1 / 24

ASTR-3040: Astrobiology

ASTR-3040: Astrobiology. The Nature of Life on Earth Chapter 5. Day 11. Homework - 4. Due Tues. Feb. 22 Chapter 5: 4, 6, 14, 20, 25, 27, 33, 37, 42, 47, 48, 49, 51. Molecular Components. Carbohydrates – energy sources Sugars and starches Lipids – energy stores, barriers Fats

tashya-brady
Télécharger la présentation

ASTR-3040: Astrobiology

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. ASTR-3040: Astrobiology The Nature of Life on Earth Chapter 5 Day 11

  2. Homework - 4 • Due Tues. Feb. 22 • Chapter 5: • 4, 6, 14, 20, 25, 27, 33, 37, 42, 47, 48, 49, 51

  3. Molecular Components • Carbohydrates – energy sources • Sugars and starches • Lipids – energy stores, barriers • Fats • Nucleic Acids – DNA and RNA

  4. Molecular Components • Proteins – structure & chemistry • Structural materials • Enzymes – catalysts for reactions • Amino Acids (20 used in most life forms)‏ • Left-handed in biological entities.

  5. Major Groupings • Leeuwenhoek – 1674 – microscope • 5 Kingdoms • Plants • Animals • Protista • Monera • Fungi • Is there a biochemical classification?

  6. Microscopic Life • Plants and Animals are different • Cell walls (plants)‏ • Cell Nucleus • Prokaryotes • Eukaryotes All prokaryotes are single celled. They lack a cell nucleus. Eukaryotes – single or multi-celled.

  7. Domains of Life • Based on biochemistry and genetics: • Bacteria • Archaea • Eukarya Tree of life. Kingdom – Phylum – Class – Order – Family – Genus – Species

  8. The Tree of Life • Extremely valuable organizational tool. • 3 key ideas • 1. Domains based on biochemistry & genetics is fundamentally different from the older KPCOFGS based on structural & physiological differences. • 2. New and fundamentally different view of microbes - lipid structure of cell membranes. • 3. True diversity almost entirely in microbes.

  9. Metabolism: Chemistry of Life • Metabolic needs: • 1. Source of raw materials. • 2. Source of energy. • ATP: adenosine triphosphate • Used by every living cell for internal energy. • Outside energy needed only to produce ATP. • Carbon sources – form basic materials. • Energy sources – run the metabolism.

  10. Classification by Metabolism • To obtain carbon: • 1. Heterotrophs: Consume preexisting organic compounds (i.e. eating). • 2. Autotrophs: Direct uptake from the environment (self-feeding, plants)‏

  11. Classification by Metabolism • To obtain energy: • 1. Photosynthesis: sunlight • 2. chemosynthesis: chemical energy • Ingested food • Inorganic reactions

  12. 4 Metabolic Classifications • Based on energy and carbon acquisition. • 1. Photoautotrophs • 2. Chemoautotrophs • 3. Photoheterotrophs • 4. Chemoheterotrophs

  13. Liquid Water on Earth • All living cells on Earth depend on liquid water because metabolism requires: • 1. Organic chemicals are readily available for reactions. • 2. A means of transporting chemicals to and within cells; waste products away. • 3. Water plays a role in many of the reactions.

  14. DNA and Heredity • 3 key features of life on Earth • 1. structural units – cells • 2. metabolic processes – energy production • 3. owner's manual – data storage for how a cell is constructed, how it works, and how to build another one, and pass it on to the next generation - heredity.

  15. DNA Structure • Double helix • DNA bases – 4 • Adenine • Guanine • Thymine • Cytosine • Pair as AT & CG

  16. Replication • Unzip & each strand acts as a template. • Use RNA in the rebuild process.

  17. Genome • Humans have ~3 X 10^9 bases • 46 chromosomes (23 pairs)‏ • Sequences for individual instructions are called genes. • Most of DNA is “noncoding” (junk 95%)‏ • Complete sequence – genome. Some bacteria – 10^5 bases, few 10^2 genes Humans – 20,000 – 25,000 genes Rice – 37,000 genes (smaller DNA sequence)‏

  18. Genetic Code • Words consist of 3 DNA bases. • Sequence has a start and stop word. • Used to build proteins. • Redundancy (64 codes, 20 amino acids)‏ • Most amino acids are coded with the first 2 base letters only (16). Does this give a clue to evolution of complex organisms? • Nearly all living organisms have mostly similar genetic code.

  19. RNA • Uses ACG & Uracil • mRNA – transcription (carries the instr.)‏ • tRNA – transfer (gathers the AAs)‏ • rRNA – backbone of building structure. • Mutations - <1:10^9, but can have dramatic consequences. • Provide the basis for evolution. • Genetic Engineering. • RNA was probable precursor.

  20. Extreme Life - Extremophiles • Thermophiles – heat lovers • Hyperthermophiles • Black smokers (350˚C)‏ • Hot springs

  21. Extreme Life - Extremophiles • Psychrophiles – cold lovers • Antarctica ice pack (-20˚C)‏ • Also very dry Radiation hardened

  22. Extreme Life - Extremophiles • Endoliths – within rocks • Up to several km below ground • Endospores (resting) – found on moon • Could these survive interplanetary journeys?

More Related