Name: gene evolution rates and selection
Uploaded: 2023-04-30T18:28:42.000Z
Duration: 2 min 5 s
Channel: JoVE

K12 Standards

Pennsylvania State Academic Standards

9-12

Life Science

Inheritance and Variation of Traits

3.1.9-12.Q

Gene Evolution - Fast or Slow?

The way that mutations affect the survival of a cell depends greatly on the location of the genetic change. In regions of the genome that do not code for genes or regulatory regions, mutations may have little effect, such that the cell can often continue as usual.
The overall effect is that non-coding sequences are free to change fairly rapidly in evolutionary terms, meaning these regions of a genome may be almost unrecognizable even in two closely related species.
However, in coding sequences, mutations are not so freely adopted. While in very rare cases they may be beneficial, such as a mutation in a gene for an enzyme creating a better binding affinity for the substrate; the majority will be detrimental.
Let&#8217;s look at the 16s rRNA gene, for example. It encodes a structural RNA forming part of the ribosome. Some of the regions of this RNA are critical to ribosome function, and changes in these segments are exceptionally rare. These highly conserved regions change so slowly that they can be used to examine sequence homology across phyla, kingdoms, and even all living species - making them a valuable tool for studying relationships between even distantly related organisms.
However, there are still sections of the 16s rRNA sequence less critical to function, which may evolve slightly faster. These &#8220;variable regions&#8221; can be useful for elucidating relationships between more closely related species &#8211; such as genera or even strains of bacteria.
Overall, this leads to the phenomenon that different genome regions may evolve at vastly different rates, even within regions encoding a single gene.

gene evolution - fast or slow?

De genomen van eukaryoten worden onderbroken doorbevatten lange stukken sequentie sequenties die niet coderen voor geen eiwitten of RNA's.RNA’s coderen. Hoewel sommige van deze regio'sregio’s cruciale regulerenderegelgevende sequenties bevatten, heeft dehet overgrote meerderheiddeel van dit DNA geen bekende functie. Typisch zijn Evolutie vindt doorgaans het snelst plaats in deze regio's van het genoom de regio's waarin de snelste verandering, in evolutionaire termen, wordt waargenomenniet-coderende regio’s, omdat er doorgaans weinig tot geen selectiedruk op deze regio's inwerkt om hunis die de sequenties te behoudenstabiliseert.

Regio's die coderen voor een eiwit kunnen daarentegen een Daarentegen kunnen coderende regio’s van het genoom, die eiwitten produceren, onder hoge selectiedruk ervaren, omdat eventuele veranderingen in hun sequentie waarschijnlijk zullen resulteren in staan. Veranderingen in deze sequenties kunnen leiden tot een eiwit dat minder goed in staat is zijn functie optimaal uit te voeren. Af en toe zal een mutatie in een van functioneert. Toch kunnen mutaties in deze regio's echter resulteren in regio’s soms een gunstig resultaat effect hebben dat bijdraagt aan de algehele fitheidoverlevingskans van heteen organisme, en dergelijke. Zulke mutaties blijven vaak bestaanbehouden en kunnen zich zelfs in populaties worden vastgelegd. Wanneer de frequentie van deze mutatiegebeurtenissen wordt vergelekeneen populatie vastzetten. In vergelijking met de relatief regelmatige veranderingen die worden waargenomen in niet-coderende sequenties, is dit buitengewoon regio’s zijn zulke nuttige mutaties echter zeldzaam, en daarom wordt in . Daarom worden coderende regio’s over het algemeen aangenomen dat coderende regio's langzaam evoluerenals traag evoluerend beschouwd.

Het is ook waar dat Bovendien bestaat er een meetbare hoeveelheidbinnen coderende sequenties zelf variatie bestaat in de niveausmate van sequentiebehoud binnen coderende sequenties, en dit is . Dit is te zien bij alle organismen waarneembaar.. Neem bijvoorbeeld het voorbeeld van een receptoreiwitreceptor-eiwit. Dergelijke eiwitten hebben doorgaansvaak verschillende regio's die functies kunnen vervullen zoals ligandbinding, of intracellulaire signalering, of membraanintegratie. In dit gevalfunctionele domeinen, zoals een ligandbindend domein, een intracellulair signaalgebied en een membraanintegratiegedeelte. Een mutatie in het ligandbindende domein kan een mutatie in de regio die betrokken is bij ligandbinding een ervoor zorgen dat het eiwit produceren dat minder efficiënt is in het binden vanaan het ligand. Daarom bindt. Hierdoor zou de selectiedruk waarschijnlijk hoog zijn op de specifiekeop de nucleotiden die voor dit deel van het eiwit coderen. In het hoog zijn. Daarentegen zou een mutatie in het membraanoverspannende gedeelte van het eiwit dat het membraan overspant, kan er echtermogelijk minder effect worden waargenomen als er een aminozuursubstitutie plaatsvindt, en dus een lager niveau van hebben, waardoor de selectiedruk. Onder deze omstandigheden zouden we kunnen zien dat twee regio's van op dit gebied lager zou zijn. In zulke gevallen kunnen verschillende regio’s binnen hetzelfde eiwitcoderendecoderende gen verschillende evolutiesnelheden kunnen hebben.

