Name: genes, introns, and regulatory dna
Uploaded: 2026-08-26T08:20:12.834Z
Duration: 2 min 39 s
Channel: JoVE

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Life Science

Structure and Function

3.1.9-12.A

Organization of Genes

Neben der komplexen Anordnung des genetischen Materials im Zellkern weisen die menschlichen Gene auch eine einzigartige Anordnung auf.
 Zwischen den Chromosomen sind &#xFC;ber 20.
 000 Gene verteilt, die manchmal durch weite Strecken nicht-kodierender DNA oder der, die Proteine nicht kodiert, geteilt sind.
 Der Schl&#xFC;ssel zur Anordnung eines einzelnen Gens ist der Promotor, an den sich Maschinen, insbesondere RNA-Polymerase, anlagern k&#xF6;nnen.
 Wenn dieses Enzym eine nahe Transkriptionsinitiationsstelle erkennt, beginnt es, einen RNA-Strang unter Verwendung von DNA als Vorlage zu erzeugen.
 Die Polymerase durchl&#xE4;uft dann das genetische Material und liefert weiterhin RNA, bis sie die Transkriptionsterminationssequenz eines Gens identifiziert, wodurch der Prozess gestoppt wird.
 Wichtig ist, dass zwischen diesen Start- und Endpunkten Bereiche liegen, die als Introns und Exons bezeichnet werden und sich beide im RNA-Produkt widerspiegeln.
 Die nachfolgenden Prozesse entfernen jedoch Introns aus diesem Transkript.
 Da diese RNA zur Erzeugung von Proteinen verwendet wird, werden Exons als kodierende Regionen bezeichnet, wobei Introns ein weiteres Beispiel f&#xFC;r nicht kodierendes Material sind.
 Interessanterweise assoziieren auch andere Arten von nicht-kodierender DNA wie Silencer mit Genen.
 Als Repressoren bezeichnete Proteine binden an diese Regionen und verhindern, dass die Polymerase-Promotor Assoziation die Transkription hemmt.
 Infolgedessen helfen Silencer, die Genexpression zu regulieren.
 Ein Gen besteht also aus verschiedenen Komponenten.
 Darunter sind ein Promotor, Exons, Introns und regulatorische Elemente.
 Diese tragen zusammen dazu bei, die Proteinexpression in einer Zelle zu bestimmen.

1. William Roy, Scott und Walter Gilbert. "Die Evolution der spleißosomalen Introns: Muster, Rätsel und Fortschritt." Nature Reviews Genetics 7, Nr. 3 (März 2006): 211–21. <a href="https://doi.org/10.1038/nrg1807">https://doi.org/10.1038/nrg1807</a>.

organisation der gene

<h4>&#xDC;berblick</h4>
 
 Die Genome von Eukaryoten k&#xF6;nnen in mehrere funktionale Kategorien untergliedert werden. Ein DNA-Strang besteht aus Genen und intercistronischen Regionen. Die Gene selbst bestehen aus proteinkodierenden Exons und nicht-kodierenden Introns. Introns werden bei der Transkription der Sequenz zu mRNA ausgeschnitten, so dass nur Exons f&#xFC;r Proteine kodieren.
 
 <h4>Eukaryotische Gene sind durch intercistronische Regionen getrennt</h4>
 
 In eukaryotischen Genomen sind Gene durch gro&#xDF;e DNA-Abschnitte getrennt, die nicht proteinkodierend sind. Diese intercistronischen Regionen tragen jedoch wichtige Elemente, die die Genaktivit&#xE4;t regulieren, z.B. den Promotor, wo die Transkription beginnt, sowie Enhancer und Silencer, die die Genexpression feinjustieren. Manchmal k&#xF6;nnen diese Bindungsstellen weit vom assoziierten Gen entfernt sein.
 
