Lecture Set 4b: Bacteria, Archae, and Protists Chpt 16.

Lecture Set 4b:Bacteria, Archae, and Protists

Chpt 16

Early Earth (3.5 BYA)

• Atmosphere of carbon dioxide, hydrogen, sulfuric acid, water, ammonium and methane– No oxygen.– You would die in seconds– No FOOD!?!

• Kinda.• Chemicals to eat…

– Miller-Urey Experiment

The Earliest Organisms

• Bacteria and Archae capable of surviving without oxygen– Used chemical energy

from H-S bonds or C-H bonds.

Then came cyanobacteria…

• A real game-changer!– Started doing

photosynthesis, and creating oxygen

• Lots, and lots and lots of cyanobacteria creating lots and lots and lots of oxygen

• Whole oceans of just bacterial mats

• Enough to change the whole world’s atmosphere and chemistry!

Diversification of Prokaryotes

• Prokaryotes ruled the world for 2.5 billion years, or so.– Became different,

diverse, and successful.

• Some evolved cell walls with peptioglycan– Eubacteria

• Some evolved histones and introns– Archae

Eubacteria

• Such as cyanobacteria, staphylococcus, streptococcus, E. coli, etc.– Have a cell wall with

peptidoglycan– The most successful

organisms on Earth!– Have endospores

• Allows them to survive in stasis until better conditions come along

Plasmids

• Small rings of DNA not part of the chromosome

• Can be exchanged to other bacteria via pilli

Archae

• No peptidoglycan, but histones (in some species), introns, a more complex RNA polymerase– Shares traits with Eukaryotes– Believed to evolved into

Eukaryotes

• Most are extremophiles– Like environments with high

heat, methane, salt, etc.

Eu

The origin of Eukaryotes

• The first Eukaryotes appeared– ~2 BYA– Descended from Archae– Protists

• Single celled, then colonies of single-celled, then multicellular

Protists

• Protozoans– “Animal-like” before animals

• Algae– “plant-like”– Kelp, sea weed, etc

• A large assortment of other things not plants, animals, or fungi

Protists

• Slime Molds

• Kelp

• Amoebas

• Sea Weed

• Dinoflagellates

• Radialarians

• Etc..