Name: transcription and rna synthesis
Uploaded: 2023-06-23T15:38:45.000Z
Duration: 1 min 17 s
Channel: JoVE

K12 Standards

Georgia Standards of Excellence

9-12

Biology

SB2.a

Transcription

La transcription est le processus de synthèse de l’ARN à partir d’une matrice d’ADN.
Sur l’ADN modèle, le complexe de pré-initiation de la transcription s’assemble autour du promoteur central d’un gène. Le promoteur comprend la boîte TATA et une séquence Initiator. Les facteurs de transcription généraux se lient au niveau de la boîte TATA, tandis que la séquence initiatrice contient le site de début de la transcription.
Une fois que les composants nécessaires sont liés, le complexe de pré-initiation déroule une courte portion de l’ADN en amont du site de début de la transcription. Après cela, les facteurs de transcription généraux se dissocient du brin et l’ARN polymérase commence à produire un nouveau brin d’ARNm.
Les nucléotides sont ajoutés un par un, et la synthèse de l’ARNm se produit dans une direction de cinq à trois premiers ordres, en lisant à partir du brin matrice, sauf que les thymidines sont remplacées par des uridines.
Ce brin d’ARNm nouvellement créé représente une copie de l’information contenue dans le brin codant. La synthèse se poursuivra jusqu’à ce qu’une séquence de terminaison soit rencontrée, qui libérera l’ARNm nouvellement fabriqué.

transcription

La transcription est la synthèse d'ARN à partir d'une séquence d'ADN par l'ARN polymérase. C'est la première étape dans la production d'une protéine à partir d'une séquence génétique. De plus, de nombreuses autres protéines et séquences régulatrices sont impliquées dans la synthèse correcte de l’ARN messager (ARNm). La régulation de la transcription est responsable de la différenciation des différents types de cellules et souvent de la réponse cellulaire appropriée aux signaux environnementaux.

La Transcription Peut Produire Différents Types de Molécules d'ARN

Chez les eucaryotes, l’ADN est d’abord transcrit en pré-ARNm, qui peut ensuite être transformé en ARNm mature pour servir de matrice pour la synthèse de protéines. Cependant, chez les procaryotes, la traduction de l’ARN en polypeptides peut commencer alors que la transcription est encore en cours. La transcription peut également produire différents types de molécules d'ARN qui ne codent pas pour les protéines, telles que les microARN (miARN), l'ARN de transfert (ARNt) et l'ARN ribosomal (ARNr), qui affectent tous la synthèse des protéines.

La Régulation de la Transcription est Centrale aux Développement

À part quelques exceptions, toutes les cellules du corps humain possèdent la même information génétique, mais différents types de cellules régulent différemment la transcription au cours du développement. Plus précisément, la régulation de la transcription joue un rôle central dans la différenciation cellulaire, le processus de production de cellules spécialisées, telles que les cellules musculaires, à partir de cellules précurseurs moins spécialisées. Certains gènes des cellules précurseurs doivent être activés et d’autres désactivés pour produire les cellules spécialisées.

Ce processus de différenciation cellulaire est orchestré par des protéines liant l'ADN, appelées facteurs de transcription, qui contrôlent le niveau de transcription des gènes. Par exemple, au début du développement des vertébrés, les cellules de la couche ectodermique de l'embryon en développement reçoivent plusieurs signaux d'induction provenant de protéines telles que BMP, WNT et SHH. Ces signaux activent des facteurs de transcription qui activent ou désactivent une multitude de gènes. De cette manière, la régulation transcriptionnelle détermine si les cellules de l’ectoderme deviennent des cellules de la peau ou des cellules du système nerveux.

La transcription est la synthèse de l’ARN à partir d’une séquence d’ADN par l’ARN polymérase. C’est la première étape de la production d’une protéine à partir d’une séquence de gène. ...

Education

Enseignement

JoVE Core

Anatomy and Physiology

Anatomie et physiologie

Unit 1

Unité 1

Essential Cellular Processes

Processus cellulaires essentiels

KEY TERMS AND CONCEPTS

TERMES ET CONCEPTS CLÉS

transcription and rna synthesis

Transcription is the process of making RNA from a DNA template. It is a key step in gene expression, because cells use the DNA sequence to build an RNA copy that can carry the message forward.

During transcription, RNA polymerase binds to DNA and reads one strand as the template. The enzyme links RNA nucleotides together in the correct order to form a growing RNA molecule. This copying step does not make DNA; it produces RNA.

The transcript focuses on the central idea of transcription as DNA to RNA transfer. Understanding this process helps students see how genetic information moves from the genome into a form the cell can use.

Transcription and RNA Synthesis

the central dogma

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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...

replication in eukaryotes

Eukaryotic DNA Copying at the Replication Fork

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types of rna

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Transcription is the process of making RNA from a DNA template. It is a key step in gene expression, because cells use the DNA sequence to build an RNA copy that can carry the message forward. During transcription, RNA polymerase binds to DNA and reads one strand as the template. The enzyme links RNA nucleotides together in the correct order to form a growing RNA molecule. This copying step does not make DNA; it produces RNA. The transcript focuses on the central idea of transcription as DNA...

translation

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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...

regulation of expression at multiple steps

regulation-of-expression-at-multiple-steps

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Cells control gene expression at several stages, from making RNA to building protein. These checkpoints include transcription, RNA processing, RNA localization, and translation. Together, they help decide when a gene is used and whether a protein is made. Transcription is controlled by regulatory proteins. Transcription factors, activators, and repressors can start or slow the transcription of genes. After transcription, the cell makes a precursor RNA, also called pre-mRNA. Pre-mRNA must be...

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Cell Cycle Stages in Cell Growth

The cell cycle is the process that controls cell growth and division. It explains how one cell makes two new cells. This process helps cells grow and reproduce.

interphase

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molecular factors affecting cell division

molecular-factors-affecting-cell-division

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what is meiosis?

Meiosis and the Formation of Gametes

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overview of cell signaling

Cell Signaling Pathways and Responses

Cell signaling pathways and responses help cells communicate and react to changes. Cells send signals to one another, and those signals can trigger a specific response in the target cell. A signal usually begins when a signaling molecule reaches a cell with the right receptor, which is a protein that receives the message. The receptor helps the cell recognize the signal and start the communication process. Inside the cell, the message can move through a signaling pathway. This pathway passes...

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g protein-coupled receptors

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cellular differentiation

From Stem Cell to Specialized Cells

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key terms and concepts

Learn how transcription uses a DNA template to build RNA, why RNA polymerase is important, and how this step fits into gene expression for high school biology.

Transcription and RNA Synthesis | 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.

The Central Dogma

Replication in Eukaryotes

Types of RNA

Translation

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What is Meiosis?

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SB2.b

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SB2.c

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

Transcription and RNA Synthesis

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