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The Origin of Life
• Heterotroph Hypothesis: 1st organisms were heterotrophs
• Conditions– Raw materials: H2, NH3, CH4, H2O
– Temperature: VERY HOT!– Other energy sources: Lightening, solar
radiation, volcanos
Origin of Life: Results of Experiment
• Synthesis Reaction!– “Build” aggregates (clumps) of simple sugars
& amino acids• Amino acids building blocks for proteins!
• “Reproduction”- amino acids split
• Lead to simple single celled organisms
Origin of Life: Cont’d
1. Anaerobic respiration– Energy + CO2 + H2O
released
2. Autotrophs use CO2 & H2O release O2
3. Aerobic Respiration Use O2 & glucose release CO2
Evolution
• Evolution- process of change over time
• Theory of organic evolution– Compare existing to previous forms of life
Evidence for Evolution
Age of Earth Recent Fossil Finds Homologous Structures
Embryology Life’s Common GeneticCode
Homologous Molecules
Biogeography
Pgs. 465-471
The History of Evolution: LaMark
• LaMark (1802)- “Changes occur in species for their improvement”
• Develop traits due to a need for them– Example: Giraffes grow tall
necks because they need to reach leaves at the tops of trees
• Transmission of acquired characteristic– If a trait is acquired, it will be
passed on
• Evolution– Add up all characteristics,
there is overall change
The History of Evolution: Weismann
• Weismann – Traits develop NOT based on need– Acquired traits cannot be passed on
The History of Evolution: Darwin
• Darwin (1854)– Adaptations: Traits
that enable an organism to survive within a specific niche
– Natural selection• Survival of fittest• The driving force
behind evolution
– Transmission of favorable characteristics
• Pass on adaptations to next generation
Variation in species (adaptations)
Competition & Environmental Conditions
Survive!
Pass on traits to next generation
Don’t survive
Traits not passed on
Overall change in species:EVOLUTION
Natural Selection
The History of Evolution: DeVries
• DeVries (1886): “Variation is the result of mutation”
• Results from:– Random mutation– Sexual reproduction
• Meiosis/Gamete formation• Different DNA!
Modern Theory of Evolution
• Sources of variation– Random mutation– Sexual reproduction
• Meiosis/gamete formation• Differing DNA transferred to next generation
• Natural selection– Survival of the fittest– Influences how quickly species adapt
Modern Theory of Evolution: Cont’d
• Rate of Evolution Relies on Environment– Unchanging/Stable Environment
• Favored traits passed on• Unfavored traits not passed on• Slow adaptation
– Changing/Unstable Environment• High turnover for survival of fittest• Must continue to adapt to changing
environment• Limited resources
Changes in Species
• Punctuated Equilibrium– Long periods of time with little change in
environment with short bursts with great change in species