Name: how life is classified into three domains
Uploaded: 2020-11-23T11:47:33.000Z
Duration: 2 min 40 s
Channel: JoVE

K12 Standards

Next Generation Science Standards

High School

Life Science

heredity-inheritance-and-variation-of-traits

Heredity: Inheritance and Variation of Traits

HS-LS4-1

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

The Tree of Life - Bacteria, Archaea, Eukaryotes

Charles Darwin famously compared the evolutionary relationships between different species to the branches of a tree, all originating from a common ancestor.
Historically, an organism&#8217;s position on the tree was simply determined based upon its observable characteristics or phenotype, such as the presence of leaves, a spine, or eyes.
Extinct species could be placed on the tree in a similar fashion &#8211; using phenotypic traits preserved in the fossil record.
Shortly after Darwin published On the Origin of Species, Haeckel proposed three &#8216;kingdoms&#8217; of life in 1866, plants, animals, and protists &#8211; which were neither plant nor animal - based on easily observable phenotypes.
Eventually, the distinction between plants and animals was found to be less important than previously proposed.
Thus, in 1937, the tree of life evolved to contain two large &#8216;empires&#8217; &#8211; the eukaryotes with membrane-bound nuclei and the prokaryotes without.
This paradigm, however, resulted in some difficulty when it came to placing prokaryotes on the tree: one rod-shaped microbe is phenotypically hard to distinguish from another.
Advancements in genetic analysis, particularly 16S rRNA sequencing, soon toppled this tree when organisms traditionally classed together as prokaryotes were found to have genetically divergent evolutionary origins.
So, the tree of life evolved once more in 1990 and the prokaryotes were divided into two domains - giving us the three domains of the modern tree of life: bacteria, archaea, and eukaryotes.
The first of these domains, bacteria, consists of unicellular, prokaryotic organisms that lack a membrane-bound nucleus.
The next domain, archaea, is also made up of unicellular, prokaryotic organisms distinguished from bacteria by their unique evolutionary history.
Finally, the eukaryotes consist of uni- and multicellular organisms distinguished by their membrane-bound nucleus. This domain includes fungi, plants, and animals.
The evolutionary tree of life, much like an actual tree, is a &#8216;living&#8217; metaphor and the classification of many organisms, even the distinction between archaea and bacteria, is often contested and occasionally changed.

the tree of life - bacteria, archaea, eukaryotes

The &#8220;tree of life&#8221; describes the evolution of life and the evolutionary relationships between organisms. The root of the tree is the common ancestor to all life on Earth. All other species radiate from this point, much like the branches of a tree. The numerous tips of these branches on the tree of life represent every living, or extant, species. Extinct species, which are species that no longer exist, can be found towards the center of the tree. Currently, these organisms, both extant and extinct, are organized into three domains: bacteria, archaea, and eukaryotes. However, the distinctions between these domains and the classification of organisms is debated continuously, resulting in a &#8216;living&#8217; tree of life that changes as more information is uncovered.
The History of the Tree of Life 
The tree of life, itself, has evolved, much like the organisms it contains. Shortly after Charles Darwin published On the Origin of Species in 1859, Ernst Haeckel proposed three &#8220;kingdoms&#8221; of life: plants, animals, and protists - which were simply organisms that were neither plant nor animal. The distinctions between these kingdoms were based entirely on easily observable phenotypes.
In 1937&#160;Edouard Chatton divided the tree of life into two vast &#8216;empires&#8217; instead: eukaryotes and prokaryotes. Simply put, the eukaryotes possessed membrane-bound nuclei, and the prokaryotes did not. During the 1970&#8217;s, Woese found that a group under the bacteria classification, called archaea, differed from the bacteria in several ways: an absence of peptidoglycan in their cell walls, differences in coenzymes, and differences in their 16S rRNA gene sequence. All of these differences suggested that archaea originated from a line of descent separate from bacteria.
The Three Domains of Life
The modern tree of life consists of three &#8216;branches&#8217;: bacteria, archaea, and eukaryotes. The domain bacteria consists of unicellular, prokaryotic organisms that lack a membrane-bound nucleus. Bacteria can take many shapes, from spherical cocci to rod-shaped bacilli. Members of this domain are found in almost every place on Earth, including on and in the human body.
Similar to bacteria, archaea are also unicellular, prokaryotic organisms. Phenotypically, archaea are very difficult to differentiate from bacteria. At the molecular level, archaea resemble eukaryotes in terms of their machinery for replication, transcription, and translation. However, archaea resemble bacteria in terms of metabolism and energy conversion. Archaea are often found in the most inhospitable of habitats: bogs, wastewater treatment plants, the deepest parts of the ocean, and hot acid springs.

