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

K12 Standards

Pennsylvania State Academic Standards

9-12

Life Science

Structure and Function

3.1.9-12.A

Organization of Genes

Along with the complex arrangement of genetic material in a cell&#x27;s nucleus, human genes also demonstrate their own unique organization.

Dispersed between the chromosomes are over 20,000 genes, sometimes separated by vast stretches of non-coding DNA, or that which does not encode proteins. Key to the organization of an individual gene is its promoter, to which machinery, especially RNA polymerase, can attach.

When this enzyme recognizes a nearby transcription initiation site, it begins to generate a strand of RNA, using DNA as a template. The polymerase then traverses the genetic material, and continues to yield RNA until it identifies a gene&#x27;s transcription termination sequence, stopping the process.

Importantly, between these beginning and end points lie areas called introns and exons, both of which are reflected in the RNA product. However, subsequent processes remove introns from this transcript.

Since this RNA will be used to generate proteins, exons are denoted as coding regions, whereas introns are another example of non-coding material.

Interestingly, other types of non-coding DNA like silencers also associate with genes. Proteins called repressors bind to these regions, preventing polymerase-promoter association, inhibiting transcription. As a result, silencers help to regulate gene expression.

Thus, a gene consists of various components. Among them a promoter, exons, introns, and regulatory elements, which together help to determine protein expression in a cell.

1. Williama Roya, Scotta i Waltera Gilbertów. "Ewolucja intronów spliceosomalnych: wzorce, zagadki i postęp". Nature Reviews Genetics 7, nr 3 (marzec 2006): 211–21. <a href="https://doi.org/10.1038/nrg1807">https://doi.org/10.1038/nrg1807</a>.

organizacja genów

<h4>Przegl&#x105;d</h4>

Genomy eukariont&#xF3;w mo&#x17C;na podzieli&#x107; na kilka kategorii funkcjonalnych. Ni&#x107; DNA sk&#x142;ada si&#x119; z gen&#xF3;w i region&#xF3;w mi&#x119;dzygenowych. Same geny sk&#x142;adaj&#x105; si&#x119; z ekson&#xF3;w koduj&#x105;cych bia&#x142;ka i niekoduj&#x105;cych intron&#xF3;w. Introny s&#x105; wycinane po transkrypcji sekwencji na mRNA, pozostawiaj&#x105;c jedynie eksony koduj&#x105;ce bia&#x142;ka.

<h4>Geny eukariotyczne s&#x105; oddzielone regionami mi&#x119;dzygenowymi</h4>

W genomach eukariotycznych geny s&#x105; oddzielone du&#x17C;ymi odcinkami DNA, kt&#xF3;re nie koduj&#x105; bia&#x142;ek. Jednak&#x17C;e te regiony mi&#x119;dzygenowe nios&#x105; wa&#x17C;ne elementy reguluj&#x105;ce aktywno&#x15B;&#x107; gen&#xF3;w, na przyk&#x142;ad promotor, w kt&#xF3;rym rozpoczyna si&#x119; transkrypcja, oraz wzmacniacze i t&#x142;umiki, kt&#xF3;re dostrajaj&#x105; ekspresj&#x119; gen&#xF3;w. Czasami te miejsca wi&#x105;zania mog&#x105; by&#x107; zlokalizowane daleko od powi&#x105;zanego genu.

<h4>Egzony koduj&#x105;ce bia&#x142;ka s&#x105; przeplatane intronami</h4>

Badaj&#x105;c proces transkrypcji gen&#xF3;w u eukariont&#xF3;w, badacze zdali sobie spraw&#x119;, &#x17C;e ko&#x144;cowy mRNA koduj&#x105;cy bia&#x142;ko jest kr&#xF3;tszy ni&#x17C; DNA, z kt&#xF3;rego pochodzi. Ta r&#xF3;&#x17C;nica d&#x142;ugo&#x15B;ci wynika z procesu zwanego &#x142;&#x105;czeniem. Po transkrypcji pre-mRNA z DNA w j&#x105;drze, splicing natychmiast usuwa introny i &#x142;&#x105;czy ze sob&#x105; eksony. Rezultatem jest mRNA koduj&#x105;cy bia&#x142;ko, kt&#xF3;ry przemieszcza si&#x119; do cytoplazmy i ulega translacji na bia&#x142;ko.

