MicrobiologyBytes: Introduction to Microbiology: Origins of Life Updated: January 19, 2005 Search

The Origins of Life:
Prebiotic Evolution and the Precambrian Fossil Record

Our expanding universe formed around 15 billion years ago (1 billion years is 109 years), in a few seconds from elemental particles in the 'Big Bang'.

Element synthesis up to 56Fe occurs in main sequence stars.

Elements heavier than Fe are synthesized in supernovae:

The solar system and the earth are around 4.6 billion years old.

The oldest rocks on earth date back to 3.8 - 4.0 billion years.

Original atmosphere on earth 'reducing': CO2, N2, H2, CO, H2O + trace amounts of NH3, CH4 (Oparin, Haldane).

Energy input - UV, cosmic rays, radioactivity etc. on the early earth:

The experiments of Stanley Miller:

Abiogenic synthesis of most 'building blocks' e.g. Strecker synthesis:

                                   H2O
 RCHO + HCN + NH3 == RCH (NH2) CN ----->

                    H2O
 RCH (NH2) CO - NH2 ----> RCH (NH2) COOH

Synthesis elsewhere in universe - Hoyle and Wickramasinghe.

Molecules in interstellar space - HCN, HCHO, H2NCN etc.

Problems:

(a) Chirality
(b) Polymerisation
(c) Energy system
The chicken and the egg, which came first? DNA vs. RNA vs. protein.

Ribozymes and the RNA world?

Catalytic function of RNA:

Membrane acquisition:

From the first protobiont to the first prokaryote - when?

The Geological Timetable:

ERA: PERIOD: EPOCH: AGE (millions of years ago): EVENTS:
  Quaternary Recent 0.01 Historic time
Pleistoceine 2.5 Ice ages; humans appear
CENOZOIC Tertiary Pliocene 7 Ape-like ancestors of modern humans
Miocene 25  
Oligocene 38 Origins of most modern mammals
Eocene 54  
Paleocene 65  
MESOZOIC   Cretaceous 135 Flowering plants appear; dinosaurs extinct
Jurassic 190 Conifers, mammals & birds appear; dinosaurs dominant
Triassic 235 Mammal-like reptiles appear
Permian 280 Origin of most modern orders of insects
Carboniferous 345 Origin of reptiles; amphibians & bony fishes dominant; first seed plants
PALEOZOIC   Devonian 395 First land plants
Silurian 450  
Ordovician 500 First vertebrates
Cambrian 570 Origin of most invertebrates
PRECAMBRIAN     4600 Approximate age of the earth

Bestsellers - Music - DVDs - Videos - Electronics
Search for ... (keywords):
Search for ... (keywords):

Bestsellers - Music - DVDs - Videos - Electronics

Fossil discontinuities:

Stanley Tyler and the birth of micropalaentology.

Stromatolites and the stromatolithic cherts.

Major Precambrian fossil sites:

Appearance of oxygen in the atmosphere - red beds.

Completion of element cycles.

Appearance of eukaryotes, 'acritarchs'.

Colonization of land.

HOW DID EUKARYOTES ARISE?

CoverMicrobiology
by L.M.Prescott et al.
A balanced, comprehensive introduction to all major areas of microbiology. The sixth edition has been updated extensively to reflect the latest discoveries in the field.
(Amazon.co.UK)

Search for more information on this topic

© MicrobiologyBytes 2007.