The &#8220;tree of life&#8221; describes the evolution of life and the evolutionary relationships between organisms. The root of the tree is the common ...

Education

JoVE Core

Molecular Biology

Unit 1

DNA, Cells, and Evolution

KEY TERMS AND CONCEPTS

how life is classified into three domains

The tree of life shows how organisms are related through evolution. Its root represents the common ancestor of all life on Earth. From that point, branches spread out like a tree. The tips of the branches represent living, or extant, species. Species that no longer exist, called extinct species, appear closer to the center of the tree. Today, these organisms are grouped into three domains: bacteria, archaea, and eukaryotes. Scientists still debate these divisions, so the tree of life keeps changing as new information is found.

The idea of the tree of life has changed over time. After Charles Darwin published On the Origin of Species in 1859, Ernst Haeckel suggested three kingdoms of life: plants, animals, and protists. Protists were organisms that were neither plant nor animal. These early groups were based on visible traits. In 1937, Edouard Chatton divided life into two large empires instead: eukaryotes and prokaryotes. Eukaryotes have membrane-bound nuclei, while prokaryotes do not.

In the 1970s, Woese showed that archaea were different from bacteria in several important ways. Archaea lack peptidoglycan in their cell walls. They also differ in coenzymes and in their 16S rRNA gene sequence. These findings suggested that archaea came from a separate line of descent, not from bacteria.

The modern tree of life includes bacteria, archaea, and eukaryotes. Bacteria are unicellular prokaryotes, which means they are single-celled organisms without a membrane-bound nucleus. They can have many shapes, including spherical cocci and rod-shaped bacilli. Bacteria live in almost every environment on Earth, including on and in the human body.

Archaea are also unicellular prokaryotes, and they can be hard to tell apart from bacteria by appearance alone. At the molecular level, archaea resemble eukaryotes in replication, transcription, and translation. They resemble bacteria in metabolism and energy conversion. Archaea are often found in harsh habitats such as bogs, wastewater treatment plants, the deepest parts of the ocean, and hot acid springs.

How Life Is Classified Into Three Domains

how-life-is-classified-into-three-domains

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

DNA to Protein: Central Dogma Steps

The central dogma explains how genetic information moves from DNA to RNA to protein. This flow is a key idea in molecular biology. It helps show how cells use genes to make the molecules that carry out work. DNA stores the instructions for making proteins. During transcription, a gene in DNA is copied into RNA. The RNA then carries that message to the next stage. In translation, the RNA message is used to build a protein. Proteins do much of the cell’s work, so this process connects genes to...

prokaryotic cells

Inside Prokaryotic Cell Structure

Prokaryotic cells have a simple internal structure compared with many other cells. They are usually divided into two groups: bacteria and archaea. These cells have no nucleus, so their DNA is not enclosed in a membrane-bound compartment. Instead, the genetic material is found in the nucleoid, a region where the DNA is located in the cell. Some prokaryotic cells also contain plasmids, which are small extra DNA molecules. A capsule may surround the cell and provide an additional outer layer. <br...

eukaryotic compartmentalization

Cell Compartments in Eukaryotes

Eukaryotic cells use compartments to organize many different jobs inside one cell. These compartments help separate processes so they can happen in the right place. The compartment called the cytosol is the fluid part of the cell. It surrounds the other internal structures and helps support many cell processes. Inside the cell, membrane-bound organelles create distinct microenvironments. A microenvironment is a small internal space with conditions that fit a specific task. This separation...

The tree of life shows how organisms are related through evolution. Its root represents the common ancestor of all life on Earth. From that point, branches spread out like a tree. The tips of the branches represent living, or extant, species. Species that no longer exist, called extinct species, appear closer to the center of the tree. Today, these organisms are grouped into three domains: bacteria, archaea, and eukaryotes. Scientists still debate these divisions, so the tree of life keeps...

mutations

How Mutations Change DNA

Mutations are changes in DNA. They can alter the genetic code and affect how genes work. In high school biology, students often study mutations to understand how DNA changes can influence traits. The transcript focuses on two common mutation types: point mutations and frameshift mutations. A point mutation changes one nucleotide, which is one DNA building block. A frameshift mutation happens when nucleotides are added or removed and the reading frame shifts. These changes matter because they...