 <h4>Proteinkodierende Exons sind mit Introns durchsetzt</h4>
 
 Als die Forscher den Prozess der Gentranskription in Eukaryoten untersuchten, stellten sie fest, dass die endg&#xFC;ltige mRNA, die ein Protein kodiert, k&#xFC;rzer als die DNA ist, von der sie abgeleitet ist. Dieser L&#xE4;ngenunterschied ist auf einen Prozess zur&#xFC;ckzuf&#xFC;hren, der Splei&#xDF;en genannt wird. Sobald die pr&#xE4;-mRNA von der DNA im Zellkern transkribiert wurde, werden beim Splei&#xDF;en sofort Introns entfernt und Exons miteinander verbunden. Das Ergebnis ist proteinkodierende mRNA, die ins Zytoplasma transportiert wird und in ein Protein umgeschrieben wird.
 
 <h4>Die Anzahl der Introns pro Gen kann deutlich variieren</h4>
 
 Eines der gr&#xF6;&#xDF;ten menschlichen Gene, DMD, ist &#xFC;ber zwei Millionen Basenpaare lang. Dieses Gen kodiert das Muskelprotein Dystrophin. Mutationen in DMD verursachen Muskeldystrophie, eine Krankheit, die durch fortschreitenden Muskelabbau charakterisiert ist. Dieses Gen enth&#xE4;lt 79 Exons und 103 Introns. Am anderen Ende des Spektrums liegt das Histon-H1A-Gen, welches das kleinste Gen im menschlichen Genom ist mit nur 781 Basenpaaren L&#xE4;nge und einem Exon und keinen Introns.
 
 <h4>Introns f&#xFC;hren wichtige Funktionen aus</h4>
 
 Sind Introns Abfall-DNA, die entfernt werden muss? Interessanterweise k&#xF6;nnen Introns Elemente tragen, die f&#xFC;r die Genregulation wichtig sind. Au&#xDF;erdem erlaubt das Spei&#xDF;en des anf&#xE4;nglichen Transkripts und das Zusammenf&#xFC;gen der Exons ein Mischen der DNA-Sequenzen. Dieser Prozess des Mischens und Zusammenf&#xFC;gens der Exons wird als alternatives Splei&#xDF;en bezeichnet. Er erm&#xF6;glicht es, mehrere Proteinvarianten aus einer einzigen kodierenden Sequenz herzustellen.
 
 <h4>Die &#xFC;berwiegende Mehrheit des menschlichen Genoms kodiert keine Protein &gt;/strong&gt;</h4>
 
 Wussten Sie, dass 99% Ihres Genoms keine Proteine kodieren? In den fr&#xFC;hen Tagen der Genomforschung pr&#xE4;gten Biologen den eing&#xE4;ngigen Begriff Junk-DNA (&#x201E;M&#xFC;ll-DNA&#x201C;) f&#xFC;r diese scheinbar nicht relevanten Sequenzen. Inzwischen haben wir gelernt, dass ein gro&#xDF;er Teil der nicht-kodierenden DNA wichtige Funktionen tr&#xE4;gt. Mindestens 9% des menschlichen Genoms sind an der Genregulation beteiligt. Das ist 9-mal mehr als proteinkodierende Sequenzen.

Organisation der Gene

Overview

The genomes of eukaryotes can be structured in several functional categories. A strand of DNA is comprised of genes and intergenic regions. ...

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genes, introns, and regulatory dna

Eukaryotic genes are arranged within DNA along with non-coding regions that help control gene activity. A DNA strand includes genes and intergenic regions, which are the stretches between genes. These regions do not code for proteins, but they can contain important regulatory elements such as promoters, enhancers, and silencers.

A gene itself is not a single continuous coding block. It usually contains protein-coding exons and non-coding introns. After DNA is transcribed into pre-mRNA in the nucleus, splicing removes the introns and joins the exons together. The shorter mRNA then moves to the cytoplasm, where it is translated into protein.

