catalyst 5 minutes to complete, extra credit to finished on thursday’s test what do you think the...
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Catalyst5 minutes to complete, extra credit to finished
on Thursday’s Test
What do you think the word ‘Evolve’ means?
What are dinosaurs closest ancestors?
AnnouncementsTest on Thursday!
Review on Wednesday (this will be fun )
Tutoring for test changed to Wednesday afternoon
Origins of LifeDecember 16th , 2012
Original IdeaOnce thought that life came
from spontaneous generatio, meaning life came from nonliving things. This is abiogenesis.
DisprovedRedi’s experiement tested
whether maggots (living things) spontaneously generated from meat (dead tissue)
Remi
PasteurThis scientists used beef broth
to prove that microorganisms (bacteria)
Remi and Pasteur’s experiments proved
biogenesis
So… if life has to come from living things, how did life first start?Atmosphere of earth Earth
contained gasesGases reacted with enery from
lightening to produce small organic molecules (amino acids)
In the 1950’s Miller and Urey filled a flask with hydrogen, methane, ammonia, and water to represent the early Earth and they used electric lightning to stimulate the mixture. In a few days, organic compounds had formed! This suggested that life can be made from simple compounds on the primitive earth
Miller and Urey
Evolution of CellsThe first true cells were heterotrophic prokaryotes
They evolved the ability to do photosynthesis to make their own food
Photosynthetic prokaryotes were responsible for the release of oxygen into the atmosphereOxygen was toxic to many organisms who died off
Eukaryotic cells probably arose through a symbiotic relationship between two kinds of prokaryotic cells: We believe that mitochondria and chloroplasts used to be prokaryotes (They have their own DNA)!A photosynthetic bacteria (future chloroplast) and an
aerobic heterotroph (future mitochondria) found their home inside the cells
EvolutionThe diversity of life on earth may
be understood through the study of evolution.
Evolution – the gradual change in the characteristics of a species over time.
Species – a group of organisms whose members look alike and successfully reproduce among themselves.
What is the origin of the concept of evolution?
Fossils interested scientists in evolution.
Evidence for Evolution1. Fossils show changes over time.
-Fossils provide a record for earlier life.
2. Anatomical relationships – similarities in the structure of an organism. Evidence that organisms evolve from a common ancestor.
Homologous structure are body parts that are similar in structure, in function, or in both structure and function.
Homologous Structures
Analogous structures are body parts that are similar in function, but different in structure.
ex. Wings of a bird and a butterfly
Vestigial structures any body structure that is reduced in function.
May have been of use to an ancestor.ex. flightless birds (ostrich),
appendix in humans
3. Embyological Development shows evolution from a common ancestor.
ex. The presence of gills and tails in the early stage of all vertebrate embryos.
4. Genetic Comparisons may also show relationship of different species. Can also helps us tell how closely related or how different species are
ex. Order of DNA and RNA nucleotides
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