Name: genome size and gene evolution
Uploaded: 2023-04-30T18:28:42.000Z
Duration: 3 min 21 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

heredity-inheritance-and-variation-of-traits

Heredity- Inheritance and Variation of Traits

LS.Bio.6.2

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

Genome Size and the Evolution of New Genes

유전 암호의 단순한 특성에도 불구하고, 게놈 크기 측면에서는 160,000개 미만의 염기쌍인 프로테오박테리아 Candidatus Carsonella ruddii를 포함하여 알려진 가장 작은 게놈부터 약 1,500억 개의 일본 현화 식물인 Paris japonica와 같은 가장 큰 게놈에 이르기까지 상당한 차이가 있습니다. 
 
이러한 극단적인 상황에도 불구하고 박테리아와 고세균은 일반적으로 게놈 내에 약 3,000개의 유전자를 가지고 있습니다. 원핵생물은 비암호화 염기서열이 거의 없기 때문에 이는 그들의 게놈이 진핵생물에 비해 상대적으로 작을 수 있음을 의미합니다. 또한 게놈이 작다는 것은 세포 분열의 각 라운드에서 복제할 수 있는 횟수가 적다는 것을 의미하며, 이는 빠른 증식을 위한 논리학적으로 의미가 있습니다.
진핵생물은 일반적으로 20,000개의 유전자 영역 어딘가에 있지만, 이들의 게놈은 길게 뻗은 비암호화 염기서열로 구분되어 있으며, 이는 게놈 크기가 반드시 복잡성으로 변환되는 것은 아님을 의미합니다. 
파리 자포니카의 게놈은 인간 게놈의 50배가 넘을 수 있다 - 그러나 이것은 적어도 부분적으로는 방대한 양의 비암호화 염기서열과 아마도 높은 수준의 중복에 기인한다 - 반드시 더 새로운 유전자가 필요한 것은 아니다.
그렇다면 유기체는 어떻게 새로운 유전자를 진화시킬까? 대답은 일반적으로 이미 존재하는 시퀀스를 수정하는 것입니다.
새로운 유전자가 진화하기 위한 주요 자원 중 하나는 유전자 복제를 통해서입니다. 유전자를 포함하고 있는 DNA의 한 부분이 우연히 복제되었다고 상상해 보라. 이제 그 유기체는 기존 유전자의 두 번째 사본을 가지고 있다. 
이러한 새로운 유전자 사본은 기능을 유지하기 위해 원본에 가해지는 제약에서 자유롭기 때문에 발산할 수 있으며, 잠재적으로 원본의 새로운 역할이나 수정된 기능을 진화시킬 수 있습니다. 
새로운 유전자를 만드는 또 다른 방법은 DNA 셔플링(DNA shuffleling)인데, 이는 기존 유전자 또는 유전자 사본의 분절이 분리되어 다른 유전자의 분절과 결합하도록 이동하여 새로운 기능을 수행할 수 있는 하이브리드 유전자를 만드는 것입니다.
인트라제닉 돌연변이(Intragenic mutation) - 시간이 지남에 따라 돌연변이에 의해 도입된 유전자 염기서열의 변화는 많은 "새로운" 유전자를 설명합니다. 이 발산은 그 자체가 독립적으로 갈라지는 종이나 계통을 비교할 때 가장 두드러집니다. 일단 이러한 차이가 특정 지점을 넘어서거나, 한 유전자가 새로운 기능을 하게 되면, 그 유전자들은 완전히 다른 유전자로 분류될 수 있다.
마지막으로, 수평적 유전자 전달은 다른 개체 및 다른 종과 같은 외부 출처에서 새로운 유전자와 염기서열을 게놈으로 가져옵니다. 이러한 유형의 새로운 유전자 획득은 원핵생물과 고세균에서 가장 흔하며, 항생제 내성 유전자의 전달이 잘 알려진 예입니다. 
진핵생물에서는 드물지만 여전히 유전적 참신함의 필수 원천으로 간주되며 유전 물질은 이 예의 박테리아 및 곰팡이와 같이 먼 친척 종에서 올 수도 있습니다.