Sequencing van genen of genomische regio's om fylogenieën op te bouwen

Gen- en genoomsequencing voor fylogenetische analyse

Deze variatie in de snelheid van de evolutie evolutiesnelheid binnen verschillende delen van het genoom over verschillende regio's kan worden bestudeerd om vragen over evolutionaire relaties te beantwoorden. Genen en genregio's kunnen worden geselecteerd en gesequenced over groepenDoor bepaalde genen of genomische regio’s te selecteren en te sequencen bij verschillende individuen om, kunnen onderzoekers vragen te beantwoorden die zo beperkt zijn alsvariërend van "zijn deze populaties potentieelmogelijk verschillende soorten?" of zo breed als “tot "hoe plaatsenpassen deze phyla zichfyla in de boom des levens?”. van het leven?".

Voor de eerste zou het selecteren van vraag kan een gen met een relatief lichtweinig geconserveerde regioregio’s helpen om verschillen op populatieniveau tussen populaties te identificeren. OmVoor bredere fylogenetische vragen over groepen zo divers alsverschillende fyla te beantwoorden, kan daarentegen een sterk geconserveerd gengebied daarentegengeconserveerde genregio voldoende homologie biedenbevatten om een fylogenie van dergelijke groepenfylogenetische stamboom op te produceren. bouwen.

Veelgebruikte regio'sgenetische markers voor moleculaire fylogenetische analyses zoals deze omvatten zijn ribosomale rRNA-genen (, zoals 16s16S rRNA, 18s18S rRNA of 28sen 28S rRNA), of, evenals genomische regio'sregio’s die bekend staanbekendstaan als ITS (Internal Transcribed Spacers, I ofen II) en), die zich tussen de ribosomale rRNA-subeenheidsubunitgenen bevinden (genen)..

The genomes of eukaryotes are punctuated by long stretches of sequence which do not code for proteins or RNAs. Although some of these regions do contain ...

Education

JoVE Core

Cell Biology

Celbiologie

Unit 1

Eenheid 1

Cells, Genomes, and Evolution

Cellen, genomen en evolutie

KEY TERMS AND CONCEPTS

BELANGRIJKE TERMEN EN CONCEPTEN

Genenevolutie - Snel of Langzaam?

gene evolution rates and selection

Gene evolution can happen at different rates, and natural selection helps shape those changes. Some genes change slowly because important DNA changes are removed over time. Other genes can change more quickly when different mutations are kept in a population.

The rate of evolution depends on how a gene is used and how strongly it is affected by selection. Genes with essential jobs often stay more similar across species. Genes under weaker pressure may show more variation and may evolve faster.

Comparing gene sequences helps scientists see these patterns over time. These comparisons can show which regions are conserved and which regions have changed more rapidly. That information helps explain how genes evolve in different lineages.

Gene Evolution Rates and Selection

what are cells?

Cells as the Building Blocks of Life

Cells are the basic building blocks of life. A bacterium can be a single cell, while a human is made of trillions of cells. Even with this range, cells share key features that support life. A living cell has a plasma membrane. This is a bilayer of lipids that separates the cytoplasm inside the cell from the outside environment. A cell also carries genetic information in the form of DNA. In prokaryotic cells, DNA is found in a region called the nucleoid. In eukaryotic cells, DNA is enclosed...

the tree of life - bacteria, archaea, and eukaryotes

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

Three Domains on the Tree of Life

The tree of life shows how living things are grouped into three domains: Bacteria, Archaea, and Eukaryotes. This classification helps explain the major branches of life and how they are related. Bacteria and Archaea are both single-celled organisms, but they are not the same. Eukaryotes include organisms with more complex cells, such as plants, animals, and fungi. Together, these three domains give a broad picture of life on Earth. Understanding the tree of life helps students compare cell...

