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Lecture 1

BIOL 1202 Lecture Notes - Lecture 1: Spark Chamber, Louis Pasteur, Purified Water

Biological Sciences
Course Code
BIOL 1202

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I. Earth
a. The universe is 14 - 16 billion years old
b. We have been on earth about 200,000 years
i. Charles Darwin published his book in 1859
II. Cell Theory
a. 50 trillion cells make up your body
i. Came from pre-existing cells
III. How did life begin?
a. A few centuries ago
i. People thought new living things appeared all of the time
ii. Spontaneous generation refuted
1. Mid 1800s- Louis Pasteur
a. Broth is boiled to kill preexisting microorganisms
b. Broth cools, condensing water sealing the flask at the
c. If the neck is broken off outside air can carry
microorganisms into broth
iii. Conditions on early earth
1. Atmosphere
a. CO2: CH4: NH3: H2: N2: HCl: H2S: H2O
i. Similar to Jupiter
b. No free oxygen
c. Frequent storms with lots of lightening
d. Frequent volcanic eruptions
e. Frequent meteor impacts
f. UV light from the sun
g. No ozone layer
iv. Earth before life arose
1. Earth is 4.6 billion years old
a. Radiometric dating of meteorites & moon rocks
2. Life arose about 3.8 billion years ago
a. Chemical traces in rocks 3.8 billion years
b. Fossil bacteria in rocks 3.5 billion years
c. No spontaneous generation now, but must have
happened then
3. The experiment of Miller & Urey (1952)
a. Chemical evolution
b. Water is required for life
i. And to catalyze reactions
c. Experiment
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i. Purified water
ii. Mix with gases of primeval atmosphere in the
spark chamber
iii. Are supposed to produce organic molecules few
days later
The experiment failed miserably, the water
was turned red with no life found
v. How to assemble a living thing
1. Accumulation of organic molecules
a. Nucleotides, amino acids, carbohydrates, and lipids
2. Catalyze reactions
a. Enzyme
i. Proteins
ii. Some RNA
3. Reproduce from stored genetic information
a. DNA
4. Separate the living thing from the outside environment
vi. The chicken or the egg?
1. Now: DNA --> RNA --> PROTEIN
a. Need proteins to synthesize DNA
vii. So how did the earliest cells do it?
1. Ribozymes
a. RNA molecules that can catalyze reactions,
especially those involved in synthesis and processing
RNA itself
i. Earliest cells used RNA to store information
ii. Ribozymes to catalyze reactions
2. Proto-cells
a. Just add fat and protein to water then shake
1. Water + elements + energy
2. Prebiotic Soup
a. Amino acids , nucleotides, lipids, sugars
3. Microsphere like protocells surrounding more complex
organic molecules like RNA, carbohydrates, proteins, and
4. First prokaryotes
ix. Family Tree of Life
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