Name: how early cells got their start
Uploaded: 2026-03-12T13:57:39.000Z
Duration: 1 min 24 s
Channel: JoVE

K12 Standards

Alabama Course of Study Science

9-12

Environmental Science

Earth's Systems

9-12.EVS.3.4

Origin of Cellular Life

Una de las varias hipótesis sugiere que las formas de vida más antiguas probablemente se originaron en fuentes hidrotermales en el fondo oceánico.Las fuentes hidrotermales proporcionaban calor, gradientes químicos y compuestos inorgánicos, como hidrógeno y sulfuro de hidrógeno. Este entorno podría haber facilitado la síntesis abiótica de moléculas orgánicas, incluyendo aminoácidos, lípidos y nucleótidos.Los poros minerales dentro de las estructuras de las fuentes hidrotermales podrían haber servido como los primeros compartimentos biológicos, concentrando estas moléculas y reuniéndolas para reacciones químicas.Algunos modelos sugieren que las protocélulas surgieron cuando se formaron las membranas lipídicas, reemplazando finalmente a los compartimentos de base mineral.Estas células probablemente contenían ARN autorreplicante, capaz de almacenar información genética y catalizar la síntesis de proteínas.A medida que surgieron las proteínas, sus interacciones con el ARN probablemente impulsaron la transición al ADN, un material genético más estable.Metabólicamente, las primeras células probablemente eran quimiolitotróficas, que usaban hidrógeno como donante de electrones y azufre o dióxido de carbono como aceptores de electrones para sintetizar compuestos orgánicos.

origen de la vida celular

El origen de la vida en la Tierra es un evento complejo y enigmático arraigado en procesos bioquímicos antiguos y condiciones geológicas. La evidencia experimental apoya la hipótesis de que la vida comenzó con la formación espontánea de moléculas orgánicas como nucleótidos de ARN, aminoácidos y lípidos bajo condiciones terrestres tempranas. Factores como la actividad volcánica, la intensa radiación UV y una atmósfera reductora sin oxígeno libre probablemente facilitaron estas reacciones. Las fuentes hidrotermales en el fondo oceánico se consideran un lugar probable para las primeras formas de vida, ya que podrían suministrar gases reducidos como hidrógeno (H₂) y sulfuro de hidrógeno (H₂S), facilitando la química prebiótica. Los poros minerales proporcionan espacios confinados que concentran los reactivos, a diferencia del océano abierto donde las moléculas se diluirían mucho. Además, las superficies minerales —a menudo ricas en hierro y azufre— pueden actuar como catalizadores primitivos. Estas superficies pueden haber ayudado a acelerar las reacciones químicas al poner las moléculas en contacto cercano y reducir la energía necesaria para que las reacciones ocurran.Se cree que el ARN desempeñó un papel central en la vida temprana debido a su capacidad para almacenar información genética y catalizar reacciones bioquímicas. Las ribozimas demuestran que el ARN puede desempeñar funciones similares a las enzimáticas, ofreciendo una etapa intermedia plausible antes de la evolución de enzimas basadas en proteínas. La eventual aparición del ADN, ARN y proteínas sentó las bases para la arquitectura molecular tripartita compartida por todos los organismos modernos. Se estima que el último ancestro común universal (LUCA) vivió hace aproximadamente entre 3,8 y 3,7 mil millones de años, marcando la divergencia entre bacterias y arqueas, aunque el momento exacto sigue siendo incierto.La vida celular temprana se diversificó metabólicamente en el entorno anóxico de la Tierra. Los autótrofos primitivos utilizaban CO₂ como fuente de carbono, a menudo confiando en H₂ como donante de energía. La evolución de la fijación de nitrógeno amplió las posibilidades metabólicas, mientras que las vías energéticas basadas en azufre probablemente proporcionaron reacciones esforzónicas adicionales. La quimiolotofofía impulsada por hidrógeno permitió la síntesis de moléculas orgánicas a partir de CO₂, sosteniendo ecosistemas cada vez más complejos. Con el tiempo, las innovaciones microbianas —incluida la aparición de la fotosíntesis oxigénica— transformaron la atmósfera terrestre, permitiendo finalmente el auge de la vida aeróbica.

Origen de la vida celular

The origin of life on Earth is a complex and enigmatic event rooted in ancient biochemical processes and geological conditions. Experimental evidence ...

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Education

Educación

JoVE Core

Microbiology

Microbiología

Unit

Unidad

Microbial Evolution

Evolución microbiana

KEY TERMS AND CONCEPTS

TÉRMINOS Y CONCEPTOS CLAVE

how early cells got their start

Early cellular life began under the harsh conditions of early Earth, where simple chemicals could form more complex organic molecules. Experimental evidence supports the idea that RNA nucleotides, amino acids, and lipids could arise spontaneously in this environment. Volcanic activity, strong UV radiation, and an atmosphere with little or no free oxygen likely helped drive these reactions.

Hydrothermal vents on the ocean floor are considered one likely setting for the first life forms. These vents could supply reduced gases such as hydrogen and hydrogen sulfide, which support prebiotic chemistry, or chemistry that happens before life exists. Mineral pores would have trapped molecules in small spaces, so reactants were less diluted than they would be in the open ocean.

Mineral surfaces may also have helped early reactions. Many of these surfaces are rich in iron and sulfur, and they can act as primitive catalysts. A catalyst speeds up a reaction by lowering the energy needed and by bringing molecules close together.

RNA likely played a major role in early life because it can store genetic information and also help carry out chemical reactions. RNA molecules that act like enzymes are called ribozymes, and they show how RNA could have worked before protein enzymes evolved. Over time, DNA, RNA, and proteins formed the basic molecular system shared by modern organisms.

