Name: how gene families evolve and diversify
Uploaded: 2020-11-23T11:47:33.000Z
Duration: 1 min 57 s
Channel: JoVE

K12 Standards

north-carolina-k-12-science-standard-course-of-study

North Carolina K-12 Science Standard Course of Study

9-12

Biology

Biological Evolution- Unity and Diversity

LS.Bio.9.2

Gene Families

Ponieważ komórki często się dzielą, muszą również często duplikować swoje genomy. Podczas tego procesu mogą wystąpić błędy, które prowadzą do duplikacji regionów DNA. 
Jeśli zduplikowany fragment DNA zawiera jeden lub więcej regionów kodujących, nazywa się to duplikacją genu. Uwolniona od ograniczeń nałożonych na oryginalny gen w celu utrzymania funkcji, kopia genu może teraz nabywać mutacje i ewoluować, aby spełnić nową funkcję w komórce. Geny, które wyewoluowały w ten sposób - poprzez duplikację istniejących genów w genomie jednego gatunku - nazywamy "paralogami". 
Z drugiej strony ortologi to termin używany do opisania genów u różnych gatunków, które powstały od wspólnego przodka, ale nadal ewoluowały po jednym lub więcej zdarzeniach specjacyjnych. 
Termin "homolog" może być stosowany w obu przypadkach i opisuje po prostu geny o wspólnym przodku. Grupy genów homologicznych są zbiorczo określane jako "rodziny genów".
Ze względu na ich spokrewnione DNA i wynikające z tego podobieństwa białek, geny w obrębie jednej rodziny genów zazwyczaj wytwarzają białka, które pełnią podobne funkcje. 
Na przykład hemoglobina i mioglobina są pokrewnymi białkami, które wiążą tlen u ssaków. Jednak hemoglobina wyewoluowała jako podstawowa cząsteczka transportująca tlen, podczas gdy rola mioglobiny polega na magazynowaniu tlenu.
Badając sekwencje genomu, takie rodziny genów można często zidentyfikować i sklasyfikować ze względu na ich duże podobieństwo sekwencji. 
Ponadto badanie rodzin genów może pomóc w postawieniu hipotezy na temat funkcji nowo odkrytego genu nawet przy braku białka.

<ol>
	<li>1identyfikator PDB: 1GZX 
	Paoli, M., Liddington, R., Tame, J., Wilkinson, A., Dodson, G. (1996) Struktura krystaliczna hemoglobiny w stanie T z tlenem związanym we wszystkich czterech hemach. J Mol Biol 256: 775</li>
	<li>2identyfikatory PDB: 3RGK 
	Hubbard, S.R., Lambright, S.G., Boxer, S.G., Hendrickson, WA (1990) Rentgenowska struktura krystaliczna rekombinowanego ludzkiego mutanta mioglobiny w rozdzielczości 2.8 A. J Mol Biol 20: 215-218 DOI: 10.1016/S0022-2836(05)80181-0</li>
	<li>H.M. Berman, J. Westbrook, Z. Feng, G. Gilliland, T.N. Bhat, H. Weissig, I.N. Shindyalov, P.E. Bourne. (2000) Badania kwasów nukleinowych w Banku Danych o Białkach, 28: 235-242</li>
	<li>D. Sehnal, A.S. Rose, J. Kovca, S.K. Burley, S. Velankar (2018) Mol*: W kierunku wspólnej biblioteki i narzędzi do internetowej grafiki molekularnej MolVA/EuroVis Proceedings. doi:10.2312/molva.20181103</li>
	<li>S. Cheng, J. Ashley, J.. D Kurleto, M.Lobb-Rabe, Y.J. Park, R.A. Carrillo, E. Özkan (2019). Molekularne podstawy specyficzności synaptycznej receptorów nadrodziny immunoglobulin u Drosophila. eLife 2019; 8:e41028 DOI: 10.7554/eLife.41028</li>
</ol>

