Download The Nature of Life on Earth Define life? or Describe life

Define life?
or
Describe life?
The Nature of
Life on Earth
Life in the Universe Astrobiology
Dr. R. L. Hudson (Fall, 2015)
Characteristics of
Life on Earth
Chemistry
C H O N
Atoms, molecules, ions
Non-equilibrium
Isolated from
surroundings
Takes stuff in and
moves it out
Reproduction,
passes on traits
Evolves
Common Elements and Compounds
H
C
N
O
CH4
NH3
H2O
methane
ammonia
water
Cells
Energy
Environment
Chiral Molecules
Mirror
Twenty Amino Acids (AAs)
Proteins = Chains of Amino Acids
Twenty-Five Alanines
(20)25 = 340 000 000 000 000 000
000 000 000 000 000
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Big Question:
Double helix
Complimentary strands
How does biology
get it right?
A
Big Answer:
T
Chemistry!
G
DNA, the
Master
Molecule
C
DNA’s Protein Synthesis Method (In Brief!)
DNA Data
A few billion base pairs
in the DNA of a cell
DNA (our hero)
Thousands of base
pairs per human gene
Total DNA mass … about 0.5 grams
DNA in a human cell ~ 2 meters!
1013 cells … 10 billion miles!
See page 176.
The Genetic Code
Simplified version
1. RNA copies ATGC sequence
2. RNA attaches to other molecules,
which line up AAs (genetic code)
3. AAs link to give proteins!
DNA’s Reproductive Method (In Brief!)
2
DNA is common to
all terrestrial life.
Earth Life Shares a Common Chemistry
1. CHON + PS
DNA is
everywhere!
DNA is Common to
all Terrestrial Life
Characteristics
of
Life on Earth
2. Amino acids
3. Proteins (and enzymes)
4. DNA
Chemistry
Cells
Energy
Environment
Cells – Also Common!
Prokaryote
Eukaryote
Three Domains
of Life
3
Characteristics
of
Life on Earth
Life Needs Energy!
Chemistry
Cells
Energy
Environment
Plants Use Light – Photosynthesis!
6 CO2 + 6 H2O  C6H12O6 + 6 O2
C6H12O6 + 6 O2
Plants
Animals
ENERGY
Animals Use Plants
C6H12O6 + 6 O2  6 CO2 + 6 H2O
Some Astrobiology Lessons
Chemistry – CHON (and PS)
Molecule doing DNA’s work
6 CO2 + 6 H2O
6 CO2 + 6 H2O
Some Astrobiology Lessons
Chemistry –
CHON (and PS)
Molecule doing
DNA’s work
Dr. Julius Hibbert
Dr. Stephan Jay Gould
Cells – Primitive ones
Energy – Plant types first
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Characteristics
of
Life on Earth
Environments
Chemistry
Cells
Energy
Environment
Extreme Environments
Spirochaeta americana,
a thermophile
Extremophiles
Cryophiles:
5 F (-15 C) Cryptoendoliths (Antarctica)
news.nationalgeographic.com/news/2003/09/photogalleries/throughthelens/photo3.html
http://www.astrobio.net/news/
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Halophiles are salt-loving bacteria.
Tubeworms
Can grow to ~ 9 feet long
“Record holders can survive
30% salt, or 9 times
human blood saltiness.”
Depend on bacteria living inside them
“These bacteria convert the chemicals
that shoot out of the hydrothermal vents
into food for the worm.”
http://www.astrobio.net/news/
http://www.ocean.udel.edu/kiosk/riftia.html
Desert varnish
Methanobacterium thermoautotrophicum,
A reddish coating "of clay and iron
oxide precipitated by remarkable bacteria”
a methanogenic archaeon
www.desertusa.com/magdec97/varnish/dec_varnish.html
“Methane ice worms …ingest bacteria that
feed off of methane hydrate deposits
in deep, dark, cold ocean depths.”
www.science.psu.edu/iceworms/iceworms.html
www.micrbiol.sci.kun.nl/gallery.html
Deinococcus radiodurans
“… can withstand without loss of viability a dosage
that is 3,000 times greater than what would kill a human.”
science.nasa.gov/newhome/headlines/ast14dec99_1.htm
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Spirochaeta americana
Many Life-Supporting Environments
“... found in … an alkaline,
briny oxygen-limited lake
in a closed volcanic crater ...”
Green = living cells
Others = dead cells
Hot
Bright, Dry
Acidic
Cold
Dark, Wet
Basic
High Radiation Doses
www1.msfc.nasa.gov/NEWSROOM/NSSTC/news/photos/2003/photosN03-007.html
An Example
Sources of Material
Europa,
a moon
of
Jupiter
Most of the images used here are either original,
from our class’s textbook, or in the public
domain. Material not fitting into these
categories has been credited in cases where I
knew the sources. I will be glad to add any
credits missed. Obviously a few othe images
are copied from well-known television programs.
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