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The Nature and Classification of Life OCN 626 Marine Microplankton Ecology Lecture 1 What is Life? General Defining Features Of Life: • Self-replicating • Responsive, Adaptable • Controlled transformations of matter and energy • Self-Replication • Self-Repair • Maintenance of disequilibrium Components of Life as We Know it Life on earth today: • Cellular • Carbon-based • DNA, RNA, Protein, Lipid, Carbohydrate Building Blocks • Sugars (Carbohydrates) Structural Polysaccharides Glucose (Monosaccharide) Sucrose (Disaccharide) Building Blocks • Nucleotides (4) -> DNA & RNA Informational + Structural (RNA) Building Blocks • Amino Acids (20) -> PROTEINSStructural Examples: Catalytic Building Blocks • Lipids -> membranes Structural Relative Mass of Elements in the Human Body Element Atomic number Percentage Role oxygen 8 65 cellular respiration, component of water carbon 6 18.5 basis of organic molecules hydrogen 1 9.5 component of water & most organic molecules, electron carrier nitrogen 7 3.3 component of all proteins and nucleic acids calcium 20 1.5 component of bones and teeth, triggers muscle contraction phosphorus 15 1 component of nucleic acids, important in energy transfer potassium 19 0.4 main positive ion inside cells, important in nerve function sulfur 16 0.3 component of most proteins sodium 11 0.2 main positive ion outside cells, important in nerve function chlorine 17 0.2 main negative ion outside cells magnesium 12 0.1 essential component of many energy-transferring enzymes iron 26 trace essential component of hemoglobin in the blood copper 29 trace component of many enzymes molybdenum 42 trace component of many enzymes zinc 30 trace component of some enzymes iodine 53 trace component of thyroid hormone Origin of Life on Earth Panspermia Divine Creation Chemical Evolution Origin of Life on Earth •Difficult task! Must combine knowledge of: of conditions on early •History earth •Chemical nature of life to make logical inferences about what happened in the very (very) distant past 1: macromolecules; the building blocks • Step of life The Miller-Urey Experiment H2O Methane Ammonia Hydrogen SPARK Gas (Atmosphere) Amino Acids & other organic Compounds COOL Water (Ocean) HEAT Many building blocks of life are easy to make • Many variations on Miller-Urey experiment have had similar results • Meteorites and comets found to contain organic compounds similar to those produced in the Miller experiment Murchison Meteorite ≥ 90 amino acids and other organic compunds Wild 2 Molecules to Life • Large gap to overcome from organic molecules to self-replicating entities • Life forms today are complicated machines Copyright M.W. Davidson and Florida State University Research Foundation Evolution and Classification of Life Frogfish A Fundamental Division With Nucleus No Nucleus Unicellular LUCA Uni- or MultiCellular Classification of Life • Prokaryotes (no nucleus) • Bacteria • Archaea DNA DNA • Eukaryotes (with nucleus) • All other living things DNA Organelles Serial Endosymbiosis Theory • Eukaryotes arose through the merger of multiple prokaryotic cells Aerobic Bacteria Photosynthetic Bacteria Archaea Anaerobic Bacteria Eukaryote Photosynthetic Eukaryote Animals Plants Is There a LUCA? Protista Prokaryotae http://universe-review.ca/I10-01-FiveKingdom.jpg Classification by Evolutionary Relationship • Domain (Eukaryota) • Kingdom (Animalia) • Phylum (Chordata) • Class (Mammalia) • Order (Primata) • Family (Hominidae) • Genus (Homo) • Species (sapiens) Most Life on the planet is Microscopic! LUCA Microscopic And Most Life in the Sea is Microscopic! Small Flagellate Prokaryote Large Flagellate Diatom http://www.cellsalive.com/howbig.htm Classifying Marine Organisms by Nutrition • Autotrophs - use CO • • 2 to make organics All plants, some protista and bacteria Can use sunlight (photo-) or chemical (chemo-) energy • Every other living thing - Need to consume organic • Heterotrophs compounds • Mixotrophs - They can do both! Prokaryotes Photoautotrophs Chemoautotrophs Heterotrophs Mixotrophs Protista Photoautotrophs Heterotrophs Mixotrophs Fungi Heterotrophs* Plantae Photoautotrophs * Animalia Heterotrophs* Autotrophy Energy 6 CO2 + 6 H 2O Autotrophic Cell C6H12O6 + 6 O2 Sugar Cells are more than sugar. Other compounds are built from simple sugars plus nutrients (Nitrogen, Phosphorous & trace metals) Respiration All living things respire..including plants! Energy (heat) (chemical) 6CO2 + 6H2O Waste Products Excretion Heterotrophic Cell C6H12O6 + 6O2 Biomass Growth Classifying Marine Organisms by Habitat • Benthic (benthos = bottom) • Pelagic (pelagius = of the sea) Physical Divisions of the Marine Environment Supralittoral (splash zone) NERITIC OCEANIC Epipelagic Mesopelagic Littoral (intertidal) Sublittoral 200 m 1000 m Bathypelagic Bathyal 4000 m Abyssal Hadal Abyssopelagic Hadalpelagic 6000 m Classifying Marine Organisms by Lifestyle • •Benthic (benthos = bottom) • Infauna Epifauna • •Pelagic (pelagius = of the sea) • Plankton (Drifters, weak swimmers) Nekton (Swimmers) Benthic Organisms Epifauna Epiflora Infauna Pelagic Organisms 35 mm Nekton (all are animals) Plankton phytoplankton zooplankton (holo- vs. mero-) prokaryoplankton 5 mm Classification by Size Size vs Abundance These curves continue to go up DRAMATICALLY at even smaller sizes. For example, for prokaryotes, at about 1 micrometer length , the abundance is about 1,000,000,000,000 per cubic m! Russell Hopcroft http://alph a.es.umb.edu/faculty/mzh/files/web-opc/OPCtheory.htm
