Early+Earth+and+the+Origins+of+Life



(the first 3 A.S. on radioisotope dating are covered in this section)

Online study guide for IB-Biology Evolution section

Lecture notes for evolution here and here


 * 2/3/12**
 * evolution reassessment
 * read pg. 208-210 in book

HW:

 * study for human evolution test
 * read pg. 208-210


 * 2/6/12**

Human Evolution test, not including information on radioisotope dating
The vast amount of time that has passed since the formation of the earth is difficult for most people to grasp. The following link and image illustrate the stages in the developmental stages of the earth itself and the evolution of life from unicellular prokaryotes to complex multicellular organisms.

Geologic Time Virtual Dating (14C) K/ Ar dating tutorial __Image Legend__: Ma (million years); Ga (billion years)

Exploring the Origins of life Readings on Early Earth History (Website from O.S.U. Mansfield)


 * 2/7/12**

Radioisotope dating cont.,



During radioisotopic decay, 1 half-life = the time necessary for 1/2 of the original radioactive parent compound to decay to its daughter compound. In this example, Carbon-14 decays into Nitrogen-14 via beta-decay.

K-Ar dating:
 * Khan Academy**

C-14 dating:
 * Khan Academy video 1**
 * Khan Academy video 2**

Senior Capstone Release Day.
 * 2/8/12**

Conditions on Earth Four processes needed for the spontaneous origin of life on Earth What is life? How did life begin?
 * 2/9/12**

1. Assembly of simple organic molecules

Miller and Urey Experiment

Site of possible organic beginnings

Murchison meteorite

Some of the compound classes detected in the Murchison carbonaceous chondrite. The specific examples are amino acids ( l -alanine), carboxylic acids (propionic acid), hydroxyacids (lactic acid), sugar-related compounds (dihydroxyacetone), amines (propylamine), amides (pyroglutamic acid), nitrogen heterocycles (uracil), sulphur heterocycles (benzothiophene), aromatic hydrocarbons (2-methylnaphthalene), aliphatic hydrocarbons (pentane), terpenes (camphor). Note that by far the majority of organic matter in carbonaceous chondrites is present as a macromolecular material which contains some of these structures linked together, but is mostly made up of aromatic hydrocarbons.

Microfossils from the Murchison meteorite

HW: Go to the Miller and Urey Experiment website and conduct experiments to test the components necessary to form simple organic monomers. Reading: Chapter 4 from Raven, Johnson Text (Pages 62-63; 65-69).

Origin of self-replicating molecules Scientists develop self-replicating molecule in lab
 * 2/10/12**

RNA as the original hereditary molecule?
 * [[image:651px-Ribosome_mRNA_translation_en_svg.png width="432" height="306"]] || [[image:220px-RNA_chemical_structure.GIF width="272" height="267"]] ||

Protobionts (Coacervates and microspheres)
 * [[image:coacervates_image.jpg width="399" height="291" caption="Coacervates: lipid droplet enclosing organic molecules "]] || [[image:microsphere_image.jpg width="361" height="286" caption="microspheres: protein spheres surrounding organic moleculess"]] ||

HW: Read Chapter 4 (pages 70-76) from Raven, Johnson text.

Review? Radioisotope dating/origins of organic molecules/protobionts. RNA and the development of protobionts (for review, read the sections "Understanding the RNA World" and ""Building a Protocell".
 * 2/13/12**

__Evolution of prokaryotes__: From protobionts to prokaryotes This paper gives a good, if technical, description of the evolution of prokaryotes including archaebacteria and eubacteria during the early periods of Earth's development.

Archaebacteria vs. Eubacteria (Differences between archaebacteria and eubacteria)

**Archaebacteria** (video)
Definition //noun, singular: archaebacterium// [|Unicellular] [|microorganisms] in the [|domain] [|Archaea], which is genetically distinct from [|bacteria] and [|eukaryotes], and often inhabiting [|extreme] environmental [|conditions]. Examples of archaebacteria include [|halophiles] ([|microorganisms] that may inhabit extremely salty environments), [|methanogens] ([|microorganisms] that produce [|methane]), and [|thermophiles] ([|microorganisms] that can thrive extremely hot environments). They evolved separately from [|eubacteria] and [|eukaryotes]. They are similar to [|eubacteria] in being [|prokaryotes] and lacking distinct cell nuclei. They differ in terms of ribosomal structure, the possession of [|introns] and in [|membrane] [|structure] or [|composition]. They are similar to [|eukaryotes] such that [|archaea] possess [|genes] and several [|metabolic] [|pathways] that are more closely related to those of [|eukaryotes]: notably the [|enzymes] involved in [|transcription] and [|translation]. (//© Biology-Online.org.//)

Definition //noun, singular: eubacterium// Literally means true [|bacteria], which includes all [|bacteria] except for [|archaebacteria]. These [|bacteria] form the [|domain] [|Bacteria], previously called [|domain] Eubacteria. It is one of the three domain systems, the other two being [|domain] Archaeabacteria (now [|Archaea]) and [|domain] [|Eukarya] (the [|eukaryotes]). Eubacteria are [|prokaryotic] [|organisms], as characterized by the lack of a membrane-enclosed [|nucleus], predominantly [|unicellular], with [|DNA] in [|single] circular [|chromosome], and have [|peptidoglycan] on [|cell wall] when present. They include most of the familiar [|bacteria] of medical and economic importance such as //E. coli//, //Staphylococcus//, //Salmonella//, //Lactobacillus//, //Nitrosomonas//, //Streptomyces//, etc.(//© Biology-Online.org.//)
 * Eubacteria**



origin of cyanobacteria and evolution of photosynthesis development of an oxygen rich atmosphere
 * 2/14/12**
 * [[image:cyanobacteria_image.jpg width="450" height="303" caption="Images of a variety of cyanobacteria"]] || [[image:cyanobacteria_em_image.jpg width="342" height="292" caption="EM image of cyanobacteria structure"]] ||

origin of eukaryotes - development of organelles and nucleus from primitive infolding of bacterial membranes organelles and endosymbiosys video
 * [[image:origins_of_organelles_Page_02.jpg width="394" height="279"]] || [[image:origins_of_organelles_Page_01_Page_04.jpg width="406" height="299"]] ||
 * [[image:Mitochondria_image.jpg width="417" height="375"]] || [[image:chloroplasts_image.jpg width="387" height="263"]] ||

HW: Read the paper on evolution of prokaryotes. Bring questions to class tomorrow.

Online study guide for IB-Biology Evolution section
 * 2/15/12:** Test on radioisotopic dating and origins of life.