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

Junto com o arranjo complexo de material gen&#xE9;tico no n&#xFA;cleo de uma c&#xE9;lula, os genes humanos tamb&#xE9;m demonstram sua pr&#xF3;pria organiza&#xE7;&#xE3;o &#xFA;nica. Disperso entre os cromossomas est&#xE3;o mais de 20.000 genes, &#xE0;s vezes separado por vastos trechos de DNA n&#xE3;o codificante, ou aquele que n&#xE3;o codifica prote&#xED;nas. A chave para a organiza&#xE7;&#xE3;o de um gene individual &#xE9; o seu promotor, para no qual m&#xE1;quinas, especialmente RNA polimerase, podem se anexar.Quando esta enzima reconhece um local de inicia&#xE7;&#xE3;o de transcri&#xE7;&#xE3;o pr&#xF3;ximo, come&#xE7;a a gerar uma fita de RNA, usando DNA como modelo. A polimerase ent&#xE3;o atravessa o material gen&#xE9;tico e continua a produzir RNA, at&#xE9; que ele identifique a sequ&#xEA;ncia de termina&#xE7;&#xE3;o na transcri&#xE7;&#xE3;o de um gene, parando o processo. &#xC9; importante ressaltar que entre estes pontos inicial e final encontram-se &#xE1;reas chamadas intr&#xF5;es e ex&#xF5;es, ambos sendo refletidos no produto de RNA.No entanto, subsequente os processos removem intr&#xF5;es desta transcri&#xE7;&#xE3;o. Uma vez que este RNA ser&#xE1; usado para gerar prote&#xED;nas, ex&#xF5;es s&#xE3;o denotados como regi&#xF5;es codificantes, Considerando que os intr&#xF5;es s&#xE3;o outros exemplos de material n&#xE3;o codificado. Curiosamente, outros tipos de DNA n&#xE3;o codificantes, como silenciadores, tamb&#xE9;m est&#xE3;o associados a genes.As prote&#xED;nas chamadas repressoras se ligam a essas regi&#xF5;es, impedindo a associa&#xE7;&#xE3;o do promotor da polimerase inibindo a transcri&#xE7;&#xE3;o. Como resultado, os silenciadores ajudam a regular a express&#xE3;o do gene. Assim, um gene consiste de v&#xE1;rios componentes, entre eles um promotor, ex&#xF5;es, intr&#xF5;es, e elementos regulat&#xF3;rios, que juntos ajudam a determinar a express&#xE3;o de prote&#xED;nas em uma c&#xE9;lula.

1. William Roy, Scott e Walter Gilbert. "A evolução dos íntrons spliceossômicos: padrões, quebra-cabeças e progresso." Nature Reviews Genetics 7, nº 3 (março de 2006): 211–21. <a href="https://doi.org/10.1038/nrg1807">https://doi.org/10.1038/nrg1807</a>.

organização dos genes

<h4>Vis&#xE3;o Geral</h4>
 
 Os genomas dos eucariotas podem ser estruturados em v&#xE1;rias categorias funcionais. Uma cadeia de DNA &#xE9; composta por genes e regi&#xF5;es interg&#xE9;nicas. Os genes em si consistem em ex&#xF5;es codificantes de prote&#xED;nas e intr&#xF5;es n&#xE3;o codificantes. Os intr&#xF5;es s&#xE3;o excisados assim que a sequ&#xEA;ncia &#xE9; transcrita para mRNA, deixando apenas ex&#xF5;es para codificar prote&#xED;nas.
 
 <h4>Genes Eucari&#xF3;ticos Est&#xE3;o Separados por Regi&#xF5;es Interg&#xE9;nicas</h4>
 
 Em genomas eucari&#xF3;ticos, os genes est&#xE3;o separados por grandes por&#xE7;&#xF5;es de DNA que n&#xE3;o codificam prote&#xED;nas. No entanto, essas regi&#xF5;es interg&#xE9;nicas carregam elementos importantes que regulam a atividade gen&#xE9;tica, por exemplo, o promotor onde a transcri&#xE7;&#xE3;o come&#xE7;a, e amplificadores e silenciadores que afinam a express&#xE3;o gen&#xE9;tica. Por vezes, esses locais de liga&#xE7;&#xE3;o podem estar localizados longe do gene associado.
 
