objectives: be able to summarize the miller-urey experiment
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Objectives:
1.Be able to Summarize the Miller-Urey Experiment2.Relate the structure of Clay beds to the polymerization of nucleotides3.Understand the role of meteorite impacts in polymerization of Proteins4.Relate the structure of phospho-lipids to the formation of cell membranes.
Two Characteristics of a Living Thing
Must be able to store information (RNA or DNA)
Express that information (proteins)
Keratin: A hard durable protein found in Hair and Nails/Claws
Proteases: Protiens that help digest proteins (meat)
Actin /Mysosin: Proteins that are used in muscle fibers.
Collagen: Found in connective tissue
PSD-95: Protein that builds connections between synapses
What came firstThe protein that makes up our body, or the
RNA/DNA that codes for the protein?
Conditions of the Early Earth
• Little oxygen in the atmosphere: Atmosphere is composed of CN, NH4, CH4, H2
• Violent electrical storms• Heavy Bombardment: A time when the earth
is constantly hit with meteorites.
Miller-Urey Experiment
• Adds early atmospheric gases to a flask connected to another flask with water (simulating the early oceans).
• Shot electrodes (simulate lightning) through the gases.
• Produced amino acids (building blocks of Proteins) from the gases.
The Murchinson Meteorite
• In 1969 a meorite hit earth in Australia• The meteorite was covered in thousands of
amino acids, the building block of proteins.• Panspermian hypothesis: that life actually
originated in space and was brought to this planet.
Experiments with Amino Acids under large impact pressures
• Scientist hypothesized that if amino acids were placed under meteorite impact pressure, then they would vaporize.
• The hypothesis was proved wrong: Amino acids Polymerized into long chains of protein.
Dr. Jennifer Blank
The Formation of Nucleotides
• Each of the 4 Nucleotides found in DNA: Adenine, Thymine, Cytosine, and Guanine have been synthesized in the laboratory using early atmospheric gases and an electrical discharge.
Polymerization of Nucleotidesinto Nucleic Acids
• Polymerization: to attach smaller building blocks into long chains
Clay beds may have polymerized Nucleotides into long chains
A T C G A C G
Evidence for Clay Beds
• Many Organic Molecules are Chiral (mirror images), and come in two different isomers, either left-handed and right handed.
• Clay beds only polymerize the L-isomer of nucleotides.
• The L-isomer is the only form that nucleotides are found in living organisms.
Ribozymes
• Ribozyme: A sequence of RNA (nucleic acid) that can catalyze chemical reaction.
• It can act as both a heritary molecule (store information) and performs a function (expresses that information).
• Biologist have discovered a Ribozyme that can catalyze its own synthesis.
• Some of these Ribozymes would have been enclosed and protected in a lipid by-layer, creating the first living cell.
Natural Selection on the Molecular Level
• Once the first molecule of RNA began to self-replicate Natural Selection can go to work.
• Sequences that were more efficient at self-replicating increased in population.
• Walter Gilbert proposed that the cell used RNA as both the genetic material and the catalytic molecule, rather than dividing these functions between DNA and protein as they are today.
• This hypothesis became known as the " RNA world hypothesis” of the origin of life.
Essay Question on the Exam
You meet a man named bob who notices you studying your biology Cornell notes. “Oh” say Bob, “ I’ve always wondered how life came to be covering our planet.”
Explain to Bob the RNA world hypothesis.
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