게놈 크기와 새로운 유전자의 진화

모든 살아있는 유기체에는 어떤 종류의 게놈(RNA 또는 DNA 등)이 있지만 이러한 청사진의 크기에는 상당한 차이가 있습니다. 게놈 크기에 영향을 미치는 주요 요인 중 하나는 유기체가 원핵생물인지 진핵생물인지 여부입니다. 원핵생물의 경우 게놈에는 비암호화 서열이 거의 또는 전혀 포함되어 있지 않으므로 유전자는 염색체를 따라 순차적으로 그룹 또는 오페론으로 밀집되어 있습니다. 반대로, 진핵생물의 유전자는 긴 비코딩 서열로 구분됩니다. 전반적으로, 이는 원핵생물의 게놈이 진핵생물의 게놈보다 평균적으로 더 작은(즉, 더 적은 수의 염기를 포함하는) 경향이 있는 현상에 기여합니다.

놀랄 것도 없이, 이러한 관찰을 고려할 때 알려진 가장 작은 게놈은 대부분 원핵생물입니다. 예를 들어 Candidatus Carsonella rudii는 게놈 크기가 16만 염기쌍에 불과한 고도로 단순화된 프로테오박테리움입니다. 생명에 필수적인 단백질을 합성하는 데 필요한 많은 유전자를 잃어버린 이 생물체는 필수 세포 내 공생체로 진화했습니다. 스펙트럼의 반대편 끝에 있는 일본의 진핵생물인 Paris japonica는 약 1,500억 염기쌍으로 알려진 가장 큰 게놈 중 하나입니다. 이의 암호화하는 유전자의 수는 알려져 있지 않지만 게놈은 엄청난 양의 중복과 비암호화 서열을 보여줍니다.

평균 원핵생물의 게놈에는 대략 3,000개의 유전자가 있습니다. 평균 진핵생물은 약 20,000개 정도입니다. 그러나 특히 진핵생물의 게놈 크기는 비암호화 서열의 양으로 인해 매우 다양합니다.

새로운 유전자의 창조

새로운 유전자를 진화시키기 위해 유기체에는 몇 가지 주요 옵션이 있습니다. 이 중 대부분의 공통점은 이미 존재하는 시퀀스를 수정한다는 것입니다.

복제는 새로운 유전자를 생성하는 데 중요한 역할을 하며, 이러한 새로운 서열을 생성할 수 있는 몇 가지 유형의 복제가 있습니다. 유전자 복제에서는 유전자를 포함하는 DNA 부분이 복제됩니다. 이 두 번째 복사본은 첫 번째 복사본을 제한하는 선택 압력을 받지 않기 때문에 갈라질 수 있습니다. 이는 시간이 지남에 따라 새로운 역할을 하는 새로운 유전자의 진화로 이어질 수 있습니다.

또 다른 유형의 복제인 DNA 셔플링(DNA shuffling)은 유전자의 일부만 복제되어 다른 유전자와 결합하는 결과를 가져올 수 있습니다. 이로 인해 새로운 제품과 함께 새로운 유전자가 생성될 수 있습니다.

때때로 새로운 유전자는 단순히 시간이 지남에 따라 축적된 돌연변이로부터 진화합니다. 이는 유전자내 돌연변이로 알려져 있으며 종 또는 다양한 개체군을 비교할 때 가장 두드러집니다.

마지막으로, 수평 유전자 전달이라고 알려진 과정을 통해 외부 소스로부터 새로운 유전자를 얻는 것도 가능합니다. 이는 유전 물질이 다른 개체, 때로는 동일한 종의 개체로부터 통합될 수 있지만 잠재적으로 완전히 다른 종의 개체로부터 통합될 수도 있음을 의미합니다. 이는 원핵생물과 고세균에서 새로운 유전자의 빈번한 공급원입니다. 진핵생물에서는 흔하지 않지만 발생하는 것으로 나타났으며, 진핵생물은 박테리아나 곰팡이처럼 먼 곳에서 유전 정보를 얻을 수도 있습니다.

모든 살아있는 유기체는 어떤 종류의 게놈(RNA 또는 DNA)을 가지고 있지만, 이러한 청사진의 크기에는 상당한 차이가 있습니다. 하나의 주요 ...

Education

교육

JoVE Core

Cell Biology

세포생물학

Unit 1

제1단원

Cells, Genomes, and Evolution

세포, 게놈, 그리고 진화

KEY TERMS AND CONCEPTS

주요 용어 및 개념

genome size and gene evolution

Genome size and gene evolution are linked through changes in DNA sequence and genome structure. Some genes can arise from parts of the genome that were not coding before, while others come from changes to existing genes. These shifts help explain how new genetic material can appear over time.

A genome is the full set of DNA in an organism. Its size can change as DNA is added, removed, or rearranged. The transcript highlights that genome size is not fixed, and that these changes can shape the evolution of new genes.

New genes may form by duplication and later change, or by other alterations in noncoding DNA. Over time, these changes can give rise to new functions. This process helps connect genome structure with the emergence of genetic novelty.

