Biology 1202 Notes

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Thursday January 17
Mastering biology course id=MBPOLLACK01639
Life first appeared on earth about 4 billion years ago
Origin of life is a hypothesis not a theory
Very little oxygen in early earths atmosphere
Spontaneous generation of life- random formation of life
Millions of species on earth, up to 100 million
the expirement of miller and urey showed what? test question a few centuries ago:
people thought that new living things appeared all of the time(spontaneous generation of life) ex: mold growing on food in the mid 1800s Louis Pasteur refuted the theory of spontaneous generation of life he basically left something out but sealed it off and nothing grew on it, then he left it out without being sealed and stuff grew the cell theory- all existing cells come from pre-existing cells about 50 trillion cells make up the human body but all came from the single diploid cell formed from conception conditions on early earth:

atmosphere- similar to Jupiter today, no free oxygen, frequent storms with lots of lightning, volcano eruptions, meteor impacts, UV light from the sun, no ozone layer earth before life arose:
about 4.6 billion years old, known because of radiometric dating of meteorites and moon rocks
life arose about 3.8 billion years ago, known because of chemical traces in the rocks, fossilized bacteria was found in rocks 3.5 billion years ago
no spontaneous generation now but must have happened then
how to assemble a living thing:
accumulation of organic molecules
catalyze reactions
reproduce from stored genetic info
separate the living thing from the outside environment
3 domains of life- bacteria, archaea, eukarya
proteins are needed to synthesize more DNA
DNA is used to synthesize RNA which is used to make protein…DNA-RNA-Protein Ribozymes: RNA molecule that can catalyze reactions, especially those involved in synthesis and processing of RNA itself

Conclusion- earliest cells used RNA to store info
Ribozymes used to catalyze reactions

Thursday January 24th

Our species has been here for about 200,000 years
PRINCIPLES OF EVOLUTION
Theory- general explanation of natural phenomena, developed through extensive and reproducible observations Hypothesis- tentative explanation of observations, educated guess The origin of species was a book published in 1859 by Charles Darwin Main points of book:

Evolution occurs in populations, not individuals
Natural selection is the mechanism

Observation 1-living things tend to reproduce as quickly as possible. Observation 2-constant population size over time (carrying capacity) Inference- competition for survival; differential reproductive success “I don’t like dogs. They all smell like dogs and poop on my lawn” variability in structures and behaviors

all of this leads to natural selection, organisms best suited to an environment leave the most offspring evolution- the genetic makeup of a population changes over time, driven by natural selection evolution- a change in the allele frequency of a population over time study pakicetus slide

1/29/13

homologous structures suggest common ancestry
some homologous structures look different today because of divergent evolution 300 million years ago is when we started to see the type of mammalian limbs similar to the structure today analogous structures=convergent evolution

analogous structure do NOT suggest common ancestry
similar environmental forces select for similar structures in unrelated organisms vestigial structures- rudimentary form of and organ more fully formed in ancestor “evolutionary baggage” vestigial structures are a type of homologous structure

WHAT IS DARWINS POINT ON EAR? ON TEST
Developmental biology- the biology of studying organisms from the unicellular stage onward WATCH DARWIN VIDEO
All living things have DNA and transcribe it into RNA using amino acids Artificial selection- insecticides, antibiotics etc.
Know 3 types of natural selection
1.directional...
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