Biology 1202B Lecture Notes - Cyanobacteria, Reverse Transcriptase, Photosynthesis

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30 Apr 2012
Lecture 1
Characteristics of Living Things:
o They are complex and highly organized
o They have the ability to take energy from the environment and change it from one form
to another
o They tend to be homeostatic can regulate their body and other internal structures
o They respond to stimuli
o They reproduce
o They grow and develop
o They adapt and evolve in step with external changes in their environment
Drake Equation calculates the probability of other planets having living civilizations in our
Universe formed 15 billion years ago (Big Bang)
o Galaxies formed from stars, dust and gas
o Earth formed 4.6 billion years ago
o Oldest fossils formed 3.5 billion years ago
o Eukaryotic fossils formed 2.2 billion years ago
Cell Theory:
o All organisms are composed of one or more cells
o The cell is the smallest unit that has all the properties of life
o Cells arise only from the growth and division of pre-existing cells
Oparin/Haldane organic molecules could be made in the absence of life
o Early atmosphere was a reducing atmosphere (no free oxygen)
o But, there was free hydrogen and hydrides (Ex: CH4)
o There was lots of energy from electric discharges in storms and solar energy (no ozone)
o Also, the Earth’s surface temperature was probably hotter than today
o These all allow lots of reactions to occur
Miller/Urey Experiment simulated conditions similar to ones believed to be in the early
o Obtained urea, amino acids, nucleotides and formic/lactic/acetic acids
Panspermia asteroids and comets could have brought organic matter to Earth
Amino acids changing to polypeptides could have occurred when dry or highly concentrated
monomers are heated
o Condensation reactions (when components of water molecules are removed) create
peptide bonds between amino acids or phosphodiester bonds form between
o Polysaccharides (Ex: glucose)
o Proteins (Ex: amino acids)
o Nucleic acids (Ex: nucleotides)
Catalysts speed up a reaction without affecting itself
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