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ASTR/GEOL-2040: Search for life in the Universe, Lecture 4

ASTR/GEOL-2040: Search for life in the Universe, Lecture 4. Ad69 6. Pages 6-10 in RGS Page 169 of BS. Axel Brandenburg (Office hours: Mondays 2:30 – 3:30 in X590 and Wednesdays 11-12 in D230). Cells are made of lipids. carboxyl group. hydrophylic.  amphobic. hydrophobic.

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ASTR/GEOL-2040: Search for life in the Universe, Lecture 4

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  1. ASTR/GEOL-2040: Search for life in the Universe, Lecture 4 Ad69 6 Pages 6-10 in RGS Page 169 of BS Axel Brandenburg (Office hours: Mondays 2:30 – 3:30 in X590 and Wednesdays 11-12 in D230)

  2. Cells are made of lipids carboxyl group hydrophylic  amphobic hydrophobic

  3. Common carbon compounds • carbohydrates • hydrocarbons

  4. Sugars are • Hydrocarbons • Carbohydrates • Hydroxyls • Carboxyls

  5. Sugars are • Hydrocarbons • Carbohydrates • Hydroxyls • Carboxyls

  6. Common carbon compounds • Hydrocarbons: made up entirely of hydrogen & carbon CH3-CH2-CH2-CH2-CH2-CH3 • Carbohydrates: made up of hydrogen, carbon, & oxygen Cm(H2O)n H-C-OH H-C-OH H-C-OH

  7. Glucose • Glucose=hexose=monosaccharide = C6H12O6 chemists drop C & H

  8. Another important sugar • Ribose = pentose = C5H10O5 • deoxyribose=C5H10O4 again: drop C & H …note 3-D perspective

  9. Why are sugars useful? • ...... • ........... • ................  think of carbohydrates more generally

  10. Why are carbohydrates useful? • Energy storage • Structural support • Food source for others

  11. Two more building blocks • Proteins • RNA & DNA: nuclei acids https://en.wikipedia.org/wiki/Central_dogma_of_molecular_biology

  12. What are proteins? • Proteios = primary • Berzelius (1838) C400H620N100O120P1S1 • Are the most complex macromolecules in living systems • Polymers of amino acids • ”peptides” are shorter polymers

  13. What are amino acids? • amino: -NH2 • acid: -COOH • and a C • and an H • and possibly another H NH2 H-C-H COOH

  14. Polymerization  polycondensation NH2 NH2 CH2 CH2 carboxyl group COOH CO “peptide bond” NH NH2 amino group CH2 CH2 COOH COOH glycine dipeptide

  15. Other amino acids • if R=CH3: alanine • valine, proline, sarcosine, ...

  16. Recognize 3 of the 4 endings? • COOH carboxyl group • OH hydroxyl group • CH3 methyl group • NH2 amino group (=amine group)

  17. Why are proteins important? • Structural support (e.g., finger nails) • Act as catalysts (=enzymes) • Facilitates/accelerates reactions • Not used up or involved in reaction • Can be reused many times! • Their exact role depends on sequence

  18. So many different ones • Only 20 amino acids in proteins • Although 70 have been identified • 2 (+) of them used in rare cases microbes • Folding • Depends on amino acid sequence • Determines how they work.

  19. Finally: nucleic acids

  20. Inventory • Polymers of nucleotides • Backbone • DNA (deoxyribonucleic acid) • or RNA (ribonucleic acid) • Pentose sugar (5 carbons) • Phosphate group • Nitrogen-containing base • four different ones • Form a spiral

  21. Inventory • Backbone • deoxyribonucleic acid, ribonucleic acid • Pentose sugar (5 carbons) • Phosphate group • Nitrogen-containing base

  22. Different bases • Two groups of bases: • pyrimidines T,C • purines A,G • These two groups pair in specific ways • T-A and A-T • C-G and G-C

  23. In which ways could life elsewhere be different? • Different backbones • Different base pairs

  24. An enzyme consists of a chain of • Carbohydrates • Amino acids • nucleotides

  25. Two more bases synthesized in 2014

  26. Think about other worlds • Large impacts can blast rocks into space • Life (spores) might survive in rocks • Suppose life on Mars is found with • Different sets of amino acids • Right-handed versions of amino acids • Does this support/contradict hypothesis that life migrated from Mars?

  27. What we talked about • The 4 different building blocks • Lipids, carbohydrates, proteins, nucleic acids • Their usefulness • Next time • How they propagrate genetic information • Genetic code • Biomarkers, biosignatures • pp. 11-17 of RGS

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