Scientists estimate that the last universal common ancestor, or LUCA, lived about 3.8 to 3.7 billion years ago. This was the point at which Bacteria and Archaea began to diverge, although the exact timing is still uncertain. Early cells then diversified in Earth’s oxygen-free environment.

Primitive autotrophs used carbon dioxide as a carbon source and often depended on hydrogen as an energy donor. Later, nitrogen fixation expanded the kinds of metabolism that were possible. Sulfur-based energy pathways also likely provided useful energy, and hydrogen-driven chemolithotrophy helped cells make organic molecules from carbon dioxide. Over time, microbial innovations, including oxygenic photosynthesis, changed Earth’s atmosphere and made aerobic life possible.

How Early Cells Got Their Start

origin of cellular life

Early cellular life began under the harsh conditions of early Earth, where simple chemicals could form more complex organic molecules. Experimental evidence supports the idea that RNA nucleotides, amino acids, and lipids could arise spontaneously in this environment. Volcanic activity, strong UV radiation, and an atmosphere with little or no free oxygen likely helped drive these reactions. Hydrothermal vents on the ocean floor are considered one likely setting for the first life forms. These...

origin of photosynthesis

How Photosynthesis Changed Earth

Photosynthesis changed Earth’s atmosphere and made complex life possible. It began about 3.4 to 3.8 billion years ago, when the first photosynthetic organisms used light energy to build organic compounds. These early organisms were anoxygenic phototrophs, which means they made food from light but did not release oxygen. Early photosynthesis used hydrogen sulfide (H2S) or ferrous iron (Fe2+) as electron donors instead of water. Because of that, it did not produce molecular oxygen (O2) as a...

evolutionary processes in microbes

How Microbes Gain New Traits

Microbes gain new traits through fast genetic change. Their short generation times help evolution happen quickly. Mutation, horizontal gene transfer, recombination, and genetic drift all contribute to this process. Together, these mechanisms help microbial populations adjust to changing environments. Horizontal gene transfer, or HGT, moves genes between different species. It happens in three main ways: conjugation, transformation, and transduction. Conjugation requires direct cell-to-cell...

evolution of new traits in microbes

Microbial Adaptation in Changing Environments

Microbial adaptation in changing environments can happen very quickly. Microorganisms often evolve fast because they have large population sizes and short generation times. In the lab, these changes can sometimes be measured within days. Natural selection acts on standing genetic variation, which is the genetic diversity already present in a population. When conditions change, helpful traits can be kept and increased because they improve fitness. This lets microbes respond to new pressures...

evolution of microbial genome

Microbial Core and Pan-Genome Changes

Microbial genomes change through gene gain and gene loss. These changes help microbes adapt to new environments and to other organisms they live with. In many species, genome evolution is fast and ongoing. A key idea is the difference between the core genome and the pan-genome. The core genome is the set of genes shared by all sampled strains of a species. These genes support basic cell functions. For example, Salmonella enterica has about 2,800 core genes, although the exact number can change...

microbial phylogeny

Reading Microbial Family Trees

Reading microbial family trees helps scientists study how microorganisms are related. These trees are important in microbial ecology and taxonomy. They use molecular sequences such as DNA, RNA, or proteins to compare bacteria and archaea and trace genetic changes over time. A phylogenetic tree has tips, branches, and nodes. The tips are the species that are sampled or still alive. The branches show evolutionary paths, and branch length reflects the number of genetic changes between nodes.

phylogenetic species concept in microbiology

phylogenetic-species-concept-in-microbiology

How DNA Defines Microbial Species

The phylogenetic species concept helps define microbial species by looking at DNA and evolutionary relatedness. It focuses on shared ancestry and genetic traits that can be diagnosed in different organisms. This approach is especially useful in microbiology, where other species concepts often do not work well. Traditional morphological and biological species concepts rely on body form or reproduction. Those methods can fall short for microbes because many reproduce asexually, show little...

key terms and concepts

Explore how early cells may have formed on Earth, from RNA and hydrothermal vents to LUCA, early metabolism, and the rise of oxygenic photosynthesis.

How Early Cells Got Their Start | JoVE K12

JoVE Core Microbiology provides an engaging introduction to the microbial world and its influence on health, industry, and the environment. This comprehensive collection covers key concepts such as microbial structure, metabolism, genetics, and ecology. It introduces essential laboratory techniques and microscopy methods through visually engaging animations. Corresponding scientist-in-action videos bridge classroom concepts with real-world research and applications.

microbiology

Origin of Photosynthesis

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Soil Microbial Ecology

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Microbial Corrosion

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Analysis of Earthworm Populations in Soil

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What is an Ecosystem?

Overview

An ecosystem is the interaction between all abiotic and biotic factors in an environment and can be classified as terrestrial or aquatic. ...

4. Engage in an evidence-based argument to explain how Earth's systems affect the biosphere and the biosphere affects Earth's systems over various amounts of time. Examples: Use data to make a claim that microbial life increases the formation of soil or that corals create reefs and argue that these processes can alter patterns of erosion and deposition along coastlines. Clarification: This discussion should consider Earth's geological history.

Ecological Disturbance

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Igneous Volcanic Rock

Source: Laboratory of Alan Lester - University of Colorado Boulder
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Applications of GIS: Disaster Management and Emergency Response

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5. Obtain, evaluate, and communicate information regarding how short-term and long-term natural cyclic fluctuations cause ecosystem change. Examples: Explain how the eruption of volcanoes alters global temperatures or how the El Niño-Southern Oscillation shifts weather patterns. Share information regarding how forest fires can cause deforestation which increases water runoff and soil erosion. Describe how hurricanes destroy dunes and increase coastal flooding.

9-12.EVS.3.5

How Early Cells Got Their Start

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