2. Important Molecules of Life DNA Stores genetic material RNA Protein synthesis and other important roles Proteins Structure and activity of the cell
3. How they came to be . . . The origin of life occurred in four stages Stage 1 – Organic molecules were produced before cells existed Stage 2 – Polymerization of organic molecules formed polymers Stage 3 – Polymers became enclosed in membranes Stage 4 – Membrane bound polymers acquired cellular properties
4. Stage 1 Nucleotides and amino acids were created before the existence of cells It is hypothesized that these organic molecules formed spontaneously due to the conditions of early Earth The molecules formed a prebiotic soup
5. Reducing Atmosphere Hypothesis Early Earth had a reducing atmosphere Lacked oxygen Abundance in water vapor, hydrogen gas, methane, and ammonia Miller and Urey experiment
7. Deep-Sea Vent Hypothesis Cracks in the Earth’s surface releases hot water The mixture of the hot water and the cold sea water created a gradient suitable for the formation of organic molecules
8. Stage 2 Nucleotides and amino acids were polymerized to form RNA/DNA and proteins Polymerization took place on clay Could not take place in water because hydrolysis would compete with polymerization Clay can catalyze reactions
9. Stage 3 Droplets of organic material Surrounded by a ring of water molecules Vesicles with a phospholipid membrane Coacervate Liposome
10. Stage 4 Polymers underwent mutations that changed their function Chemical Selection Polymers that had functions that were beneficial, were increased
11. RNA World It is hypothesized that the world used to be an RNA world RNA’s Key functions Information storage Enzymatic activities Self-replication RNA underwent mutations New functions
12. RNA DNA/RNA/Protein Information Storage DNA took up RNA’s ability to store information Reduced the roles of RNA DNA was created through reverse transcription Cellular Functions Proteins took up the function of catalyst and others Proteins were formed due to RNA’s ability to catalyze the formation of peptide binds
Hinweis der Redaktion
Required for living
Disagreements on how and when they originated leads to next slides
Explain boundary. What it is and was for.Both boundaries are selective
Maria will explain whether or not RNA world is possible