THE ORIGIN AND EVOLUTION OF MICROBIAL LIFE THE

THE ORIGIN AND EVOLUTION OF MICROBIAL LIFE

THE ORIGIN AND EVOLUTION OF MICROBIAL LIFE • HOW DID LIFE ORIGINATE? – SPONTANEOUS GENERATION • LIFE ARISING FROM NON-LIVING MATTER • LONG BELIEVED AS THE ACCEPTED EXPLANATION OF ORIGINATION OF LIFE • EXPERIMENTS EVENTUALLY SHOWED IT TO BE IMPOSSIBLE – ORIGINATION OF LIFE HAD TO BE A STEP-WISE PROCESS

THE ORIGIN AND EVOLUTION OF MICROBIAL LIFE • MILLER AND UREY’S EXPERIMENT – ATTEMPTED TO EXPLAIN/SHOW EARLY EARTH COULD HAVE GIVEN RISE TO ORGANIC COMPOUNDS

THE ORIGIN AND EVOLUTION OF MICROBIAL LIFE • THE FIRST POLYMERS FORMED ON HOT ROCKS OR CLAY – EXPERIMENTS HAVE SHOWN HEAT ENERGY ON HOT SURFACES PROVIDES SUFFICIENT ACTIVATION ENERGY FOR DEHYDRATION SYNTHESIS REACTIONS

THE ORIGIN AND EVOLUTION OF MICROBIAL LIFE • THE FIRST GENETIC MATERIAL WAS PROBABLY RNA – WHY? – RIBOZYMES • RNA THAT ACTED AS ENZYMES

THE ORIGIN AND EVOLUTION OF MICROBIAL LIFE • MOLECULAR COOPERATIVES ENCLOSED BY MEMBRANES PROBABLY PRECEDED THE FIRST REAL CELLS – EXPERIMENTS HAVE SHOWN THAT IN AQUEOUS ENVIRONMENTS, CERTAIN KINDS OF MOLECULES, INCLUDING LIPIDS AND POLYPEPTIDES, CAN SELFASSEMBLE INTO MICROSCOPIC SPHERES FILLED WITH FLUID

THE ORIGIN AND EVOLUTION OF MICROBIAL LIFE • PROKARYOTES WERE PROBABLY THE FIRST FORMS OF LIFE BECAUSE… – SIMPLEST FORM OF LIFE (UNICELLULAR PROKARYOTE) – HAVE INHABITED EARTH FOR BILLIONS OF YEARS – IMMENSE NUMBER OF PROKARYOTES EXIST

THE ORIGIN AND EVOLUTION OF MICROBIAL LIFE • TWO MAIN FORMS OF PROKARYOTES – ARCHAEA VS. BACTERIA (EUBACTERIA) – EXTREMELY DIFFERENT FORMS OF BACTERIA – GENETIC DATA SUPPORTS 3 DOMAIN SYSTEM – BACTERIAL CELL WALLS CONTAIN PEPTIDOGLYCAN; NOT FOUND IN ARCHAEA – BACTERIAS COME IN A VARIETY OF SHAPES/STRUCTURES

THE ORIGIN AND EVOLUTION OF MICROBIAL LIFE • BACTERIAS

THE ORIGIN AND EVOLUTION OF MICROBIAL LIFE • PROKARYOTES OBTAIN NOURISHMENT IN A VARIETY OF WAYS

THE ORIGIN AND EVOLUTION OF MICROBIAL LIFE • PROKARYOTIC NOURISHMENT – “HETEROTROPH HYPOTHESIS” VS CHEMOAUTOTROPHIC HYPOTHESIS

THE ORIGIN AND EVOLUTION OF MICROBIAL LIFE • ARCHAEA CAME FIRST BECAUSE – THRIVE IN EXTREME ENVIRONMENTS AND THE OCEAN • EXTREME HALOPHILES SALT LOVERS • EXTREME THERMOPHILES HEAT LOVERS • METHANOGENS LIVE IN ANAEROBIC ENVIRONMENTS AND GIVE OFF METHANE AS A WASTE PRODUCT – JUST BECAUSE THEY CAME FIRST, DOESN’T MEAN THEY ARE SO OLD THEY ARE EXTINCT!! (ANCIENT DOES NOT EQUAL EXTINCT)

THE ORIGIN AND EVOLUTION OF MICROBIAL LIFE • DIVERSE STRUCTURAL FEATURES HELP PROKARYOTES THRIVE ALMOST ANYWHERE – PROKARYOTIC FLAGELLUM

