Post on 30-Jan-2016
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Water and LifeWater and Life
Radius of the earth:
Circumference of the earth:
Total water on earth:
Age of the earth:
Water’s appearance on the earth:
% readily available fresh water:
3 sources of earth’s water:
Setting the stage for the evolution of advanced forms of life
Water is an essential precursor to life.
Water and Life
The most abundant substance in living systems
%Human body = 65% Plants = 80%Fruits and Vegetables = 70-80%
70
New born baby ~ 77% Grown-up man ~ 65% Grown-up woman ~ 58% The elderly ~ 50%
Water and Life
Water is an ideal medium for biochemical reactions:
1. retains heat, moderates temperature2. excellent solvent3. transports nutrients, life compounds4. Participates in reactions
22% 73% 79% Heart 77% Lungs 80%Kidneys 80% Brain 85%
same salinity as the ocean
A loss of just 5 percent of the body's total water will cause the mouth to go dry, the surface of the skin to shrink, and may even cause hallucinations
A loss of more than 12 - 15 percent total body fluid would be fatal.
The longest anyone has ever survived without water is _____
15 percent of human water loss is through the act of respiration
20 percent is lost through perspiration
65 percent is lost by excretion
Average person has about 50 quarts of body water
Water and Life’s Beginnings
Commonality in all living things:
• Organisms consist of similar organic (carbon-rich) compounds.
• Proteins found in present-day organisms are fashioned from one set of 20 standard amino acids
proteins are essential to development, growth, and reproduction
DNA Amino Acids ProteinsCatalysisMetabolismgrowth
RNA
Catalysis
Human body is 18% carbon
Proteins
To make a protein, the combination of amino acids requires reaction with water.
Protein Synthesis
Water and Life
The Miller Experiment
Ocean
Atmosphere 14 of the 20 natural amino acids appear
Water is necessary for protein synthesis from AAs
Proteins are necessary for synthesis of DNA/RNA
DNA/RNA carry genetic information necessary for life
Water as a Precursor to Life
3.35 – 3.5 bya
~ 4.4 bya
It all starts with water
First Organisms
Anaerobic: live in oxygen – free environments
Autotrophic: produce complex organic compounds from simple inorganic molecules and an external source of energy.
Organic compounds: glucoseInorganic molecules: CO2 Energy source: light or chemical reactions (sulfide, iron)
Light: photoautotroph chemicals: chemoautotroph
Embedded in the lava are numerous tubular structuresleft behind by ancient microbes
Earliest Organisms
chemoautotrophic
~ 3.5 bya
tubes contain carbon that represents organic material left behind by the early organisms.
Cyanobacteria
Photosynthetic
3.0 – 3.5 bya
CO2 + H2O C6H12O6 + O2
light
Fix atmospheric carbondioxide into complex organic compounds.
(Simplified)- removed carbon dioxide - added oxygen to the atmosphere
bacterial fossils 3.5 bya
(Blue-green algae)
Stromatolites
Colonies of Cyanobacteria
the oldest macroscopic evidence of life on Earth, at least 2.5 billion years old
Produced billions of tons of oxygen
Calcium CarbonateCyanobacteria colonies
Dissolved Iron in oceans
CO2 + H2O C6H12O6 + O2
light
Banded Iron Formations
2 Fe II + 3O2 Fe2O3
Approximately 2.0 bya
In oceans
ferrous ferric
CO2 + H2O C6H12O6 + O2
light
Approximately 1.5 bya
2 Fe II + 3O2 Fe2O3
emergence of complex cellsand multi-cellular organisms
Oxygen in the Atmosphere/Oceans
Oceanic
coincides
~ 400 million years
Higher Oxygen Levels
Ozone Layer
Terrestrial Life
Carboniferous Period
About 350 million years ago
“the age of swamps and coal"
245 mya – 65 mya
Age of Reptiles
WarmWetProductive
Primates ~30 million years ago
Pre-humans ~5 million years ago
Homo sapiens ~200,000 years ago
Mammals ~65 million years ago
Subsequent Timeline
Liquid water 3.5 – 4.4 bya
Earliest organisms 3.5 bya
Cyanobacteria 3.0 – 3.5 bya
Stromolites 2.5 bya
Iron Formations 2.0 bya
Atmospheric O2 increase 1.5 bya
Complex/multicells 1.0 bya
Ozone Layer 400 mya
Carboniferous 350 mya
Reptiles 245 mya
Mammals 65 mya
Next: Water and the Fossil Record