rodziny genowe

Rodziny genów składają się z grup, które przypuszcza się, że pochodzą od wspólnego przodka. Zazwyczaj powstają one w wyniku zdarzeń, w których gen lub geny ulegają błędnej duplikacji podczas podziału komórki. W przeciwieństwie do genów rodzicielskich (które w celu utrzymania funkcji podlegają presji selekcyjnej), te kopie genów nie muszą zachowywać swoich sekwencji i mogą ewoluować w stosunkowo szybszym tempie. Czasami regiony te można przystosować do pełnienia nowych ról w organizmie, stając się samodzielnymi nowymi genami. Kiedy to nastąpi, nazywamy te geny paralogami – dwoma genami w obrębie tego samego gatunku, które wyewoluowały ze wspólnego genu przodków. Innym powszechnym terminem odnoszącym się do członków rodziny genów jest ortolog. Geny ortologiczne to te, które powstały ze wspólnego genu przodków, ale nadal ewoluowały po jednym lub większej liczbie zdarzeń specjacyjnych. Na przykład gen mysiego enzymu trehalazy miałby u ludzi ortolog, który również wytwarza enzym trehalazę. Jednakże sekwencja tych genów i ich produktów byłaby przynajmniej częściowo różna ze względu na lata zmian ewolucyjnych od ostatniego wspólnego przodka myszy i człowieka. Dlatego są ortologami w tej samej rodzinie genów. Trzecim powszechnym terminem używanym w rodzinach genów są geny homologiczne. Termin ten jest szerszy i odnosi się do wszystkich powiązanych genów w rodzinie genów. Ponadto termin nadrodzina jest czasami używany w odniesieniu do bardzo dużych grup genów i białek, które wykazują wystarczającą homologię, aby mieć wspólnego przodka. W ich przypadku, grupowanie może opierać się na podobieństwach funkcyjnych w celu określenia zakresu grupy. W wyniku wspólnego powstania genetycznego geny w rodzinie genów zazwyczaj pełnią powiązane funkcje. Na przykład nadrodzina immunoglobulin obejmuje dużą liczbę genów kodujących zarówno białka rozpuszczalne, jak i białka powierzchniowe komórki, zaangażowane w odpowiedzi immunologiczne, takie jak wiązanie komórek lub adhezja. Kluczową cechą tej rodziny jest to, że jej członkowie mają wspólną domenę zwaną fałdem immunoglobulinowym, która ma kluczowe znaczenie dla ich funkcji.

Rodziny genowe

Rodziny genów składają się z grup genów, co do których zakłada się, że pochodzą od wspólnego przodka. Zazwyczaj powstają one w wyniku wydarzeń, w których gen lub geny ...

Education

JoVE Core

Molecular Biology

Biologia molekularna

Unit 1

Jednostka 1

DNA, Cells, and Evolution

DNA, komórki i ewolucja

KEY TERMS AND CONCEPTS

Kluczowe terminy i pojęcia

how gene families evolve and diversify

Gene families are groups of genes that are thought to come from a shared ancestor. They usually form when a gene is copied by mistake during cell division. The original gene stays under selection pressure to keep its job, while the extra copy can change more quickly over time.

Some copied genes gain a new role in the organism. When that happens, they are called paralogs, which are two genes in the same species that evolved from one common ancestral gene. Gene families also include orthologs, which are genes in different species that came from the same ancestral gene and kept evolving after speciation, or the split of one species into separate species.

A mouse trehalase gene, for example, has an ortholog in humans that also makes the trehalase enzyme. Even so, the mouse and human genes, and the proteins they produce, are not identical. They differ at least partly in sequence because of the time since mouse and human shared a common ancestor.

The term homologous genes is broader. It includes all related genes in a gene family. The term superfamily is sometimes used for very large groups of genes and proteins with enough homology, or shared ancestry, to be grouped together. For these large groups, scientists may also use shared mechanism as part of the classification.

Genes in the same family usually do related jobs. One example is the immunoglobulin superfamily. It includes many genes that code for soluble proteins and cell surface proteins involved in immune responses such as cell binding and adhesion. A key feature of this family is a shared domain called the immunoglobulin fold, which is important for function.

How Gene Families Evolve and Diversify

the dna helix

DNA Structure and Base Pairing

DNA has a helical structure that helps store genetic information. The double helix is the shape formed by two strands that twist around each other. This structure is a key feature of DNA in cells. The two strands are held together by base pairing. Bases on one strand match with bases on the other strand in a regular way. This pairing helps keep the DNA molecule stable and organized. The helix shape also helps explain how DNA fits into chromosomes and carries instructions for living things. By...

the central dogma

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prokaryotic cells

Inside Prokaryotic Cell Structure

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the tree of life - bacteria, archaea, eukaryotes

the-tree-of-life-bacteria-archaea-eukaryotes

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mutations

How Mutations Change DNA

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gene evolution - fast or slow?

