Chapter 4 THE ORIGIN AND EARLY HISTORY OF LIFE

FUNDAMENTAL PROPERTIES OF LIFE CELLULAR ORGANIZATION SENSITIVITY GROWTH DEVELOPMENT REPORDUCTION REGULATION HOMEOSTASIS HEREDITY –Is this the same list as in chapter 1?

Where did it all start? Special Creation Extraterrestrial Origin- Panspermia Spontaneous Origin The Scientific Viewpoint

What Was Early Earth Like? Very Hottttttttttt Composition of Earth Debatable –Many think that it was a reducing atmosphere- with CO2, N2, H20 and H2

Where Did Life Form? It is believed that the first precurses to life formed between 3.8 and 2.5 billion years ago….but where? Oceans edge? Under frozen oceans? Deep in earths crust? Within clay? In deep sea vents?

ET PHONE HOME??? Scientists are beginning to think life does exist in outer space. –Mars Rock Evidence –Other Planets

Stanley Miller and Harold Urey

What came first RNA or Proteins? Huge Debate RNA people say that without a hereditary molecule other molecules could not be formed Protein group says that without enzymes nothing could replicate at all. Peptide-Nucleic Acid people say that there must have been a pre-RNA world where the protein- nucleic acid was the basis for life

Oparin’s Bubble Hypothesis Says that in order for cells to develop they must have had some type of “protection” Protobionts Figure 4.8

The Earliest Cells Microfossils- suggest that first cells prokaryotes, earliest eukaryotes about 1.5 billion years ago. Archeabacteria- live in very harsh environments lack peptidoglycan –Methanogens, thermophiles, halophiles Bacteria- have very strong cell walls- cyanobacteria very important

Eukaryotes Indirect evidence suggests that they might go back 2.7 billion years…but no direct fossil evidence for this. So how did Eukaryotes come to be???? –Origin of the Nucleus and ER –Origin of Mitochondria and Chloroplasts Endosymbiosis theory supported by the fact that both Mitochondrion and Chloroplasts have their own DNA similar to that of free living bacteria

Evolution of the Eukaryote

Advantages of being Eukaryotes? Sexual Reproduction Multicellularity

Classification of Organisms Linnaeus- came up with the binomial way of naming organisms Homo sapiens –Homo= genus, is capitalized and italicized –Sapiens= Species, lower case and italicized

Three Domains of Life

Features of the Domains of LIfe FeatureArchaeaBacteriaEukarya Amino acid that initiates protein synthesis MetFormyl- metMet IntronsPresent in some genes AbsentPresent Membrane-bound organelles Absent Present Nuclear EnvelopeAbsent Present Peptidoglycan in cell wall AbsentPresentAbsent Response to Antibiotics streptomycin and chloramphenicol Growth not inhibited Growth InhibitedGrowth not inhibited Number of different RNA Polymerases SeveralOneSeveral

6 Kingdoms

Evolution of the 6 Kingdoms

Characteristics of the 6 Kingdoms Part 1

Characteristics of the 6 Kingdoms Part 2

What about Viruses? They are a special case They can not survive on their own so they are not considered “Living” They are parasitic Chemicals