prokaryotic cells

How Prokaryotes Survive Without a Nucleus

Prokaryotes are small unicellular organisms that live without a nucleus. They include the domains Archaea and Bacteria. Bacteria include common microbes such as Salmonella and E. coli, while Archaea include extremophiles that live in harsh places like volcanic springs. Prokaryotic cells still share several basic features with eukaryotic cells. They have a plasma membrane, cytoplasm, ribosomes, and genetic material in the form of single, circular DNA. Their cell parts float freely in the...

eukaryotic compartmentalization

How Organelles Keep Cells Working

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eukaryotic evolution

How Eukaryotic Cells Became Complex

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animal and plant cell structure

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cytoplasm

Cytoplasm and the Cell’s Internal Support

The cytoplasm is the cell’s internal space that holds organelles and the cytoskeleton. It is suspended in the cytosol, an aqueous fluid made of water, ions, salts, and many organic molecules. This fluid helps keep the cell organized and supports many cellular activities. The cytoplasm is also where protein synthesis and protein folding take place. The watery cytosol helps proteins fold correctly. In a folded protein, hydrophobic amino acid side chains tend to stay buried in the core, while...

the nucleus

Nuclear DNA, Chromatin, and Nucleoli

The nucleus is a membrane-bound organelle that stores chromosomal DNA and helps control what proteins a eukaryotic cell makes. It acts as the cell’s control center. DNA in mitochondria and chloroplasts is different because it mainly supports functions specific to those organelles. Inside the nucleus, DNA is wrapped around proteins called histones. This DNA-protein complex is called chromatin. During interphase, when the cell is not dividing, chromatin stays loosely arranged so the DNA is easy...

the dna helix

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the central dogma

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mutations

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Genome Size and Gene Evolution

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gene families

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Gene families are groups of related genes that share a common origin. They form when genes are copied and then change over time. These related genes can be found within the same genome. The video also connects gene families to homologous genes and orthologous genes. Homologous genes are genes with a shared evolutionary origin. Orthologous genes are homologous genes found in different species. Gene families help show how these relationships are used to study evolution and related gene functions.

Gene evolution can happen at different rates, and natural selection helps shape those changes. Some genes change slowly because important DNA changes are removed over time. Other genes can change more quickly when different mutations are kept in a population. The rate of evolution depends on how a gene is used and how strongly it is affected by selection. Genes with essential jobs often stay more similar across species. Genes under weaker pressure may show more variation and may evolve faster.<br...

types of genetic transfer between organisms

types-of-genetic-transfer-between-organisms

Vertical and Horizontal Gene Transfer

Genetic transfer between organisms happens in two main ways: vertical gene transfer and horizontal gene transfer. These two routes explain how hereditary material moves from one generation to the next or between organisms that are not parent and offspring. Vertical gene transfer passes genes from parent to offspring during reproduction. This is the usual way genetic information is inherited in living things. Horizontal gene transfer moves genetic material between organisms outside of...

key terms and concepts

Explore how natural selection affects gene evolution rates, from slowly changing conserved genes to faster-changing genes with more variation.

Gene Evolution Rates and Selection | JoVE K12

cell biology

JoVE Core Cell Biology illustrates complex cellular processes in easy-to-understand yet comprehensive animated video lessons. This collection focuses on the essential components and functions of cells, including organelles and membranes, cellular transport, and cell energetics. It is complemented by scientist-in-action videos that demonstrate the application of cell biology in real-world research experiments.

Louisiana Student Standards for Science

High School

Life Sciences

Biological Evolution: Unity And Diversity

HS-LS4-1

ohios-learning-standards-and-model-curriculum

Ohio’s Learning Standards and Model Curriculum

Biology

Heredity

Mutations

Virginia  Standards of Learning

HIgh School

BIO.5

BIO.5.b

Next Generation Science Standards

heredity-inheritance-and-variation-of-traits

Heredity: Inheritance and Variation of Traits

HS-LS3-2

new-york-state-science-learning-standards

New York State Science Learning Standards

HS-LS3-1.

What is the Cell Cycle?

The cell cycle refers to the sequence of events occurring throughout a typical cell&#8217;s life. In eukaryotic cells, the somatic cell cycle has two ...

Interphase

The cell cycle occurs over approximately 24 hours (in a typical human cell) and in two distinct stages: interphase, which includes three phases of the ...

