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?