The number of introns in a gene can vary a lot. The human DMD gene is more than two million base pairs long and encodes dystrophin, a muscle protein. Mutations in DMD can cause muscular dystrophy, a disease that leads to progressive muscle deterioration. This gene has 79 exons and 103 introns. In contrast, the histone H1A gene is only 781 base pairs long and has one exon and no introns.

Introns are not always useless DNA. Some introns contain elements that help regulate genes. They also support alternative splicing, a process that mixes and matches exons after transcription. This lets one coding sequence produce several protein variants.

Most of the human genome does not code for proteins. Early genome research called many of these sequences junk DNA, but scientists now know that much of this non-coding DNA has important roles. At least 9% of the human genome is involved in gene regulation, which is far more than the protein-coding portion.

Genes, Introns, and Regulatory DNA

the dna helix

How DNA Stores Genetic Information

DNA stores genetic information that is passed from one generation to the next in organisms and most viruses. It is built from two strands of nucleotides that twist together into a double helix. The story of how scientists uncovered this structure developed step by step over nearly a century. Each DNA strand is made of nucleotides. A nucleotide contains the sugar deoxyribose, a phosphate group, and one of four nitrogen bases: adenine (A), guanine (G), cytosine (C), or thymine (T). Adenine and...

dna packaging

Chromatin and Histones in DNA Packing

Eukaryotic cells must pack long DNA molecules into the nucleus, and chromatin makes that possible. DNA wraps around proteins called histones to form nucleosomes, which are the main unit of DNA packaging. Nucleosomes then coil into compact chromatin fibers. The amount of DNA in a cell is much larger than it first seems. A single human skin cell has about 3 billion base pairs of DNA, and if that DNA were stretched out in a line, it would be about 2 meters long. With about 50 trillion cells in...

organization of genes

Eukaryotic genes are arranged within DNA along with non-coding regions that help control gene activity. A DNA strand includes genes and intergenic regions, which are the stretches between genes. These regions do not code for proteins, but they can contain important regulatory elements such as promoters, enhancers, and silencers. A gene itself is not a single continuous coding block. It usually contains protein-coding exons and non-coding introns. After DNA is transcribed into pre-mRNA in the...

karyotyping

Chromosome Stains for Detecting Disorders

Chromosome staining helps scientists find genetic disorders by showing the number and physical features of chromosomes. These features appear after DNA condenses into chromosomes during mitosis. Cytogeneticists then stop mitosis and stain the chromosomes to study their banding pattern. The pattern reveals details such as chromosome number, shape, and type. A chromosome description like this is called a karyotype. To create one, scientists take an image of the stained chromosomes and identify...

replication in prokaryotes

How Prokaryotic DNA Is Copied

Prokaryotic DNA is copied through a coordinated process with three main stages: initiation, elongation, and termination. It begins when initiator proteins bind to the single origin of replication, or ori, on the cell’s circular chromosome. The DNA then copies around the circle in both directions, starting from two replication forks, and this produces two DNA molecules. Several proteins work together to open and protect the DNA during replication. Topoisomerase cuts one side of the...

replication in eukaryotes

Eukaryotic DNA Copying and Telomeres

Eukaryotic DNA copying is tightly regulated and must duplicate many linear chromosomes before cell division. The process is highly conserved and uses many proteins with specialized roles. It moves through initiation, elongation, and termination, and it ends with two complete sets of chromosomes in the nucleus. Eukaryotic replication shares basic steps with prokaryotic DNA replication, but the larger genome and linear chromosomes require more proteins. Replication begins at multiple origins of...

proofreading

DNA Polymerase Fixes Replication Errors

DNA polymerase helps copy DNA and fix mistakes during replication. It adds nucleotides in a sequence that matches the template DNA strand. The enzyme also has a higher affinity for the correct base, which helps keep DNA replication accurate. As new genomic DNA is made, it is synthesized in the 5’ to 3’ direction. In many cells, DNA polymerases have different jobs in this process. DNA polymerase delta and DNA polymerase epsilon can proofread when nuclear DNA is being copied. These polymerases...

