Name: how duplicate genes shape evolution
Uploaded: 2021-04-07T12:11:59.000Z
Duration: 2 min 37 s
Channel: JoVE

K12 Standards

Louisiana Student Standards for Science

High School

Life Sciences

Biological Evolution: Unity And Diversity

HS-LS4-1

Gene Duplication and Divergence

ازدواجية الجينات هي عملية يتم فيها تكرار منطقة الحمض النووي التي ترميز الجين ، مما يؤدي إلى عمل نسخ إضافية من نفسها داخل نفس الجينوم. يمكن لهذه النسخ المكررة من الجين - التي تسمى paralogs أن تتحور وتتباعد لاحقا بإحدى الطرق التالية.
الأول هو تكوين الجينات الكاذبة. هنا ، قد يكتسب أحد المعلمات الجينية طفرات ضارة ويتحول إلى نسخة غير وظيفية تسمى الجين الكاذب.
والثاني هو الوظيفة الفرعية حيث يكتسب كل من المعلمين طفرات في مجالات ترميز البروتين المختلفة أو exons ، وبالتالي تقسيم وظيفة الجينات الأصلية بينهما. ومع ذلك ، فإن منتجات البروتين للجينين المتوازلين تكمل بعضها البعض وتظهر وظيفة الجينات الأصلية.
على سبيل المثال ، في الأسماك البدائية البحرية ، كان بروتين الغلوبين أحادي السلسلة بمثابة جزيء حامل للأكسجين في الدم.
خلال فترة التطور ، تضاعف جين الغلوبين ويعمل بشكل فرعي في جينين مختلفين قليلا لبروتينات α و β غلوبين ، والتي ترتبط بتكوين جزيء الهيموجلوبين مع 4 وحدات فرعية موجودة في معظم الفقاريات الحالية.
والثالث هو الوظيفية الجديدة. هنا ، يكتسب أحد المعلمين طفرات جديدة ومفيدة يمكن أن تؤدي إلى تطور جين جديد. في المقابل ، يحتفظ المعلمة الأخرى بالوظيفة الأصلية.
على سبيل المثال ، تضاعف جين β-globin البشري واكتساب طفرات لإنتاج جين جديد يسمى β-globin الجنيني يتم التعبير عنه حصريا في الجنين البشري. ومع ذلك ، بعد الولادة بفترة وجيزة ، يتولى جين β غلوبين إنتاج بروتينات β الغلوبين.
يعد تطور الرؤية ثلاثية الألوان لدى البشر مثالا آخر مثيرا للاهتمام على الوظائف الجديدة. قبل وقت طويل من تطور القردة الحديثة ، كان لدى الرئيسيات المبكرة رؤية ثنائية اللون بسبب وجود جينات opsin الأزرق والأخضر.
في وقت لاحق ، تضاعف جين الأوبسين الأخضر وتحول إلى جين opsin أحمر جديد.
لذلك ، فإن الأنواع التي تطورت بعد حدث الازدواجية ، مثل العالم القديم والقردة والبشر لديها ثلاثة جينات opsin تنقل رؤية ثلاثية الألوان.

<ol>
	<li>معرف PDB: 1GZX Paoli ، M. ، Liddington، R.، Tame، J. ، Wilkinson، A.، Dodson، G. (1996) التركيب البلوري للهيموجلوبين في الحالة T مع الأكسجين المرتبط في جميع أنواع الهيم. جي مول بيول 256: 775</li>
	<li value = "2" >Zhang ، Jianzhi. "التطور عن طريق ازدواجية الجينات: تحديث". الاتجاهات في علم البيئة والتطور 18 ، العدد 6 (2003): 292-298.</li>
	<li>شو ، غويشيا ، تشونس قوه ، هونغ جيان شان ، وهونغ جي كونغ. "اختلاف الجينات المكررة في بنية إكسون إنترون". وقائع الأكاديمية الوطنية للعلوم 109 ، العدد 4 (2012): 1187-1192.</li>
	<li>فاليندر ، إي جيه "التطور الجزيئي والتغيير الظاهري". (2017): 101-119.</li>
	<li>دولاي ، كانوالجيت س. ، ميراندا فون دورنوم ، جون دي مولون ، وديفيد إم هانت. "تطور رؤية الألوان ثلاثية الألوان عن طريق ازدواجية جينات opsin في العالم الجديد ورئيسيات العالم القديم." أبحاث الجينوم 9 ، العدد 7 (1999): 629-638.</li>
</ol>

