Prokaryotes and Protists CH 16

PROKARYOTES Prokaryotes have inhabited Earth for billions of years Prokaryotes are the oldest life-forms and remain the most numerous and widespread organisms Colorized SEM 650  Figure 16.7

First Cells RNA might have acted as templates for the formation of polypeptides Assisted in RNA replication Self-replication of RNA Self-replicating RNA acts as template on which poly- peptide forms. Polypeptide acts as primitive enzyme that aids RNA replication. RNA Polypeptide Membrane-enclosed molecular cooperatives may have preceded the first cells

Membranes may have separated various aggregates of self-replicating molecules which could be acted on by natural selection LM 650 Membrane Polypeptide RNA Figure 16.6B, C

Prokaryotes Small, relatively simple cells Do not have a membrane-bound nucleus Figure 4.3B

Branches of Prokaryote Evolution Bacteria and Archaea Distinguished on the basis of nucleotide sequences and other molecular and cellular features

Prokaryote Shapes Cocci Bacilli Spirochetes

Structural Features Gram staining Gram + (purple) Gram – (pink) Cell wall differences Gram + (purple) Simple cell wall Thick peptidogylcan layer Gram – (pink) More complex cell wall with lipids bonded to carbohydrates Thin peptidoglycan layer

Structural Features Capsule Pili Flagella

Growth & Reproduction Binary Fission Endospore

Innards Lacks membrane bound organelles Respiratory / photosynthetic membrane Small, circular genome Ribosomes

Nourishment Phototrophs & Chemotrophs Autotrophs & Heterotrophs Biofilms Energy source Light Chemical CO2 Photoautotrophs Chemoautotrophs Carbon source Photoheterotrophs Chemoheterotrophs Organic compounds

Archea Extremes Extremophiles Halophiles Thermophiles Methanogens

Bacteria Proteobacteria Chlamydias Spirochetes Gram-positive bacteria Cyanobacteria

Disease Exotoxins Endotoxins

Bacteria Uses Biological weaponry Bioremediation

Bioremediation Recycle chemicals and clean up the environment Prokaryotes are decomposers in Sewage treatment and can clean up oil spills and toxic mine wastes Liquid wastes Outflow Rotating spray arm Rock bed coated with aerobic bacteria and fungi Is the use of organisms to clean up pollution Figure 16.16A, B

Protists are an extremely diverse assortment of mostly unicellular eukaryotes Colorized SEM 4,000  The parasitic Giardia Plasmodium causes malaria Red blood cell Apex TEM 26,000 Single celled algae SEM 2,300

Protists and Evolution Multicellularity evolved in several different lineages probably by specialization of the cells of colonial protists Unicellular protist Colony Early multicellular organism with specialized, interdepen- dent cells Later organism that produces gametes Food- synthesizing cells Locomotor cells Somatic cells Gamete 1 2 3

Symbiosis Endosymbiosis Secondary endosymbiosis Green alga Remnant of Nucleus Secondary endosymbiosis Chloroplast Euglenozoans Cyanobacterium Remnant of red alga Primary endosymbiosis Autotrophic eukaryotes Heterotrophic eukaryotes Example of symbiosis- jelly fish of salt water lakes in Palou Nucleus Dinoflagellates Heterotrophic eukaryote Evolved into chloroplast Secondary endosymbiosis Apicomplexans Nucleus Chloroplast Red alga Stramenopiles

Protists Diplomanads Euglenozoans Alveolates Parabasalids Dinoflagellates Ciliates Apicomplexans

Protists Stramenopiles Amoebozoans Watermolds Diatoms Brown Algae Feed via pseudopodia Plasmodial slime mold Plasmodium Cellular slime molds

Protists Foraminiferans Radiolarians Algae Red Green