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