ازدواج الجينات والاختلاف

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أدى العمل الأساسي الذي قام به أونو في عام 1970 إلى تعميم فكرة ازدواج الجينات وتباعدها. تكشف دراسات مقارنة تسلسل الحمض النووي أن جزءًا كبيرًا من الجينات في البكتيريا والبكتيريا العتيقة وحقيقيات النوى تم توليدها عن طريق ازدواج الجينات وتباعدها، مما يشير إلى دورها الحاسم في التطور.

تسمى النسخ المكررة من الجين Paralogs. تشكل نظائرها ذات التسلسلات والوظائف المماثلة عائلة جينية. عبر العديد من الأنواع، يتم تمييز عدد كبير من عائلات الجينات. على سبيل المثال، تضم عائلة جينات التربسين في ذبابة الفاكهة سوداء البطن أكثر من 111 عضوًا؛ تضم عائلة جينات المستقبلات الشمية في الثدييات حوالي 1000 جين عضو.

توليد الجينات المكررة

يمكن أن ينشأ ازدواج الجينات نتيجة للأسباب الأربعة التالية. أولاً، يمكن أن يؤدي العبور غير المتكافئ أثناء الانقسام الاختزالي إلى ظهور قطع DNA مكررة تحتوي على جزء من الجين أو عدة جينات.

والثاني هو انزلاق النسخ المتماثل. في حالات نادرة، أثناء تضاعف الحمض النووي، يمكن أن ينفصل إنزيم البوليميراز عن الحمض النووي ويعاد ترتيبه في موضع غير صحيح، وينسخ التسلسلات المنسوخة بالفعل مرة أخرى. يمكن لهذه العملية إنشاء نسخ مكررة من الحمض النووي على عدة مئات من القواعد.

والثالث هو النقل الرجعي. هنا، قد يتم نسخ mRNA الخلوي بشكل عكسي إلى نسخ DNA تسمى الجينات الرجعية. يمكن لهذه الجينات الرجعية أن تدخل نفسها مرة أخرى في الجينوم مما يؤدي إلى ازدواج الجينات. وبما أن النسخة المدرجة تفتقر إلى المروجين والعناصر التنظيمية الأخرى للنسخ، فإن معظم هذه النسخ المكررة تفقد وظيفتها وتصبح جينات كاذبة.

بالإضافة إلى ازدواجية الجينات، تحدث أيضًا ازدواجات كروموسومية واسعة النطاق أو ازدواجية الجينوم الكامل. قد تفشل بعض الكروموسومات في الانفصال إلى خلايا وليدة أثناء الانقسام الاختزالي، مما يؤدي إلى ظهور خلايا أحادية الصيغة الصبغية تحتوي على عدد غير طبيعي من الكروموسومات. على سبيل المثال، لدى المرضى الذين يعانون من متلازمة داون نسخة إضافية من الكروموسوم 21. وفي نباتات مثل القمح، يتم تكرار الجينوم بأكمله أكثر من ست مرات، مما يؤدي إلى تكوين سداسي الصيغة الصبغية.
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أدى العمل الأساسي ل Ohno في عام 1970 إلى تعميم فكرة ازدواجية الجينات وتباعدها. تكشف دراسات مقارنة تسلسل الحمض النووي أن جزءا كبيرا من ...

Education

JoVE Core

Molecular Biology

البيولوجيا الجزيئية

Unit 2

الوحدة الثانية

Genomes and Evolution

الجينومات والتطور

KEY TERMS AND CONCEPTS

المصطلحات والمفاهيم الأساسية

how duplicate genes shape evolution

Gene duplication helps drive evolution by creating extra copies of DNA that can change over time. The seminal work of Ohno in 1970 helped popularize this idea. DNA sequence comparisons show that many genes in bacteria, archaebacteria, and eukaryotes came from duplication and later divergence, which makes this process important in evolution.