 <h4>Ex&#xF5;es Codificantes de Prote&#xED;nas Est&#xE3;o Intercalados por Intr&#xF5;es</h4>
 
 Conforme os cientistas investigaram o processo de transcri&#xE7;&#xE3;o gen&#xE9;tica em eucariotas, eles perceberam que o mRNA final que codifica uma prote&#xED;na &#xE9; menor do que o DNA do qual ele &#xE9; derivado. Essa diferen&#xE7;a de comprimento deve-se a um processo chamado splicing. Assim que o pr&#xE9;-mRNA &#xE9; transcrito do DNA no n&#xFA;cleo, o splicing remove imediatamente intr&#xF5;es e junta ex&#xF5;es. O resultado &#xE9; mRNA codificante de prote&#xED;na que se move para o citoplasma e &#xE9; traduzido em prote&#xED;na.
 
 <h4>O N&#xFA;mero de Intr&#xF5;es por Gene Pode Variar Significativamente</h4>
 
 Um dos maiores genes humanos, DMD, tem mais de dois milh&#xF5;es de pares de bases. Este gene codifica a prote&#xED;na muscular distrofina. Muta&#xE7;&#xF5;es no DMD causam distrofia muscular, um dist&#xFA;rbio caracterizado pela deterioriza&#xE7;&#xE3;o muscular progressiva. Este gene cont&#xE9;m 79 ex&#xF5;es e 103 intr&#xF5;es. Na outra extremidade do espectro est&#xE1; o gene da histona H1A&#x2014;&#xE9; um dos genes mais pequenos do genoma humano com extens&#xE3;o de apenas 781 pares de bases com um ex&#xE3;o e nenhum intr&#xE3;o.
 
 <h4>Os Intr&#xF5;es Carregam Fun&#xE7;&#xF5;es Importantes</h4>
 
 Os intr&#xF5;es s&#xE3;o lixo do DNA que precisa ser removido? Curiosamente, os intr&#xF5;es podem carregar elementos que s&#xE3;o importantes para a regula&#xE7;&#xE3;o gen&#xE9;tica. Al&#xE9;m disso, a excis&#xE3;o inicial da transcri&#xE7;&#xE3;o e a jun&#xE7;&#xE3;o de ex&#xF5;es permite que sequ&#xEA;ncias de DNA sejam misturadas. Este processo de mistura e combina&#xE7;&#xE3;o de ex&#xF5;es &#xE9; conhecido como splicing alternativo. Torna poss&#xED;vel produzir v&#xE1;rias variantes proteicas a partir de uma &#xFA;nica sequ&#xEA;ncia de codifica&#xE7;&#xE3;o.
 
 <h4>A Grande Maioria do Genoma Humano N&#xE3;o Codifica Prote&#xED;nas</h4>
 
 Sabia que 99% do seu genoma n&#xE3;o codifica prote&#xED;nas? Nos primeiros tempos de investiga&#xE7;&#xE3;o do genoma, os bi&#xF3;logos cunharam o termo &#x2018;DNA lixo&#x2019; para essas sequ&#xEA;ncias aparentemente n&#xE3;o funcionais. Entretanto, aprendemos que uma grande parte do DNA n&#xE3;o codificante tem fun&#xE7;&#xF5;es importantes. Pelo menos 9% do genoma humano est&#xE1; envolvido na regula&#xE7;&#xE3;o gen&#xE9;tica&#x2014;isso &#xE9; nove vezes mais do que sequ&#xEA;ncias de codifica&#xE7;&#xE3;o de prote&#xED;nas.