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

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,...

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

Explore the tree of life and the three domains of life: bacteria, archaea, and eukaryotes. Learn how scientists classify organisms and trace evolution.

How Life Is Classified Into Three Domains | 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.

Earth and Space Science

Earth’s Systems

HS-ESS2-6

Florida Department of Education

SC.912.L.14

SC.912.L.14.5

Texas Essential Knowledge and Skills

Biology

BIO.5

BIO.5.B

new-york-state-science-learning-standards

New York State Science Learning Standards

Earth and Space Sciences

HS-ESS2-7.

Georgia Standards of Excellence

9-12

SB4.a

DNA as a Genetic Template

Structure of a Gene

A gene is the fundamental unit of heredity. Every individual has two copies of each gene, one inherited from each parent. Although most people contain the ...

DNA Packaging

Organization of Genes

Chromosome Structure

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

The Nucleosome

DNA in a human cell is almost 2m long and it is packed inside a tiny nucleus that is only a few microns in diameter. The level of compaction of DNA inside ...

Chromatin Packaging

Each human somatic cell contains 6 billion base-pairs of DNA. Each base-pair is 0.34 nm long, which means that each diploid cell contains a staggering 2 ...

Karyotyping

Position-effect Variegation

In 1928, a German botanist Emil Heitz observed the moss nuclei with a DNA binding dye. He observed that while some chromatin regions decondense and spread ...

Histone Modification

The histone proteins have a flexible N-terminal tail extending out from the nucleosome. These histone tails are often subjected to post-translational ...

Spreading of Chromatin Modifications

The histone&#160;proteins in the nucleosomes are post-translationally modified (PTM) to increase or decrease access to DNA. The commonly observed PTMs are ...

Lampbrush Chromosomes

In 1882, Flemming observed lampbrush chromosomes (LBC) in salamander eggs. Later in 1892, R&#252;ckert observed LBCs in shark egg cells and coined the ...

Polytene Chromosomes

Polytene chromosomes are giant interphase chromosomes with several DNA strands placed side by side. They were discovered in the year 1881 by Balbiani in ...

Histone Variants at the Centromere

Histone variants are the histone proteins with structural and sequence variations. These variants may be regarded as &#8220;mutant&#8221; forms that ...

Inheritance of Chromatin Structures

Epigenetics is the study of inherited changes in a cell&#39;s phenotype without changing the DNA sequences. It provides a form of memory for the ...

Euchromatin

The extent of chromatin compaction can be studied by staining chromatin using specific DNA binding dyes. Under the microscope, the dense-compacted regions ...

Heterochromatin

chromatin-position-affects-gene-expression

Chromatin Position Affects Gene Expression

Chromatin is the massive complex of DNA and proteins packaged inside the nucleus. The complexity of chromatin folding and how it is packaged inside the ...

Genetics of Organisms

Mendelian Genetics
Evolution is caused by changes in the genetic composition of populations. In the field of population genetics, scientists model this ...

REF and WEF Fly Genetics
ExpandTo prepare for the experiment, be sure to obtain cultures of Drosophila melanogaster at least two weeks ahead of the ...

REF and WEF Fly Genetics
ExpandNOTE: At your station, you should have four vials of flies. They will be labeled as male or female. They will also be ...

Genetic Lingo

Overview

An organism is diploid if it inherits two variants, or alleles, of each gene, one from each parent. These two alleles constitute the genotype ...

Punnett Squares

Overview

A Punnett square displays the possible genotypes offspring can inherit from two parental genotypes. If a trait&#x2019;s inheritance pattern ...

Monohybrid Crosses

Overview

In the 1850s and 1860s, Gregor Mendel investigated inheritance by performing monohybrid crosses in pea plants. He crossed two plants that were ...

Dihybrid Crosses

Overview

To determine whether traits are inherited together or separately, Gregor Mendel crossed pea plants that differed in two traits. These parental ...