The duplicated copies of a gene are called paralogs. When paralogs have similar sequences and functions, they form a gene family. Many gene families have been identified across species. For example, the trypsin gene family in D. melanogaster has more than 111 members, and the olfactory receptor gene family in mammals has about 1000 member genes.

Duplicate genes can form in several ways. Unequal crossing over during meiosis can create extra DNA segments that contain part of a gene or several genes. Replication slippage can also produce duplicates when DNA polymerase dissociates, realigns at the wrong spot, and copies an already made sequence again. This can create repeated DNA over several hundred bases.

Retrotransposition is another source of duplication. In this process, cellular mRNA is reverse transcribed into DNA copies called retrogenes, which can insert back into the genome. Because the inserted copy usually lacks promoters and other regulatory elements needed for transcription, most of these duplicates lose function and become pseudogenes. Large-scale chromosome duplications and whole-genome duplications can also happen. If chromosomes fail to separate during meiosis, daughter cells can end up with an abnormal number of chromosomes. Down syndrome is one example, because patients have an extra copy of chromosome 21. In plants such as wheat, the entire genome has duplicated over six times, producing a hexaploid.

How Duplicate Genes Shape Evolution

evolutionary relationships through genome comparisons

evolutionary-relationships-through-genome-comparisons

Tracing Evolution with Genome Data

Genome data helps scientists trace how organisms are related over time. When two species share a common feature, it is often encoded by DNA sequences that have stayed conserved in both species. As genome sequencing improved in the late 20th century, researchers gained a better way to compare conserved domains across species and use that evidence to infer evolutionary relationships. Genome comparison can show evolutionary relationships at three levels. At the broadest level, it highlights...

genome copying errors

DNA Replication Error Checks

DNA replication includes built-in error checks that protect the genome during cell division. Even though this process copies millions of base pairs with high fidelity, a wrong base or a longer stretch of wrong bases can still be added to the daughter strands. If these mistakes are not corrected, cells may build up mutations that can threaten survival. One level of repair is proofreading. DNA polymerase enzymes, which build the new DNA strand, can make about 1 incorrect nucleotide per 100,000...

phylogenetic trees

Reading Evolution in Phylogenetic Trees

Phylogenetic trees show how organisms are related through evolution. They map branching patterns that trace common ancestry and help scientists compare species over time. A phylogenetic tree can be read like a family tree for life. Each branch point marks a split from a shared ancestor, and the pattern of branches shows how closely related different organisms are. These trees are used to organize biological information and to study evolutionary change. They can also help scientists understand...

synteny and evolution

Chromosome Rearrangements and Synteny

Chromosome rearrangements and synteny show how shared gene order can reveal evolutionary history. Synteny means genes are found on the same chromosome, even if they are not genetically linked. John H. Renwick coined the term in 1971. Species with common ancestry often keep conserved syntenic regions. Scientists use synteny to compare the evolutionary relationship between species. Human and mouse lineages split from a common ancestor about 80 million years ago. Since then, the ancestral...

multi-species conserved sequences

Conserved DNA Across Species

Conserved DNA across species shows how some genome regions stay nearly unchanged over time. Next-generation sequencing has built large genome databases for many animals and plants. Since the Human Genome Project, scientists have compared the genomes of primates, mammals, and other distant species. These large studies have helped reveal evolutionary relationships between organisms. Although species genomes differ greatly, a few DNA sequences are highly conserved. Conserved DNA sequences found...

gene duplication and divergence

Gene duplication helps drive evolution by creating extra copies of DNA that can change over time. The seminal work of Ohno in 1970 helped popularize this idea. DNA sequence comparisons show that many genes in bacteria, archaebacteria, and eukaryotes came from duplication and later divergence, which makes this process important in evolution. The duplicated copies of a gene are called paralogs. When paralogs have similar sequences and functions, they form a gene family. Many gene families have...

exon recombination

How Exons Mix to Form New Genes

Exon recombination helps new genes form by mixing exons from the same gene or from different genes. This process is also called exon shuffling or domain shuffling. It has been seen in vertebrates, invertebrates, and some plants, including potatoes and sunflowers. During exon recombination, exons join in new exon-intron combinations. These new combinations may later become new genes. Exon shuffling follows splice frame rules, which means the exons must fit the reading frame correctly. Each...