Organização dos Genes

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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Biology

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Genética

DNA Structure and Function

Estrutura e Função do DNA

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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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A coleção JoVE Core dá vida à biologia através de mais de 300 vídeos de animação concisos e fáceis de entender que explicam conceitos-chave de biologia, além de mais de 150 vídeos de Cientistas em ação que mostram experimentos reais em pesquisa realizados nos laboratórios atualmente.

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New Jersey Student Learning Standards for Science

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What are Cells?

Cells are the smallest and basic units of life, whether it is a single cell that forms the entire organism, e.g., in a bacterium or trillions of them, ...

Cell Size

Cell sizes vary widely among and within organisms. Bacterial cells range between 1-10 micrometers (&#x3BC;m)and are considerably smaller than most ...

Eukaryotic Compartmentalization

One of the distinguishing features of eukaryotic cells is that they contain membrane-bound organelles, such as the nucleus and mitochondria, that carry ...

Prokaryotic Cells

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Cytoplasm

The cytoplasm consists of organelles and a framework of protein scaffolds called the cytoskeleton suspended in an aqueous solution, the cytosol. The ...

The Nucleus

The nucleus is a membrane-bound organelle that acts as a control center in a eukaryotic cell. It contains chromosomal DNA, which controls gene expression ...

Endoplasmic Reticulum

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Ribosomes

Ribosomes translate genetic information encoded by messenger RNA (mRNA) into proteins. Both prokaryotic and eukaryotic cells have ribosomes. Cells that ...

Golgi Apparatus

As they leave the Endoplasmic Reticulum (ER), properly folded and assembled proteins are selectively packaged into vesicles. These vesicles are ...

Lysosomes

Lysosomes are membrane-enclosed spherical sacs derived from the Golgi apparatus. The most important function of the lysosome is degrading macromolecules ...

Peroxisomes

Peroxisomes and mitochondria are two important oxygen-utilizing organelles in eukaryotic cells. Mitochondria carry out cellular respiration&#x2014;the ...

Introduction to the Cytoskeleton

Overview of the Cytoskeleton
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Introduction to Actin

Actin is a highly conserved cytoskeletal protein found abundantly in eukaryotic cells. It constitutes 10% weight of the total cellular protein in muscle ...

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Overview of Myosin Structure and Function

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Microtubules are the thickest cytoskeletal filaments with a diameter of 25 nm. In prokaryotic organisms, microtubules are commonly found in locomotory ...

The Structure of Intermediate Filaments

The intermediate filaments are one of three widely studied cytoskeletal filaments. They are so named as their diameter (10 nm) is in between that of ...

Types of Intermediate Filaments

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Plant Cell Wall

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Plasmodesmata

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Cell Structure

Background
Cells represent the most basic biological units of all organisms, whether it be simple, single-celled organisms like bacteria, or large, ...

Visualizing Onion and Cheek Cells
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Genomic DNA in Prokaryotes

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Binary Fission

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Genomic DNA in Eukaryotes

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The DNA Helix

Overview

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DNA as a Genetic Template

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DNA Packaging

Overview

Eukaryotes have large genomes compared to prokaryotes. In order to fit their genomes into a cell, eukaryotes must pack their DNA tightly inside ...

Chromosome Structure

A functional eukaryotic chromosome must contain three elements: a centromere, telomeres, and numerous origins of replication.
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The Central Dogma

The central dogma explains the flow of genetic information from DNA nucleotides to the amino acid sequence of proteins.
RNA is the Missing Link Between ...

Mutations

Mutations are changes in the sequence of DNA. These changes can occur spontaneously or they can be induced by exposure to environmental factors. Mutations ...

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.

Characteristics of Life

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Phylogeny

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Students who demonstrate understanding can develop and use a model to illustrate the hierarchical organization of interacting systems that provide specific functions within multicellular organisms.  Assessment Boundary: Assessment does not include interactions and functions at the molecular or chemical reaction levels.

3.1.9-12.B

Functions of Life

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Negative and Positive Feedback

Homeostatic Imbalance

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3.1.9-12.C

Genes, Introns, and Regulatory DNA

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