeder Zelle. Das zentrale Dogma der Biologie besagt, dass genetische Informationen durch die Prozesse der Transkription und Translation in funktionelle Proteine umgewandelt werden.

Die Übersetzung findet außerhalb des Kerns statt

Eukaryoten haben einen membrangebundenen Kern, in dem mRNA von DNA transkribiert wird. Nach der Transkription wird mRNA aus dem Zellkern transportiert, um in eine Kette von Aminosäuren – ein Polypeptid – und schließlich in ein funktionelles Protein übersetzt zu werden. Dies kann im Zytoplasma oder im rauen endoplasmatischen Retikulum stattfinden, wo die Polypeptide weiter modifiziert werden. Im Gegensatz dazu fehlt Prokaryoten ein Kernkompartiment, sodass die Translation bei Prokaryoten im Zytoplasma stattfindet, während die mRNA noch transkribiert wird.

Die Reihenfolge der Codons in der mRNA bestimmt die Polypeptidsequenz

Jedes Codon in der mRNA entspricht einer der 20 Aminosäuren, die eine Zelle vorrätig hat, sowie Stoppcodons, die nicht für Aminosäuren kodieren. Ein weiteres RNA-Molekül, die Transfer-RNA (tRNA), ist dafür verantwortlich, den Ribosomen während der Translation die richtige Aminosäure basierend auf der Codon-Sequenz bereitzustellen. An einem Ende des tRNA-Moleküls binden Enzyme, sogenannte Aminoacyl-tRNA-Synthetasen, die spezifische Aminosäure kovalent an die Bindungsstelle, während die Anticodon-Sequenz am anderen Ende der tRNA dafür sorgt, dass die richtige Aminosäure an das Ribosom geliefert wird. Einige tRNA-Moleküle sind in der Lage, an mehr als eine Codonsequenz zu binden, was eine Kodierungsvielfalt ermöglicht, die als Wobble-Effekt bekannt ist. Dies ist auf die Tatsache zurückzuführen, dass tRNA-Moleküle im Vergleich zu den ersten beiden Nukleotiden eine geringere Bindungsspezifität für das dritte Nukleotid in der mRNA-Codonsequenz aufweisen.

Einige Erbkrankheiten sind auf Übersetzungsfehler zurückzuführen

Die Übersetzung ist ein komplexer Prozess, der von einer Vielzahl zellulärer Komponenten abhängt. Mutationen, die einen Teil dieses vielfältigen Werkzeugkastens betreffen, können Krankheiten verursachen. Beispielsweise entsteht die Eisenspeicherkrankheit Hyperferritinämie, auch bekannt als Kataraktsyndrom, durch Mutationen in der 5'-untranslatierten Region der mRNA, einer Region, die für die Rekrutierung von Translationsinitiationsproteinen wichtig ist. Diese Mutationen führen zu ungewöhnlich hohen Translationsraten des Eisenproteins Ferritin, was dazu führt, dass es sich im Blut und Gewebe der betroffenen Patienten ansammelt. Die Folge ist eine Trübung der Augenlinsen. Andere Krankheiten stehen im Zusammenhang mit Mutationen in den Genen, die für tRNAs und ribosomale Untereinheiten kodieren. Beispielsweise ist die Knochenmarkserkrankung Diamond-Blackfan-Anämie auf Mutationen im RPS19-Gen zurückzuführen, einem Bestandteil der kleinen ribosomalen Untereinheit.

Translation ist der Prozess der Synthese von Proteinen aus der genetischen Information, die von der Boten-RNA (mRNA) getragen wird. Nach der Transkription stellt es ...

Education

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JoVE Core

Anatomy and Physiology

Anatomie und Physiologie

Unit 1

Einheit 1

Essential Cellular Processes

Essentielle Zellprozesse

KEY TERMS AND CONCEPTS

KERNBEGRIFFE UND KONZEPTE

translation: mrna to protein

Translation is the step in gene expression where ribosomes use messenger RNA, or mRNA, to build a protein. The mRNA sequence carries the instructions copied from DNA. During translation, those instructions are read in order so the cell can make a specific chain of amino acids.

This process depends on the ribosome and transfer RNA, or tRNA. The ribosome reads the mRNA, and tRNA brings the matching amino acids. As the chain grows, the amino acids are linked together to form a polypeptide, which is the start of a protein.

Translation is a key part of how cells use genetic information. It connects the message in mRNA to the final protein product. Understanding translation helps explain how genes lead to the molecules that cells need to function.

Translation: mRNA to Protein

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key terms and concepts

Learn how translation uses mRNA, ribosomes, and tRNA to build a polypeptide chain from amino acids and turn genetic information into protein.

Translation: mRNA to Protein | JoVE K12

anatomy and physiology

JoVE Core Anatomy and Physiology showcases the anatomical and physiological details of the human body in comprehensive, clear, and engaging video animations. This collection of lessons focuses on the structures, components, functions, and requirements of the human body. It is complemented by scientist-in-action videos that demonstrate the application of this knowledge in real-world medical and research settings.

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SB2.c

Obtain, evaluate, and communicate information to analyze how genetic information is expressed in cells

Translation: mRNA to Protein

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