Genome Size and Gene Evolution

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

Eukaryotic cells keep their organelles separate so each part can do a specific job. Organelles such as the nucleus and mitochondria are surrounded by membranes. These membranes are selectively permeable, which means they control what enters and leaves. That control creates small internal environments with conditions suited to each organelle. These controlled spaces help organelles work more efficiently. In animal cells, lysosomes keep an acidic environment that helps their enzymes digest...

eukaryotic evolution

How Eukaryotic Cells Became Complex

Eukaryotic cells became complex through a debated evolutionary path that likely involved endosymbiosis. The most accepted model is the endosymbiont theory, which explains how organelles such as mitochondria and chloroplasts may have entered an ancestral cell. Other ideas include the nucleus-first hypothesis, the mitochondria-first hypothesis, and the eukaryote-first hypothesis. The nucleus-first hypothesis says an ancestral prokaryote first formed a membrane around its DNA, creating the...

animal and plant cell structure

Plant vs Animal Cell Division and Specialization

Plant and animal cells differ in how they divide, organize into tissues, and specialize for different jobs. Both cell types divide by mitosis in non-gametic cells and by meiosis in gametic cells, but the details are not the same. These differences help explain how each cell type supports growth and reproduction. During cell division, animal cells use centrosomes to organize spindle fibers and separate chromosomes. Plant cells do not have centrosomes. Instead, they use a microtubule-organizing...

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

How DNA Structure Was Discovered

DNA is the genetic material that passes traits from one generation to the next in organisms and most viruses. It is made of two strands of nucleotides that twist into a spring-like double helix. The shape is not perfectly even. It also has repeating grooves called the major groove and the minor groove. The major groove forms where the sugar-phosphate backbones are farther apart. This wider space gives DNA-binding proteins, including transcription factors, better access to the bases. The minor...

the central dogma

DNA to Protein: RNA’s Role

DNA to protein flow depends on RNA as the link between genetic information and the amino acids that build proteins. Early scientists knew that DNA stores the information for cell functions and that proteins carry out most of those functions. For a long time, they did not know how the code in DNA became a working protein. At first, many people thought one gene was changed directly into its protein. Two findings in eukaryotic cells challenged that idea. Protein production does not happen in the...

mutations

Mutations in DNA and Inherited Disease

Mutations are changes in the DNA sequence. They can happen on their own during DNA copying, or they can be caused by environmental factors. Scientists describe mutations in several ways, including whether they change the amino acid sequence of a protein, how much DNA they affect, and whether they occur in somatic cells or germline cells. Some mutations are point mutations. A point mutation changes a single nucleotide in DNA. Other mutations are chromosomal alterations, which change the number...

genome size and the evolution of new genes

Genome size and gene evolution are linked through changes in DNA sequence and genome structure. Some genes can arise from parts of the genome that were not coding before, while others come from changes to existing genes. These shifts help explain how new genetic material can appear over time. A genome is the full set of DNA in an organism. Its size can change as DNA is added, removed, or rearranged. The transcript highlights that genome size is not fixed, and that these changes can shape the...

gene families

Shared Origins of Gene Families

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 - fast or slow?

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.<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 genome size changes can shape gene evolution, including gene duplication, DNA rearrangement, and the rise of new genetic functions.

Genome Size and Gene Evolution | 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.

Pennsylvania State Academic Standards

Life Science

Inheritance and Variation of Traits

3.1.9-12.P

3.1.9-12.Q

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

Heredity

Mutations

Virginia  Standards of Learning

HIgh School

BIO.5

BIO.5.b

Arizona Science Standards

HS.L3

HS.L3U1.25

HS+B.L3

HS+B.L3U1.12

Next Generation Science Standards

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 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 II

Meiosis vs. Mitosis

Crossing Over

Crossing over is the exchange of genetic information between homologous chromosomes during prophase I of meiosis I. Genetic recombination gives rise to ...

Nondisjunction

Nondisjunction is the failure of homologous chromosomes or sister chromatids to separate correctly and move to the opposite poles of the cells. This ...

Spermatogenesis

Spermatogenesis is the process by which haploid sperm cells are produced in the male testes. It starts with stem cells located close to the outer rim of ...

Oogenesis

In human women, oogenesis produces one mature egg cell or ovum for every precursor cell that enters meiosis. This process differs in two unique ways from ...

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

Gastrulation establishes the three primary tissues of an embryo: the ectoderm, mesoderm, and endoderm. This developmental process relies on a series of ...

