Name: central dogma: dna to protein
Uploaded: 2025-05-22T09:05:54.000Z
Duration: 1 min 20 s
Channel: JoVE

K12 Standards

Georgia Standards of Excellence

9-12

Biology

SB2.a

The Central Dogma

Das zentrale Dogma der Molekularbiologie besagt, dass die in der DNA kodierte Information an die RNA übertragen wird, die dann auf der Grundlage dieser Anweisungen die Synthese von Proteinen steuert.
Zunächst wird bei der Transkription die DNA als Vorlage für die Synthese von Boten-RNA oder mRNA verwendet.
Die mRNA stellt eine Kopie des kodierenden DNA-Strangs dar, mit dem Unterschied, dass die Thymine durch Uracile ersetzt werden.
Als nächstes wird die mRNA durch ein Ribosom in eine Kette von Aminosäuren übersetzt.
Dabei binden Gruppen von drei Nukleotiden auf mRNA, auch Codons genannt, an komplementäre Sequenzen oder Anticodons auf den Transfer-RNA- oder tRNA-Molekülen.
Jede tRNA ist an eine bestimmte Aminosäure gebunden, abhängig vom jeweiligen Codon.
Zum Beispiel bindet das Codon CCA an eine tRNA, die an Prolin gebunden ist, während AGC an eine an Serin gebundene tRNA bindet.
Auf diese Weise gibt der genetische Code die Reihenfolge der Aminosäuren im resultierenden Polypeptid an, das zu einem funktionsfähigen Protein weiterverarbeitet wird.

das zentrale dogma

Das zentrale Dogma erklärt den Fluss der genetischen Information von DNA-Nukleotiden bis zur Aminosäuresequenz von Proteinen.

RNA ist das fehlende Bindeglied zwischen DNA und Proteinen

Im frühen 20. Jahrhundert entdeckten Wissenschaftler, dass die DNA alle für Zellfunktionen erforderlichen Informationen speichert und dass Proteine die meisten dieser Funktionen erfüllen. Allerdings blieben die Mechanismen der Umwandlung genetischer Informationen in funktionelle Proteine viele Jahre lang unbekannt. Ursprünglich glaubte man, dass ein einzelnes Gen direkt in sein kodiertes Protein umgewandelt wird. Zwei entscheidende Entdeckungen in eukaryotischen Zellen stellten diese Theorie in Frage. Erstens findet die Proteinproduktion nicht im Zellkern statt. Zweitens ist DNA außerhalb des Zellkerns nicht vorhanden. Diese Erkenntnisse lösten die Suche nach einem Zwischenmolekül aus, das die DNA mit der Proteinproduktion verbindet. Es wurde festgestellt, dass es sich bei diesem Zwischenmolekül um RNA handelt.

RNA wird im Zellkern unter Verwendung von DNA als Matrize synthetisiert. Die neu synthetisierte RNA ähnelt in ihrer Sequenz dem DNA-Strang, außer dass Thymin durch Uracil ersetzt wird. In Eukaryoten wird dieses Primärtranskript weiterverarbeitet, wobei die nicht-kodierenden Regionen des Proteins entfernt, das 5'-Ende abgedeckt und ein 3'-Poly-A-Schwanz hinzugefügt wird, um reife mRNA zu erzeugen, die dann in das Zytoplasma exportiert wird.

Der genetische Code ist redundant

Proteine werden in Eukaryoten aus 20 Aminosäuren gebildet. Die Kombination von vier Nukleotiden in Dreiergruppen ergibt 64 (43) mögliche Codons. Das bedeutet, dass mehr als ein Codon eine einzelne Aminosäure kodieren kann. Daher wird der genetische Code als redundant oder degeneriert bezeichnet. Oft, aber nicht immer, unterscheiden sich Codons, die dieselben Aminosäuren spezifizieren, nur im dritten Nukleotid des Tripletts. Beispielsweise repräsentieren die Codons GUU, GUC, GUA und GUG alle die Aminosäure Valin. Allerdings ist AUG das einzige Codon, das die Aminosäure Methionin repräsentiert. Das Codon AUG ist auch das Codon, an dem die Proteinsynthese beginnt, und wird daher als Startcodon bezeichnet. Redundanz im System minimiert die schädlichen Auswirkungen von Mutationen. Beispielsweise verändert eine Veränderung an der dritten Position des Codons möglicherweise nicht unbedingt die kodierte Aminosäure und führt somit zu keiner Änderung der Proteinfunktionalität.

Der genetische Code ist universell

Mit wenigen Ausnahmen verwenden die meisten prokaryotischen und eukaryotischen Organismen denselben genetischen Code für die Proteinsynthese. Diese Universalität des genetischen Codes hat Fortschritte in der wissenschaftlichen Forschung auf dem Gebiet der Landwirtschaft und Medizin ermöglicht. Beispielsweise kann menschliches Insulin heute mithilfe rekombinanter DNA-Technologie in großem Maßstab in Bakterien hergestellt werden. Bei der rekombinanten DNA-Technologie wird genetisches Material verschiedener Arten verwendet. Gene, die für menschliches Insulin kodieren, werden mit bakterieller DNA verbunden und in eine Bakterienzelle eingefügt. Die Bakterienzelle führt dann Transkription und Translation durch, um das menschliche Insulinprotein zu produzieren, das zur Behandlung von Diabetes bei Patienten eingesetzt werden kann.

Das zentrale Dogma

Das zentrale Dogma erklärt den Fluss genetischer Information von DNA-Nukleotiden zur Aminosäuresequenz von Proteinen.
RNA ist das fehlende Bindeglied zwischen ...

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

central dogma: dna to protein

The central dogma explains how genetic information flows in cells from DNA to RNA to protein. It is a core idea in molecular biology and helps show how genes influence cell function.

DNA stores the instructions. During transcription, a cell copies a gene into RNA, which is a related nucleic acid. That RNA message can then be used in translation to build a protein.

Proteins carry out many jobs in cells and help determine traits. The central dogma links the genetic code in DNA to the molecules that do most of the work in living systems.

Central Dogma: DNA to Protein

the central dogma

The central dogma explains how genetic information flows in cells from DNA to RNA to protein. It is a core idea in molecular biology and helps show how genes influence cell function. DNA stores the instructions. During transcription, a cell copies a gene into RNA, which is a related nucleic acid. That RNA message can then be used in translation to build a protein. Proteins carry out many jobs in cells and help determine traits. The central dogma links the genetic code in DNA to the molecules...

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key terms and concepts

Explore the central dogma and how genetic information moves from DNA to RNA to protein. Learn how transcription and translation connect genes to proteins.

Central Dogma: DNA to Protein | JoVE K12

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Central Dogma: DNA to Protein

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