mismatch repair

DNA Mismatch Repair in Replication

DNA mismatch repair fixes copying errors that happen during DNA replication. When DNA polymerase makes a mistake, the cell can detect a wrong base pair, such as A with G or T with C, and replace it with the correct nucleotide. This repair system works in both prokaryotes and eukaryotes and depends on several proteins. The Mutator protein family plays a central role in this process. In bacteria such as Escherichia coli, MutS first binds the mismatch. MutL then helps identify which strand is the...

nucleotide excision repair

DNA Damage Repair by Excision

DNA damage repair by excision protects cells from mutagens that can change DNA. Exposure to environmental mutagens can create bulky lesions that bend the double helix or block transcription. If these changes are not repaired, they can lead to mutations and may contribute to cancer or disease, depending on which DNA sequences are affected. Nucleotide excision repair, or NER, is the process that detects and removes this kind of damage. Specialized proteins scan the DNA for a damaged region, then...

mutations

DNA Changes From Point Mutations to UV Damage

Mutations are changes in the DNA sequence. They can happen by chance during DNA copying, or they can be caused by environmental factors such as radiation and chemicals. Scientists also describe mutations by how much DNA they affect, how they change a protein, and whether they happen in body cells or germline cells. Some mutations affect only one nucleotide, which is a point mutation. When a point mutation falls inside a gene, the outcome depends on how the amino acid sequence changes. A silent...

transcription

Transcription and Gene Control

Transcription and gene control explain how cells make RNA from DNA and decide which genes are active. RNA polymerase copies a DNA sequence into RNA, and this is the first step in making a protein from a gene. Many other proteins and control sequences help make messenger RNA, or mRNA, correctly. In eukaryotes, the DNA is first copied into a primary RNA, also called pre-mRNA. This RNA can then be processed into mature mRNA, which serves as the template for protein synthesis. In prokaryotes such...

translation

Protein Synthesis and mRNA Decoding

Protein synthesis begins when ribosomes decode messenger RNA (mRNA) and build a chain of amino acids. This final step of gene expression is called translation. The finished chain is a polypeptide, which can later become a functional protein. Proteins are often called the building blocks of life because they make up much of the body, from muscle fibers to hairs and immune system parts. The instructions for each protein are encoded in genes found in the DNA of every cell. In biology, the central...

bacterial transformation

Griffith’s Mouse Experiment and DNA

Bacterial transformation explains how DNA can move into bacteria and change their traits. Frederick Griffith first noticed this in 1928 while studying pneumonia-causing Streptococcus pneumoniae in mice. He compared one pathogenic strain with one non-pathogenic strain and found that only the pathogenic strain killed the host mice. Griffith made an unexpected discovery when he killed the pathogenic bacteria and mixed their remains with live, non-pathogenic bacteria. The mixture killed the mice,...

key terms and concepts

Explore how eukaryotic genes are organized with exons, introns, intergenic regions, and regulatory DNA, plus how splicing and alternative splicing work.

Genes, Introns, and Regulatory DNA | JoVE K12

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The Nucleus

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Ribosomes

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Plasmodesmata

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Visualizing Onion and Cheek Cells
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Genomic DNA in Eukaryotes

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The DNA Helix

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DNA Packaging

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Chromosome Structure

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The Central Dogma

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Mutations

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Proteins: From Genes to Degradation

Students who demonstrate understanding can construct an explanation based on evidence for how the structure of DNA determines the structure of proteins which carry out the essential functions of life through systems of specialized cells.  Assessment Boundary: Assessment does not include the identification of specific cell or tissue types, whole body systems, specific protein structures and functions, or the biochemistry of protein synthesis.

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3.1.9-12.B

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3.1.9-12.C

Genes, Introns, and Regulatory DNA

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