Neurulation

Neurulation is the embryological process which forms the precursors of the central nervous system and occurs after gastrulation has established the three ...

Cell Migration

Cell migration, the process by which cells move from one location to another, is essential for the proper development and viability of organisms ...

Determination

During embryogenesis, cells become progressively committed to different fates through a two-step process: specification followed by determination. ...

Use models to explain how DNA is passed from parents to offspring through the processes of meiosis and fertilization in sexual reproduction.

LS.Bio.6.1

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

Types of Genetic Transfer Between Organisms

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 ...

Overview of DNA Repair

Base Excision Repair

Nucleotide Excision Repair

DNA Distortion and Damage
Cells are regularly exposed to mutagens&#8212;factors in the environment that can damage DNA and generate mutations. UV ...

Mismatch Repair

Organisms are capable of detecting and fixing nucleotide mismatches that occur during DNA replication. This sophisticated process requires identifying the ...

Fixing Double-strand Breaks

Homologous Recombination

Gene Conversion

Restarting Stalled Replication Forks

Construct an explanation to summarize how inheritable genetic variations may result from: new genetic combinations in meiosis, mutations during replication, or mutations caused by environmental factors.

An Overview of Genetic Analysis

An organism&#8217;s physical traits, or phenotype, are a product of its genotype, which is the combination of alleles (gene variants) inherited from its ...

Genetic Crosses

To dissect genetic processes or create organisms with novel suites of traits, scientists can perform genetic crosses, or the purposeful mating of two ...

Punnett Squares

Monohybrid Crosses

Dihybrid Crosses

Trihybrid Crosses

Trihybrid Crosses
Some of Mendel&#8217;s crosses examined three pairs of contrasting characteristics. Such a cross is called a trihybrid cross. A ...

Law of Independent Assortment

Chi-square Analysis

The chi-square test is a statistical hypothesis test. It is used to check whether there is a significant difference between an expected value and an ...

Pedigree Analysis

Multiple Allele Traits

Incomplete Dominance

Gregor Mendel&#39;s work (1822 - 1884) was primarily focused on pea plants. Through his initial experiments, he determined that every gene in a diploid ...

Lethal Alleles

Agouti: A Lethal Allele
Lucien Cu&#233;not discovered lethal alleles in 1905 while studying the inheritance of coat color in mice. The agouti gene is ...

Polygenic Traits

background-and-environment-affect-phenotype

Background and Environment Affect Phenotype

Although the genetic makeup of an organism plays a major role in determining the phenotype, there are also several environmental factors, such as ...

Use mathematics and computational thinking to predict the variation and distribution of expressed traits based on: Mendelian inheritance, co-dominance, incomplete dominance, multiple alleles, and sex-linked inheritance.

LS.Bio.7.1

Overview

A pedigree is a diagram displaying a family&#x2019;s history of a trait. Analyzing pedigrees can reveal (1) whether a trait is dominant or ...

Probability Laws

Overview

The probability of inheriting a trait can be calculated using the sum and product rules. The sum rule is used to calculate the probability of ...

The Concept of Multiple Allelism

Multiple allelism describes genes that exist in three or more allelic forms. Although diploid organisms, like humans, ...

Analyze and interpret data to explain how polygenic traits result in a wide range of phenotypes.

LS.Bio.7.2

Pleiotropy

Pleiotropy is the phenomenon in which a single gene impacts multiple, seemingly unrelated phenotypic traits. For example, defects in the SOX10 gene cause ...

Nature and Nurture

Many human characteristics, like height, are shaped by both nature&mdash;in other words, by our genes&mdash;and by nurture, or our environment. For ...

Construct an explanation to summarize how traits result from interactions of genetic factors (multiple genes and/or alleles) and environmental factors.

LS.Bio.7.3

PCR: The Polymerase Chain Reaction

The polymerase chain reaction, or PCR, is a technique used to amplify DNA through thermocycling &#8211; cyles of temperature changes at fixed time ...

DNA Gel Electrophoresis

DNA gel electrophoresis is a technique used for the detection and separation of DNA molecules. An electric field is applied to a gel matrix comprised of ...

DNA Isolation

DNA isolation protocols can be fast and straightforward or complex and time-consuming depending on the type and quality of DNA required for further ...

Restriction Enzymes

Restriction enzymes are bacterial enzymes used to cut DNA in a sequence-specific manner. To cleave DNA, they bind to specific palindromic sequences called ...

Analyze and interpret data to compare DNA samples.

LS.Bio.8.1

Understand genetic mechanisms for variation.

Genome Size and Gene Evolution

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