The Origin of Life & Evolution

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

http://science. discovery http://science.discovery.com/videos/100-greatest-discoveries-shorts-origin-of-life.html

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 Anaerobic respiration Energy + CO2 + H2O released Autotrophs  use CO2 & H2O  release O2 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

Homologous Structures Age of Earth Recent Fossil Finds Biogeography Evidence for Evolution Pgs. 465-471 Homologous Molecules Embryology Life’s Common Genetic Code

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 Traits develop NOT based on need Acquired traits cannot be passed on

The History of Evolution: Darwin 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 Natural Selection Don’t survive Survive! Pass on traits to next generation Traits not passed on Overall change in species: EVOLUTION

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 Gradualism Slow, constant change in species over time

Changes in Species Punctuated Equilibrium Long periods of time with little change in environment with short bursts with great change in species

Cladogram Determine similarities by comparing DNA sequences (gel electrophoresis)