ERTH 5 (Jan 21st)

Typed

Earth up to this point

1. Sun Ignites]

2. Planetesimals collide

3. Earth forms

4. Earths core forms

5. Moon forming impact

6. Earth is fully differentiated

7. Late heavy bombardment

8. The Archean

But when did life form??

What is life

We know geochemistry turned to biochemistry, but when??

Definition of life?? :

• Program (organized DNA)

• Improvise (Mutation)

• Compartmentalize (membranes organs)

• Energy

• Regeneration

• Adaptability

• Seclusion

NASA’s definitions

Life is a self-sustaining chemical system capable of darwinian Evolution

Life must be made of organic molecules

• These are just two possible definition of life

• This does not take into account' ‘other forms’ which we are confronted within Sci-Fi

Primer What is lfe some key terminology, biology’s central dogma

• DNA: Stores information, and serves as the blueprint for the development and functioning of living organisms.

  • DNA cannot make proteins

• RNA Polymerase: An enzyme that synthesizes RNA from a DNA template, playing a crucial role in the transcription process.

• RNA: A molecule that acts as a messenger between DNA and ribosomes, carrying the genetic information needed for protein synthesis.

• Ribosomes: Cellular structures where proteins are synthesized, translating the information carried by RNA into functional proteins.

What is life made of?

C106 : N16 : P1

This is the ration of chemical make up for marine animals

Origin of life

Organic Soup

• A closed system

• organ compounds

• Energy

• Heat

This was tested over a 50 year period and yielded no results

Hydro Thermal Vents

• Offer sa steady source of energy (heat) and ingredients to drive metabolism

• Can be stable for long periods of time

• Would have been a critical habitat for early life forms, providing the necessary conditions for biological processes to occur in the absence of sunlight.

• The Wood-Ljungdahl or Acetyl CoA pathway

• This just needs hydrogen CO2

• Also proton gradients are already present at the vents

• Chemical Gradients house potential energy much like a dam holding naturualry back water. Hydrothermal Vents naturally produce these

• Alternatively…

  • Imaging taking all of these reaction and processes that make life work

  • Now strip away as much as we can and this thing still be considered life

  • This is preformed to determine is this yields life “core“

Other Plants

Did lifes ingreatends exist elsewhere in the solar system and was those materials then transferred to earth via meteoroid

We will never know this

Soda Lakes

• A lake that is alkaline IE pH form 9-12

• Such lakes can be rich in things essential for life like

• Asteroids impacts would also produce HCN in th eatmosphere

• Reactions with iron could have locked in substantial courses of HCN over millions of years

• Evaporations would concentrate theses molecules promoting synthesis of organic molecules essential for life

• Life would be constantly generating in different spaces

Tools to look for life

Biomarkers:

Most stubborn chemicals that last the longest and take a very long time to decay

• Cholesterolis a crucial biomarker that can indicate the presence of life, as it is a fundamental component of cell membranes in many organisms.

• However, data quality is key. it is critical to control for post-depositional introduction

• We also need to know for what to look for

Biosignatures:

• Life leaves a trial of clues: there would be no oxygen in the atmosphere without oxygenic photosynthesis

• Metabolisms leave specific signatures in the sedimentary record

Fossils

• Fossils are a great way to reconstruct the life on earth

• While we can gain lots of info form animal skeletons and teeth and scales microbes also provide crucial insights into ancient environments and biological processes, as their metabolic byproducts can reveal information about past climates and ecosystems. These microbial signatures can help us understand the conditions under which ancient organisms thrived, including nutrient availability and temperature fluctuations.

KAi

Geologic Time and Fossils

• The continental crust is felsic and rich in feldspars, while the oceanic crust is basic.

• Understanding geologic time is essential. The geologic time scale was not exclusively created based on biozones but utilized absolute ages as well. The reliance solely on the presence or absence of fossils in determining the geological era is considered false.

The Archaean Earth and Origins of Life

• The focus of discussion is on the Archaean Earth and the origins of life.

• Simple rocks are not considered alive. While fire can reproduce and produce energy, it does not classify as alive. Minerals and crystals, although exhibiting growth patterns, also do not fit the definition of life.

• A significant misconception is the placement of mammals and their representation of life on Earth. It is necessary to understand that most living biological mass comprises bacteria and smaller organisms, despite their size.

Biological Mass Distribution

• Life on Earth consists primarily of land plants, which account for the largest biomass component. Bacteria also represent a substantial biomass component, outweighing most animals, including insects. This points to a misunderstanding of the organisms that dominate life.

• The scale of living cells is incredible, with estimates of roughly 10^30 cells existing today. This astronomical number offers insight into the sheer diversity of microbial life.

• Over time, it is estimated that approximately 10^40 cells have existed, showcasing an extensive evolutionary process stemming from single-celled organisms.

Definition and Characteristics of Life

• Various definitions exist for what constitutes life. A NASA-defined life form is a self-sustaining chemical system capable of undergoing evolution.

• Essential biological components include proteins, which perform vital functions; DNA, which stores genetic information; and RNA, which aids in the production of proteins.

• Mutations can occur during DNA replication, with an estimated rate in bacteria being 1 error per 10,000 replications.

• Some mutations are beneficial, some are harmful, and many are neutral, contributing to the process of evolution.

Hypotheses of Life Origins

• The discussion on potential origins of life suggests several places, including solar lakes and thermal vents, as candidates for where life may have started.

• The Miller-Urey experiment can synthesize organic compounds in controlled conditions mimicking early Earth.

• The surrounding geological context—such as hydrothermal vents—may have provided conditions ideal for the development of the first living organisms.

The Role of Hydrothermal Vents

• Hydrothermal vents present environments rich in chemical energy. The presence of unique organisms, such as tube worms, around these vents illustrates the environmental diversity where life can thrive.

• Two types of vents are notable: black smokers (hotter and richer in minerals) and white smokers (cooler with a different chemical composition). Both support diverse ecosystems despite extreme conditions.

Metabolism and Energy Conversion

• Metabolic pathways, such as the acetyl CoA pathway, are essential for understanding how early organisms may have processed energy.

• Concepts of potential energy in ecosystems can be analogous to hydroelectric power, where energy is harnessed from the flow of water, mirroring how early life forms might have utilized environmental resources.

Tools for Studying Ancient Life

• Several methodologies exist to study ancient life, including molecular clocks, biomarkers, biosignatures, and fossils.

  • Molecular Clocks help determine the timing of evolutionary divergences based on mutation rates in DNA sequences.

  • Biomarkers are organic molecules indicative of past life, while biosignatures provide evidence of life’s influence on the environment.

  • Fossils serve as direct evidence of past organisms but require careful interpretation regarding their origin.

Challenges and Limitations in Studying Origins of Life

• It is crucial to recognize the challenges in accurately representing the origins of life, as observational data can sometimes be misleading.

• Conditions on other planets, such as Venus or Mars, require extensive study to understand the likelihood of life existing beyond Earth.

• Future missions to Mars may explore how these conditions relate to potential bottlenecks in life's development on Earth and other planets.

Conclusion

• Our exploration of the origins of life not only involves geological and biological perspectives but intertwines the understanding of evolutionary processes over billions of years. The tools and definitions created guide researchers in their ongoing quest to unveil the history of life.