THE ORIGIN AND EVOLUTION OF MICROBIAL LIFE • DIVERSE STRUCTURAL FEATURES HELP PROKARYOTES THRIVE ALMOST EVERYWHERE – PILI TINY APPENDAGES THAT HELP BACTERIA ATTACH TO EACH OTHER AND SURFACES – ENDOSPORES SPECIALIZED “INNER CELL” THAT CAN SURVIVE HARSH CONDITIONS, MAY REMAIN DORMANT FOR CENTURIES

THE ORIGIN AND EVOLUTION OF MICROBIAL LIFE • CYANOBACTERIA (A. K. A. BLUE-GREEN ALGAE) – SPECIFIC TYPE OF BACTERIAL CELL THAT CAN PERFORM PHOTOSYNTHESIS

THE ORIGIN AND EVOLUTION OF MICROBIAL LIFE • SOME BACTERIA CAUSE DISEASE – PATHOGENS DISEASE-CAUSING AGENTS – EXOTOXINS TOXIC PROTEINS SECRETED BY BACTERIAL CELLS – ENDOTOXINS COMPOUNDS OF THE CELL WALLS OF CERTAIN BACTERIA • SANITATION, ANTIBIOTICS, EDUCATION ARE WAYS TO DEFEND AGAINST BACTERIAL DISEASE

THE ORIGIN AND EVOLUTION OF MICROBIAL LIFE • DISEASE CAUSING BACTERIA

THE ORIGIN AND EVOLUTION OF MICROBIAL LIFE • BACTERIA CAN BE USED AS BIOLOGICAL WEAPONS • **PATHOGENIC PROKARYOTES ARE IN THE MINORITY, MOST PROKARYOTES ARE VITAL TO OUR WELL BEING – EXAMPLES: • NITRIFYING BACTERIA, DECOMPOSERS, ETC…

THE ORIGIN AND EVOLUTION OF MICROBIAL LIFE • THE EUKARYOTIC CELL PROBABLY ORIGINATED AS A COMMUNITY OF PROKARYOTES – MEMBRANE INFOLDING THE ORGANELLES (NOT MITOCHONDRIA AND CHLOROPLAST) ARISE FROM THE INWARD FOLDS OF THE PLASMA MEMBRANE OF A PROKARYOTIC CELL

THE ORIGIN AND EVOLUTION OF MICROBIAL LIFE • THE EUKARYOTIC CELL PROBABLY ORIGINATED AS A COMMUNITY OF PROKARYOTES – ENDOSYMBIOSIS ONE SPECIES LIVING WITHIN ANOTHER – EXAMPLES? ?

THE ORIGIN AND EVOLUTION OF MICROBIAL LIFE • PROTISTS – A DIVERSE GROUP OF MOSTLY UNICELLULAR EUKARYOTES; SOME PROTISTS ARE PHOTOSYNTHETIC, OTHERS ARE HETEROTROPHIC

THE ORIGIN AND EVOLUTION OF MICROBIAL LIFE

THE ORIGIN AND EVOLUTION OF MICROBIAL LIFE TWO GENERIC TYPES OF PROTISTS • ANIMAL-LIKE PROTISTS • A. K. A. PROTOZOA • PROTISTS THAT LIVE PRIMARILY BY INGESTING FOOD, A HETEROTROPHIC MODE OF NUTRITION THAT IS “ANIMAL-LIKE” • PLANT-LIKE PROTISTS • A. K. A. ALGAE • PROTISTS THAT LIVE BY SYNTHESIZING FOOD FROM CARBON DIOXIDE AND WATER, AN AUTOTROPHIC MODE OF NUTRITION THAT IS “PLANT-LIKE”

THE ORIGIN AND EVOLUTION OF MICROBIAL LIFE • GROUPS OF PROTISTS – FLAGELLATES – PSEUDOPODIA – CILIATES

THE ORIGIN AND EVOLUTION OF MICROBIAL LIFE • PHOTOSYNTHETIC PROTISTS ARE CALLED ALGAE – ALGAE DEF? ? – DINOFLAGELLATES – DIATOMS – GREEN ALGAE • PROBABLY MOST INTERESTING EVOLUTIONARILY, BECAUSE IT IS PROBABLY THE ANCESTOR OF LAND PLANTS

THE ORIGIN AND EVOLUTION OF MICROBIAL LIFE • SEAWEEDS ARE MULTICELLULAR MARINE ALGAE – THREE TYPES OF SEAWEED • BROWN ALGAE – EXAMPLE: KELP CAN GROW ABOUT 100 METERS) • RED ALGAE – SEE PICTURE TO RIGHT • GREEN ALGAE

THE ORIGIN AND EVOLUTION OF MICROBIAL LIFE • MULTICELLULAR LIFE MAY HAVE EVOLVED FROM COLONIAL PROTISTS