comparing copy number variations and snps

comparing-copy-number-variations-and-snps

Genome Variation in CNVs and SNPs

Genome variation in CNVs and SNPs shows how DNA can differ across people in a population. These differences may involve a single nucleotide, which is one DNA base, or a larger chromosomal change. Scientists study them to understand inherited variation in the human genome. Copy number variations, or CNVs, are structural changes that cover more than 1 kb of DNA sequence. A CNV can change the number of copies of a gene or a group of genes. The main forms are deletion, tandem duplication,...

key terms and concepts

Learn how gene duplication creates paralogs, gene families, pseudogenes, and whole-genome changes that help shape evolution in living organisms.

How Duplicate Genes Shape Evolution | JoVE K12

molecular biology

JoVE Core Molecular Biology showcases the molecular processes of the cell through clear and concise animated video lessons. Additionally, in scientist-in-action videos, these concepts' application is demonstrated through real experiments in modern laboratories.

ohios-learning-standards-and-model-curriculum

Ohio’s Learning Standards and Model Curriculum

9-12

Biology

Evolution

Speciation

Tennessee Academic Standards

Heredity

BIO1.LS3.2

Virginia  Standards of Learning

HIgh School

BIO.5

BIO.5.d

Minnesota Academic Standards in Science

Life Science

3.2.1 9L.3.2.1.3

new-jersey-student-learning-standards-for-science

New Jersey Student Learning Standards for Science

Biological Evolution: Unity and Diversity

Arizona Science Standards

HS+B.L3

HS+B.L3U1.12

HS+B.L4

HS+B.L4U1.13

Alabama Course of Study Science

Unity and Diversity

9-12.B.4.13

south-carolina-college-and-career-ready-science-standards

South Carolina College and Career Ready Science Standards

B-LS4-1.

The DNA Helix

Deoxyribonucleic acid, or DNA, is the genetic material responsible for passing traits from generation to generation in all organisms and most viruses. DNA ...

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 ...

genome-size-and-the-evolution-of-new-genes

Genome Size and the Evolution of New Genes

Gene Families

Gene Evolution - Fast or Slow?

types-of-genetic-transfer-between-organisms

Types of Genetic Transfer Between Organisms

Evolutionary Relationships through Genome Comparisons

Genome comparison is one of the excellent ways to interpret the evolutionary relationships between organisms. The basic principle of genome comparison is ...

Genome Copying Errors

DNA replication is a well-evolved process that copies millions of base pairs with high fidelity during each cell division. Occasionally a wrong base or a ...

Phylogenetic Trees

The seminal work of Ohno in 1970 popularized the idea of gene duplication and divergence. DNA sequence comparison studies reveal that a large portion of ...

Exon Recombination

The evolution of new genes is critical for speciation. Exon recombination, also known as exon shuffling or domain shuffling, is an important means of new ...

Comparing Copy Number Variations and SNPs

Sequencing of the human genome has opened up several best-kept secrets of the genome. Scientists have identified thousands of genome variations that exist ...

Analyze and interpret scientific information that common ancestry and biological evolution are supported by multiple lines of empirical evidence. Emphasis is on a conceptual understanding of the role each line of evidence (e.g., similarities in DNA sequences, order of appearance of structure during embryological development, cladograms, homologous and vestigial structures, fossil records) demonstrates as related to common ancestry and biological evolution.

What is Natural Selection?

Natural selection is an evolutionary process in which individuals with survival-promoting traits reproduce at higher rates. These favorable traits become ...

Types of Selection

Natural selection influences the frequencies of particular alleles and phenotypes within populations in several different ways. Primarily, natural ...

Frequency-dependent Selection

When the fitness of a trait is influenced by how common it is (i.e., its frequency) relative to different traits within a population, this is referred to ...

Limits to Natural Selection

Organisms that are well-adapted to their environment are more likely to survive and reproduce. However, natural selection does not lead to perfectly ...

Natural Selection

Fitness
Widespread variation of phenotypes in natural populations provides the raw material for evolution, which is the change in the inherited traits of ...

