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| The backbone of life, has the ability to form large complex and diverse molecules. E.g. proteins, DNA, lipids, carbohydrates, ext... |
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| Organic chemistry is the study of compounds that containing carbon. |
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| the idea that organic compounds arrise only organisms. In 1953 disproved by Stanley Miller |
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| is the view that all natural phenomena are governed by physical and chemical laws |
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| Carbon Valence electrons can form four covalent bonds with a variety of atoms including itself. |
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| tetravalence and flat shapes depending if its single or double bonded.This makes large , complex molecules possible |
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| Carbons most frequent partners |
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| Hydrogen, Oxygen and Nitrogen |
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are organic molecules consisting of only carbon and hydrogen.
-Many organic molecules, such as fats have hydrocarbons.
-Can undergo reactions that release a large amount of energy. |
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| Are compounds with the same molecular formula but different structures and properties:1.Structural 2.Geometric 3. Enantiomers |
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| Structural Isomers have different covalent arrangements of their atoms. |
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| Geometric isomers have the same covalent arrangements but differ in spatial arrangements |
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| Enantiomers are isomers that are mirror images of each other. |
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the key to biological molecule interactions.
-Distinct properties include 1. carbon skeleton 2. molecular components attached to it |
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| The seven functional groups that are most important |
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| 1.hydroxyl 2. carbonyl 3. Carboxyl 4. Amino group 5. Sulfhydryl 6.Phosphate group 7. ethyl group |
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| ATP: The rechargeable battery of the cell |
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| One phosphate molecule, adenosine triphosphate, is the primary energy-transfering molecule in the cell. |
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| ATP consists of an organic molecule called adenosine attached to a string of three phosphate groups. |
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| Chemical and physical processes on early Earth may have produced very simple cells through a sequence of stages: |
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Abiotic synthesis of small organic molecules
Joining of these small molecules into macromolecules
3. Packaging of molecules into “protobionts”
4. Origin of self-replicating molecules |
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| Abiotic synthesis of small organic molecules |
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Earth’s early atmosphere likely contained water vapor and chemicals released by volcanic eruptions (N, CO2, CH4, NH4, H2, H2S, etc)
Oparin and Haldane hypothesized that the early atmosphere was a reducing environment (1920s)
Miller and Urey showed that the abiotic synthesis of organic molecules in a reducing atmosphere is possible (1953) |
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| Joining of small molecules into macromolecules |
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| Small organic molecules polymerize when they are concentrated on hot sand, clay, or rock |
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Protobionts are aggregates of abiotically produced molecules surrounded by a membrane or membrane-like structure
Protobionts exhibit simple reproduction and metabolism and maintain an internal chemical environment |
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| Experiments demonstrate that protobionts |
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protobionts could have formed spontaneously from abiotically produced organic compounds
For example, small membrane-bounded droplets called liposomes can form when lipids or other organic molecules are added to water |
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| Origin of self-replicating molecules |
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The first genetic material was probably RNA, not DNA
RNA molecules called ribozymes have been found to catalyze many different reactions
e.g., ribozymes can make complementary copies of short stretches of their own sequence or other short pieces of RNA
The early genetic material might have formed an “RNA world” |
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| Importance of the fossil record |
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The fossil record reveals changes in the history of life on earth
Sedimentary rocks are deposited into layers called strata and are the richest source of fossils |
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| The fossil record is biased in favor of species that |
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Existed for a long time
Were abundant and widespread
Had hard parts |
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| How Rocks and Fossils Are Dated |
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Sedimentary strata reveal the relative ages of fossils
The absolute ages of fossils can be determined by radiometric dating
A “parent” isotope decays to a “daughter” isotope at a constant rate
Each isotope has a known half-life, the time required for half the parent isotope to decay |
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| is divided into the Archaean, the Proterozoic, and the Phanerozoic eons |
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| origins of single-celled organisms |
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Archaean Eon – prokaryotes
Early Proterozoic – eukaryotes |
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| Middle of Proterozoic Eon |
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| rock-like structures composed of many layers of bacteria and sediment (3.5 billion years ago) |
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| The First Single-Celled Organisms |
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| Stromatolites and Prokaryotes were Earth’s sole inhabitants from 3.5 to about 2.1 billion years ago |
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Posed a challenge for life
opportunity to gain energy from light
Allowed organisms to exploit new ecosystems |
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| mitochondria and plastids (chloroplasts and related organelles) were formerly small prokaryotes living within larger host cells |
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| is a cell that lives within a host cell |
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| mitochondria evolved before plastids through a sequence of endosymbiotic events |
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| Key evidence supporting an endosymbiotic origin of mitochondria and plastids: |
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Similarities in inner membrane structures and functions
Division is similar in these organelles and some prokaryotes
These organelles transcribe and translate their own DNA
Their ribosomes are more similar to prokaryotic than eukaryotic ribosomes |
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| The Origin of Multicellularity |
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A second wave of diversification occurred when multicellularity evolved and gave rise to algae, plants, fungi, and animals
Comparisons of DNA sequences date the common ancestor of multicellular eukaryotes to 1.5 billion years ago |
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| refers to the sudden appearance of fossils resembling modern phyla in the Cambrian period (535 to 525 million years ago) |
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| The Cambrian explosion provides |
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| the first evidence of predator-prey interactions |
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Fungi, plants, and animals began to colonize land about 500 million years ago
Plants and fungi likely colonized land together by 420 million years ago
Arthropods and tetrapods are the most widespread and diverse land animals
Tetrapods evolved from lobe-finned fishes around 365 million years ago |
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| In the history of life on Earth, the rise and fall of many groups of organisms reflects: |
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continental drift
mass extinctions
adaptive radiations |
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| Consequences of Continental Drift |
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Formation of the supercontinent Pangaea about 250 million years ago had many effects
A reduction in shallow water habitat
A colder and drier climate inland
Changes in climate as continents moved toward and away from the poles
Changes in ocean circulation patterns leading to global cooling |
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The fossil record shows that most species that have ever lived are now extinct
At times, the rate of extinction has increased dramatically and caused a mass extinction
In each of the five mass extinction events, more than 50% of Earth’s species became extinct |
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| Consequences of Mass Extinctions |
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1.can alter ecological communities and the niches available to organisms
2.can take from 5 to 100 million years for diversity to recover following a mass extinction
3.can pave the way for adaptive radiations |
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| is the evolution of diversely adapted species from a common ancestor upon introduction to new environmental opportunities |
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