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 Segregation

When crossing pea plants, Mendel noticed that one of the parental traits would sometimes disappear in the first generation of offspring, called the F1 ...

Law of Independent Assortment

While Mendel&#x2019;s Law of Segregation states that the two alleles for one gene are separated into different gametes, a different question of how ...

Test Cross

Alleles are different forms of the same gene. Humans and other diploid organisms inherit two alleles of every gene, one from each parent.

An allele is ...

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

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 ...

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 ...

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 ...

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 ...

Multiple Allele Traits

The Concept of Multiple Allelism

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

X and Y Chromosomes

Among mammals, the gender of an organism is determined by the sex chromosomes. Humans have two sex chromosomes, X and Y. Every human diploid cell has 22 ...

Chromosomal Theory of Inheritance

In 1866, Gregor Mendel published the results of his pea plant breeding experiments, providing evidence for predictable patterns in the inheritance of ...

The Y Chromosome Determines Maleness

The Y chromosome is a sex chromosome&#160;found in several vertebrates and mammals, including humans. In addition to 22 pairs of autosomes, the human ...

Non-nuclear Inheritance

Most DNA resides in the nucleus of a cell. However, some organelles in the cell cytoplasm⁠&mdash;such as chloroplasts and mitochondria⁠&mdash;also ...

The Ratio of X Chromosome to Autosomes

In most organisms, sex is determined by the ratio of X and Y chromosomes. However, in some organisms, such as Drosophila and C.elegans, sex is determined ...

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 ...

X-linked Traits

In most mammalian species, females have two X sex chromosomes and males have an X and Y. As a result, mutations on the X chromosome in females may be ...

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 ...

Sex-linked Disorders

Like autosomes, sex chromosomes contain a variety of genes necessary for normal body function. When a mutation in one of these genes results in biological ...

Epistasis

In addition to multiple alleles at the same locus influencing traits, numerous genes or alleles at different locations may interact and influence ...

X-Inactivation

The human X chromosome contains over ten times the number of genes as in the Y chromosome. Since males have only one X chromosome, and females have two, ...

Polygenic Traits

When more than one gene is responsible for a given phenotype, the trait is considered polygenic. Human height is a polygenic trait. Studies have uncovered ...

Dosage Compensation

In animals, gender is determined by the number and type of sex chromosome. For example, human females have two X chromosomes, and males have one X and one ...

Pleiotropy

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

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.]

HS-LS3-1

Genome Size and the Evolution of New Genes

Gene Families

Gene Evolution - Fast or Slow?

Types of Genetic Transfer Between Organisms

What is Meiosis?

Meiosis I

Meiosis is the division of a diploid cell into haploid cells forming sperm and eggs in animals through differentiation. Meiosis I is the first stage of ...

Meiosis II

Meiosis II entails cell division and segregation of the sister chromatids, resulting in the production of four unique haploid gametes. The steps for ...

Meiosis vs. Mitosis

Cell division is necessary for growth and reproduction in organisms. Mitosis aids cell growth and development by dividing somatic cells. In contrast, ...

Crossing over

Nondisjunction

Replication in Eukaryotes

Overview

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

Proofreading

Synthesis of new DNA molecules starts when DNA polymerase links nucleotides together in a sequence that is complementary to the template DNA strand. DNA ...

Mismatch Repair

Overview

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

Nucleotide Excision Repair

Overview

Exposure to mutagens can damage DNA and result in bulky lesions that distort the double-helix structure or impede proper transcription. Damaged ...

Cancer Prevention

Several factors can increase the risk of cancer in an individual. About 50% of cancer cases can be prevented by adopting a healthy lifestyle, regular ...

cancers-originate-from-somatic-mutations-in-a-single-cell

Cancers Originate from Somatic Mutations in a Single Cell

Cancer arises from mutations in the critical genes that allow healthy cells to escape cell cycle regulation and acquire the ability to proliferate ...

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

comparing-copy-number-variations-and-snps

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 ...

Gene Conversion

Other than maintaining genome stability via DNA repair, homologous recombination plays an important role in diversifying the genome. In fact, the ...

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. [Clarification Statement: Emphasis is on using data to support arguments for the way variation occurs.] [Assessment Boundary: Assessment does not include the phases of meiosis or the biochemical mechanism of specific steps in the process.]

HS-LS3-2

How Life Is Classified Into Three Domains

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