early earth and the origin of life. major episodes isotopes of carbon
TRANSCRIPT
EARLY EARTH and the
ORIGIN OF LIFE
Major Episodes
Isotopes of carbon
•Life on Earth: 3.5-4.0 billion years
•Prokaryotes: 3.5 billion•stromatolites
•Oxygen: 2.7 billion•Cyanobacteria
•Eukaryotes: 2.1 billion
•Multicellular Eukaryotes: 1.2 billion
•Animal Diversity: Cambrian period
•Land plants: 500 million
Cambrian Explosion
THE ORIGIN OFLIFE
• Spontaneous generation
• Biogenesis
•Louis Pasteur
Miller & Urey
Primitive Atmosphere
•H2O•H2
•CH4
•NH3
•Formation of organic monomers – first step in origin of life
RNA may have been the first self replicating genetic material.
•Replication & ribozymes (RNA autocatalytic)•Natural selection (genotype & phenotype)
PROTOBIONTS – aggregates of abiotically producedmolecules
liposome
RNA template for polypeptide formation
Polypeptides act as primitiveenzymes that aid replication
of all RNA molecules, includingcompeting RNAs
FIVE KINGDOM SYSTEM
Kingdom Characteristics – must know!
PROKARYOTES
AND THE ORIGINS OF
METABOLIC DIVERSITY
PROKARYOTES
extremophiles
eubacteria
STRUCTURE & FUNCTION
Shape: cocci (spherical), bacilli (rod), spirilla (helical)
Diplo- (2), strepto- (chain), staphylo- (cluster)
Peptidoglycan (modified sugars cross-linked by short polypeptides) in cell walls
Gram stain: Gram+ (simpler walls, thick peptidoglycan) Gram- (more complex, less peptidoglycan)
Capsule: protective layer outside wall, sticky
Pili: surface appendages
Motility: flagella, spirochetes (corkscrew,) slimy threads
Taxis: movement toward or away from stimulus
ORGANIZATION & REPRODUCTION
Specialized membranes
Nucleoid region
Plasmids*
Binary fission
Transformation Conjugation Transduction Endospores Antibiotics
Nutritional Diversity:•Saprobes•Parasites•Metabolism of petroleum•Nonbiodegradable (synthetic organic compounds)
Nitrogen Metabolism:•Nitrogen fixation•N2 NH4
•Cyanobacteria
Oxygen use:Obligate aerobesFacultative anaerobesObligate anaerobes
EXTREMOPHILES•Methanogens•Extreme halophiles (bacteriorhodopsin•Extreme thermophiles
ECOLOGICAL IMPACT
Decomposers Symbiosis Mutualism Commensalism Parasitism
Pathogenic Koch’s Postulates Exotoxins Endotoxins Bioremediation
THE ORIGINS OF
EUKARYOTIC DIVERSITY
Characteristics
Eukaryotic, unicellular, colonial, multicellular
Nutrition: aerobic, photoautotrophs, heterotrophs, mixotrophs
Ingestive (protozoa), photosynthetic (algae), absorptive (fungus like)
Motility: flagella, cilia, psuedopodia Life cycles: asexual (mitosis), sexual
(meiosis & syngamy), cysts Habitat: aquatic (plankton) & moist
terrestrial areas, contractile vacuoles
EUGLENA - MIXOTROPH
ENDOSYMBIOSIS
EVOLUTIONARY TRENDS:1) Filamentous Cyanobacteria – specialized cells2) Complex communities –species w/ metabolic specialties3) Compartmentalization within cells eukaryotes
PRIMARY & SECONDARY ENDOSYMBIOSIS
Diplomonadida and Parabasala
lack mitochondria
Giardia lamblia Trichomonas vaginalis
Euglenozoa • both photosynthetic and heterotrophic flagellates
Euglena - mixotrophic
Trypanosoma –African sleeping sickness
Alveolata
• unicellular protists with subsurface cavities (alveoli)
• Dinoflagellates: red tides (deadly toxins) Gonyaulax
• Ciliates: paramecium, stentor
• Apicomplexans: all parasitic, plasmodium - malaria
Stramenopila• The stramenopile clade includes the water molds and the heterokont algae
Oomycota Water mold
Diatoms: glass like cell wallsChrysophytes:
Golden algae
Phaeophytes: brown algae,Seaweeds (kelps)
SEAWEEDS•Structural and biochemical adaptations help seaweeds survive and reproduce at the ocean’s margins •Food source, thickening agents, agar •Some algae have life cycles with alternating multicellular haploid and diploid generations
Rhodophyta: Red algae lack flagella
Most abundant large algae in warm coastal watersof tropical oceans
Chlorophyta• Green algae and plants evolved from a
common photoautotrophic ancestor
• Unicellular (chlamydomonas), colonial (volvox), filamentous (spirogyra), multicellular (ulva)
• Lichens
A diversity of protists use pseudopodia for movement and feeding
Rhizopoda: amoebas, amoebic dysentery
Actinopoda (Heliozoan & Radiolarians)
Foraminiferanscalcium carbonate walls, limestone fossils, Dover cliffs
Mycetozoa: Slime molds have structural adaptations
and life cycles that enhance their ecological roles
as decomposers
Plasmodial Slime Mold
FUNGI: CHARACTERISTICS
EukaryoticMulticellularHeterotrophs (absorptive – digestion outside body)
Cell walls of chitinClassified by sexual stage (fruiting body)
Function – obtaining food
Haustoria – hyphae of parasitic fungi modified to penetrate and absorb nutrients from host tissue
Example - Rhizopus
*PENICILLIUM
LICHENS
MYCHORRHIZAEMutualistic
Involve?