Simulating Natural Selection
ExpandTo prepare for the lab, set out workstations for each student pair containing 6 white, 6 black, and 13 gray 12 inch ...

Simulating Natural Selection
ExpandTo begin, cut the white, black, and gray pipe cleaners into quarters, which should produce a total of 100 pieces that ...

Artificial Selection

Natural Selection and Adaptive Evolution
In natural settings, adaptive evolution takes place by natural selection, a process in which differences in ...

Observing Artificial Selection in Plants
ExpandTwo weeks before beginning the pollination experiments, collect a sufficient amount of small pots with a ...

Observing Artificial Selection in Plants 
ExpandTo begin the experiment, collect five two-week old grown plants from the generation one population that ...

Natural Selection and Adaptation

Natural selection drives evolution by supporting organisms that are best adapted to their environments, enhancing their survival and reproduction rates.
...

Natural Selection and Mating Preferences

The principle of natural selection suggests that organisms better adapted to their environment are more likely to survive and reproduce.
Evolutionary ...

What is Population Genetics?

A population is composed of members of the same species that simultaneously live and interact in the same area. When individuals in a population breed, ...

Genetic Drift

Natural selection&#x2014;probably the most well-known evolutionary mechanism&#x2014;increases the prevalence of traits that enhance survival and ...

Gene Flow

Gene flow is the transfer of genes among populations, resulting from either the dispersal of gametes or from the migration of individuals.

This ...

Construct an explanation based on evidence that biological diversity is influenced by (1) the potential for a species to increase in number, (2) the heritable genetic variation of individuals in a species due to mutation and sexual reproduction, (3) competition for limited resources, and (4) the proliferation of those organisms that are better able to survive and reproduce in the environment. Emphasis is on using evidence to explain the influence each of the four factors has on number of organisms, behaviors, morphology, or physiology in terms of ability to compete for limited resources and subsequent survival of individuals and adaptation of species. Examples of evidence could include mathematical models such as simple distribution graphs or proportional reasoning.

HS-LS4-2

Mutation, Gene Flow, and Genetic Drift

In a population that is not at Hardy-Weinberg equilibrium, the frequency of alleles changes over time. Therefore, any deviations from the five conditions ...

Hardy-Weinberg Principle

Diploid organisms have two alleles of each gene, one from each parent, in their somatic cells. Therefore, each individual contributes two alleles to the ...

Apply concepts of statistics and probability to support explanations that populations of organisms adapt when an advantageous heritable trait increases in proportion to organisms lacking this trait. Emphasis is on analyzing shifts in numerical distribution of traits and using these shifts as evidence to support explanations for adaptations. Explanations could include basic statistical or graphical analysis.

HS-LS4-3

Understanding Species and Reproductive Barriers

A species is a group of organisms that interbreed and produce fertile offspring. Typically, individuals of the same species appear similar and share ...

Formation of Species

Speciation describes the formation of one or more new species from one or sometimes multiple original species. The resulting species are discrete from the ...

Speciation Rates

Speciation can proceed at markedly different rates, and evolutionary biologists commonly describe these differences through the models of gradualism and ...

Genetics of Speciation

Speciation is the evolutionary process resulting in the formation of new, distinct species&#x2014;groups of reproductively isolated populations.The ...

Hybrid Zones

Hybrid zones are narrow regions where two closely related species interact, mate, and produce hybrids. Relative to either parent species, hybrids may ...

Extinction

The History of Life on Earth
Fossils of organisms that were different from anything alive today had been documented as early as the 17th century, but it ...

Diversity and Extinction during the Paleogene Epoch
ExpandFirst, familiarize yourself with the extinction reading supplement for the background on what ...

Diversity and Extinction during the Paleogene Epoch
ExpandBegin this procedure by reading the extinction reading supplement that has been printed out for ...

Evaluate evidence supporting claims that changes in environmental conditions can affect the distribution of traits in a population causing: (1) increases in the number of individuals of some species, (2) the emergence of new species over time, and (3) the extinction of other species. Emphasis is on determining cause and effect relationships for how changes to the environment such as deforestation, overfishing, application of fertilizers, drought, flood, and the rate of change of the environment affect distribution or disappearance of traits in species.

HS-LS4-5

How Duplicate Genes Shape Evolution

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