Why Some Gene Regions Evolve Faster

Gene regions do not all change at the same rate. In eukaryotes, long stretches of DNA do not code for proteins or RNAs. Some of these non-coding regions include important regulatory sequences, but most have no known function. Because little or no selection pressure acts on them, they often change the fastest over evolutionary time. Protein-coding regions usually evolve more slowly. A change in a coding sequence can alter a protein and make it less effective at doing its job. That creates...

genome size and the evolution of new genes

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

How Genome Size Shapes New Genes

Genome size can vary widely, and it also helps show how new genes form. Every living organism has a genome, whether it uses RNA or DNA. Yet the size of that genome can be very different from one organism to another. One major difference is whether the organism is prokaryotic or eukaryotic. Prokaryotic genomes usually have little to no non-coding sequence, which means genes are packed closely together in operons along the chromosome. Eukaryotic genomes contain long stretches of non-coding DNA...

gene families

Gene families are groups of genes that are thought to come from a shared ancestor. They usually form when a gene is copied by mistake during cell division. The original gene stays under selection pressure to keep its job, while the extra copy can change more quickly over time. Some copied genes gain a new role in the organism. When that happens, they are called paralogs, which are two genes in the same species that evolved from one common ancestral gene. Gene families also include orthologs,...

types of genetic transfer between organisms

types-of-genetic-transfer-between-organisms

How Genes Move Within and Across Generations

Genetic transfer is the movement of genetic information from one organism to another. It happens in two main ways: vertical gene transfer and horizontal gene transfer. Vertical gene transfer moves genes from one generation to the next. It is much more common than horizontal gene transfer. Vertical gene transfer happens during both sexual reproduction and asexual reproduction. In both cases, one or more organisms pass some or all of their genome to their offspring. This kind of transfer occurs...

key terms and concepts

Learn how gene families form from duplicated genes, and how paralogs, orthologs, and homologous genes are related in evolution and function.

How Gene Families Evolve and Diversify | 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.

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

New Jersey Student Learning Standards for Science

High School

Life Science

heredity-inheritance-and-variation-of-traits

Heredity: Inheritance and Variation of Traits

HS-LS3-1

Development of Antibiotic Resistance

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Speciation Rates

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Hybrid Zones

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What is Natural Selection?

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Types of Selection

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Frequency-dependent Selection

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Limits to Natural Selection

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Natural Selection

Fitness
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Simulating Natural Selection
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Artificial Selection

Natural Selection and Adaptive Evolution
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Observing Artificial Selection in Plants
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Analyze and interpret data to summarize how various factors such as geographic isolation, pesticide resistance, antibiotic resistance can influence natural selection.

LS.Bio.9.1

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The Evidence for Evolution

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Genome Size and the Evolution of New Genes

While every living organism has a genome of some kind (be it RNA, or DNA), there is considerable variation in the sizes of these blueprints. One major ...

Gene families consist of groups of genes proposed to have originated from a common ancestor. Typically these arise through events in which a gene or genes ...

Types of Genetic Transfer Between Organisms

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Ribozymes

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Construct an explanation to illustrate how common ancestry and biological evolution are supported by multiple lines of empirical evidence.

Use models to illustrate the conditions required for natural selection, including the overproduction of offspring, inherited variation, and the struggle to survive.

LS.Bio.9.3

Construct an explanation to explain how natural selection leads to adaptations within populations.

LS.Bio.9.4

Extinction

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ExpandFirst, familiarize yourself with the extinction reading supplement for the background on what ...

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Construct explanations to illustrate how varying environmental conditions may result in: changes in the number of individuals of a species, the emergence of new species over time, or the extinction of other species.

LS.Bio.10.1

Synteny and Evolution

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Multi-species Conserved Sequences

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Taxonomy

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Phylogeny

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Use models (including dichotomous keys, scientific nomenclature, cladograms, phylogenetic trees) to identify organisms and exemplify relationships.

LS.Bio.10.2

Understand natural selection as a mechanism for biological evolution.

How Gene Families Evolve and Diversify

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