<h4>Liczba intron&#xF3;w na gen mo&#x17C;e si&#x119; znacznie r&#xF3;&#x17C;ni&#x107;</h4>

Jeden z najwi&#x119;kszych ludzkich gen&#xF3;w, DMD, ma d&#x142;ugo&#x15B;&#x107; ponad dw&#xF3;ch milion&#xF3;w par zasad. Gen ten koduje dystrofin&#x119; bia&#x142;ka mi&#x119;&#x15B;niowego. Mutacje w DMD powoduj&#x105; dystrofi&#x119; mi&#x119;&#x15B;ni, zaburzenie charakteryzuj&#x105;ce si&#x119; post&#x119;puj&#x105;c&#x105; degradacj&#x105; mi&#x119;&#x15B;ni. Gen ten zawiera 79 ekson&#xF3;w i 103 introny. Na drugim ko&#x144;cu spektrum znajduje si&#x119; gen histonu H1A &#x2014; jest to jeden z najmniejszych gen&#xF3;w w ludzkim genomie, maj&#x105;cy zaledwie 781 par zasad i jeden ekson i brak intron&#xF3;w.

<h4>Introny pe&#x142;ni&#x105; wa&#x17C;ne funkcje</h4>

Czy introny to &#x15B;mieciowe DNA, kt&#xF3;re nale&#x17C;y usun&#x105;&#x107;? Co ciekawe, introny mog&#x105; przenosi&#x107; elementy wa&#x17C;ne dla regulacji gen&#xF3;w. Co wi&#x119;cej, przeci&#x119;cie pocz&#x105;tkowego transkryptu i ponowne po&#x142;&#x105;czenie ekson&#xF3;w umo&#x17C;liwia przetasowanie sekwencji DNA. Ten proces mieszania i dopasowywania ekson&#xF3;w nazywany jest alternatywnym splicingiem. Umo&#x17C;liwia wytworzenie kilku wariant&#xF3;w bia&#x142;ka z jednej sekwencji koduj&#x105;cej.

<h4>Zdecydowana wi&#x119;kszo&#x15B;&#x107; ludzkiego genomu nie koduje bia&#x142;ek</h4>

Czy wiesz, &#x17C;e 99% Twojego genomu nie koduje bia&#x142;ek? Na pocz&#x105;tku bada&#x144; nad genomem biolodzy ukuli chwytliwy termin &#x2018;&#x15B;mieciowe DNA&#x2018; dla tych pozornie niefunkcjonalnych sekwencji. Tymczasem dowiedzieli&#x15B;my si&#x119;, &#x17C;e du&#x17C;a cz&#x119;&#x15B;&#x107; niekoduj&#x105;cego DNA faktycznie pe&#x142;ni wa&#x17C;ne funkcje. Co najmniej 9% ludzkiego genomu bierze udzia&#x142; w regulacji gen&#xF3;w &#x2014; czyli dziewi&#x119;&#x107; razy wi&#x119;cej ni&#x17C; sekwencje koduj&#x105;ce bia&#x142;ka.

Organizacja genów

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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Education

JoVE Core

Biology

Biologia

Genetics

Genetyka

DNA Structure and Function

Struktura i funkcje DNA

KEY TERMS AND CONCEPTS

Kluczowe terminy i pojęcia

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...

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Chromosome Stains for Detecting Disorders

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replication in prokaryotes

How Prokaryotic DNA Is Copied

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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

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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

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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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3.1.9-12.B

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3.1.9-12.C

Genes, Introns, and Regulatory DNA

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