The Nature of Define life? Life on Earth or Describe life?
Atoms, molecules, ions Non-equilibrium
Life in the Universe - Isolated from Takes stuff in and surroundings moves it out Astrobiology Reproduction, Dr. R. L. Hudson (Spring, 2018) Evolves passes on traits
Characteristics of Common Elements and Compounds Life on Earth H Chemistry CNO C H O N
Cells CH4 NH3 H2O Energy
Environment methane ammonia water
Chiral Molecules Twenty Amino Acids (AAs) Mirror Proteins = Chains of Amino Acids
Twenty-Five Alanines
(20)25 = 340 000 000 000 000 000 000 000 000 000 000
1 Big Question: Double helix Complimentary strands How does biology get it right? T A Big Answer: Chemistry!
G C DNA, the Master Molecule
DNA Data DNA’s Protein Synthesis Method (In Brief!) A few billion base pairs in the DNA of a cell DNA (our hero) Thousands of base pairs per human gene 1. RNA copies ATGC sequence Total DNA mass … about 0.5 grams 2. RNA attaches to other molecules, DNA in a human cell ~ 2 meters! which line up AAs (genetic code) 1013 cells … 10 billion miles! 3. AAs link to give proteins!
See page 180. Simplified version The Genetic Code DNA’s Reproductive Method (In Brief!) Marshall Nirenberg, NIH
2 DNA is common to DNA is DNA is Common to all terrestrial life. everywhere! all Terrestrial Life
Earth Life Shares a Common Chemistry Characteristics of 1. CHON + PS Life on Earth 2. Amino acids Chemistry 3. Proteins (and enzymes) 4. DNA Cells
Energy
Environment
Cells – Also Common! Prokaryote Eukaryote
Three Domains of Life
3 Characteristics of Life Needs Energy! Life on Earth
Chemistry
Cells
Energy
Environment
Plants Use Light – Photosynthesis!
C6H12O6 + 6 O2 6 CO2 + 6 H2O C6H12O6 + 6 O2
Plants Animals ENERGY
Animals Use Plants
6 CO2 + 6 H2O 6 CO2 + 6 H2O C6H12O6 + 6 O2 6 CO2 + 6 H2O
Some Astrobiology Lessons Some Astrobiology Lessons
Chemistry – Molecule doing Chemistry – CHON (and PS) CHON (and PS) DNA’s work Molecule doing DNA’s work
Cells – Primitive ones
Energy – Plant types first Dr. Julius Hibbert Dr. Stephan Jay Gould
4 Characteristics Environments of Life on Earth
Chemistry
Cells
Energy
Environment
Extreme Environments Extremophiles
Spirochaeta americana, Cryophiles: a thermophile 5 F (-15 C) Cryptoendoliths (Antarctica)
news.nationalgeographic.com/news/2003/09/photogalleries/throughthelens/photo3.html http://www.astrobio.net/news/
5 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
Methanobacterium thermoautotrophicum, “Methane ice worms …ingest bacteria that a methanogenic archaeon 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 Spirochaeta americana
“... found in … an alkaline, briny oxygen-limited lake in a closed volcanic crater ...”
Green = living cells Others = dead cells “… 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 www1.msfc.nasa.gov/NEWSROOM/NSSTC/news/photos/2003/photosN03-007.html
6 An Example Many Life-Supporting Environments Europa, a moon Hot Cold of Bright, Dry Dark, Wet Jupiter
Acidic Basic
High Radiation Doses
Sources of Material
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.
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