BIO 432 PROKARYOTIC DIVERSITY Prof Dr Sevgi ERTURUL

BIO 432 PROKARYOTIC DIVERSITY Prof. Dr. Sevgi ERTUĞRUL KARATAY

INTRODUCTION � Many physical and geological changes have occurred in the world since its formation � New conditions and changes occurred in the world after microbial life was formed � Microbial activities (metabolism and physiology) caused many changes in today's biosphere.

The origin of the world � 4. 5 billion years ago compared to slow-degrading radioactive isotopes � New star (sun) caused nuclear fusion-heat and light energy � World not suitable for life. . (500 million years)

� The water originated from volcanic gases and comets in the planet, but in the form of steam due to the temperature. � A rock that could show the age of the world could not be identified (due to geological changes) � One of the oldest sediment rocks 3. 86 billion years old have been found in southwest Greenland.

� Mineral zircon crystals were found in old samples (Zr. Si. O 4) � 4. 3 billion years ago it is believed that water concentrated in the form of the ocean � According to this, the world became suitable for life a few hundred million years after its formation.

Evidence of microbial life in the early World � Bacteria-like microfossils have been found in some old rocks (simple bacilli or cocci)

� Microbial formations called “stromatolite” are very common in 3. 5 billion years old rocks. � Stromatolite = fossilized filament prokaryote + stuck mineral material � Filamentous prokaryote = filamentous phototrophic bacteria, ancestors of example green sulfur-free bacteria Chloroflexus

In summary, microfossils show: 1. There was a microbial life within 1 billion years or earlier after the World was formed. 2. And even microorganisms began to differentiate morphologically

Hypothesis of Formation of Life on Earth The first cell, surrounded by membranes and self replicating, consists of a primitive soup rich in organic and inorganic compounds in a "warm little pond (Charles Darwin, On the origin of species). This hypothesis is not possible. Because of sudden temperature change, meteor crash, radiation etc. makes the formation hypothesis on earth impossible.

Formation hypothesis under the ground Conditions are more favorable and stable in hydrothermal hot water sources H 2 and H 2 S permanent and abundant energy source When very hot hydrothermal waters met ocean waters containing cold and Fe, “montmorillonite” clays containing Mg were formed. These are structures with a jelly, absorbent surface, semipermeable, closed and pores.

LUCA (Last Universal Common Anchestor) started with this very simple cell and evolved in two different directions (based on the physicochemical properties in the niches where they were most successful). Then these two populations were selected and today's cells were formed. Some details differed as these two lineages evolved