The Cell Cycle Control System

Positive Regulator Molecules

Inhibition of CDK Activity

Mitosis and Cytokinesis

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Chromosome Duplication

Cohesins

Condensins

The Mitotic Spindle

Centrosome Duplication

Spindle Assembly

Attachment of Sister Chromatids

Forces Acting on Chromosomes

Separation of Sister Chromatids

The Spindle Assembly Checkpoint

Anaphase A and B

Anaphase Promoting Complex

The Contractile Ring

Determining the Plane of Cell Division

The Phragmoplast

Distribution of Cytoplasmic Content

An Introduction to Cell Division

Cell division is the process by which a parent cell divides and gives rise to two or more daughter cells. It is a means of reproduction for single-cell ...

Cell Cycle Analysis

Cell cycle refers to the set of events through which a cell grows, replicates its genome, and ultimately divides into two daughter cells through the ...

Live Cell Imaging of Mitosis

Mitosis is a form of cell division in which a cell&#8217;s genetic material is divided equally between two daughter cells. Mitosis can be broken down into ...

Fertilization

During fertilization, an egg and sperm cell fuse to create a new diploid structure. In humans, the process occurs once the egg has been released from the ...

Cleavage and Blastulation

After a large-single-celled zygote is produced via fertilization, the process of cleavage occurs while zygotes travel through the uterine tube. Cleavage ...

Gastrulation

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Neurulation

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an-introduction-to-developmental-genetics

An Introduction to Developmental Genetics

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An Introduction to Organogenesis

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Fate Mapping

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Students who demonstrate understanding can use a model to illustrate the role of cellular division (mitosis) and differentiation in producing and maintaining complex organisms.  Assessment Boundary: Assessment does not include specific gene control mechanisms or rote memorization of the steps of mitosis.

3.1.9-12.D

DNA Packaging

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Organization of Genes

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Chromosome Structure

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The centromere is a DNA ...

Chromosome Replication

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The Nucleosome

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Nucleosome Remodeling

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Chromatin Packaging

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Karyotyping

Proteins: From Genes to Degradation

The DNA Helix

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The Central Dogma

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RNA is the Missing Link Between ...

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

Gene Families

Students who demonstrate understanding can ask questions to clarify relationships about the role of DNA and chromosomes in coding the instructions for characteristic traits passed from parents to offspring. Assessment Boundary: Assessment does not include the phases of meiosis or the biochemical mechanism of specific steps in the process.

3.1.9-12.P

Genomic DNA in Prokaryotes

The genome of most prokaryotic organisms consists of double-stranded DNA organized into one circular chromosome in a region of cytoplasm called the ...

Binary Fission

Fission is the division of a single entity into two or more parts, which regenerate into separate entities that resemble the original. Organisms in the ...

Genomic DNA in Eukaryotes

Eukaryotes have large genomes compared to prokaryotes. To fit their genomes into a cell, eukaryotic DNA is packaged extraordinarily tightly inside the ...

What is Meiosis?

Meiosis is the process by which diploid cells divide to produce haploid daughter cells. In humans, each diploid cell contains 46 chromosomes, half from ...

Meiosis I

Meiosis is a carefully orchestrated set of cell divisions, the goal of which&#x2014;in humans&#x2014;is to produce haploid sperm or eggs, each containing ...

Meiosis II

Meiosis II is the second and final stage of meiosis. It relies on the haploid cells produced during meiosis I, each of which contain only 23 ...

Crossing Over

Unlike mitosis, meiosis aims for genetic diversity in its creation of haploid gametes. Dividing germ cells first begin this process in prophase I, where ...

Nondisjunction

During meiosis, chromosomes occasionally separate improperly. This occurs due to failure of homologous chromosome separation during meiosis I or failed ...

Base-pairing and DNA Repair

The DNA Replication Fork

Lagging Strand Synthesis

The Replisome

Proofreading

Synthesis of new DNA molecules is carried out by the enzyme DNA polymerase, which adds nucleotides on the daughter strand complementary to the template ...

Replication in Prokaryotes

DNA replication has three main steps: initiation, elongation, and termination. Replication in prokaryotes begins when initiator proteins bind to the ...

Replication in Eukaryotes

In eukaryotic cells, DNA replication is highly conserved and tightly regulated. Multiple linear chromosomes must be duplicated with high fidelity before ...

Students who demonstrate understanding can make and defend a claim based on evidence that inheritable genetic variations may result from (1) new genetic combinations through meiosis, (2) viable errors occurring during replication, and/or (3) mutations caused by environmental factors. Assessment Boundary: Assessment does not include the phases of meiosis or the biochemical mechanism of specific steps in the process.

Gene Evolution Rates and Selection

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