evolution fyos lecture 4. c and h 2 o for alien life!
TRANSCRIPT
Evolution FYOSLecture 4
C and H2O for alien life!
CH2O
Common characteristics of Life
Biologists have identified at least six key features that appear to be shared by nearly all of living organisms on Earth.
o Order
o Reproduction
o Growth and Development
o Energy Utilization
o Response
o Evolutionary Adaptation
Characteristics of Life
Biologists have identified at least six key features that appear to be shared by nearly all of living organisms on Earth.
Order : all living organisms exhibit order in their internal structure.
molecules in living cells are not scattered randomly but instead arranged in specific patterns to make cell structures.
• Order
• Reproduction
• Growth and Development
• Energy Utilization
• Response
• Evolutionary Adaptation
Characteristics of Life
Biologists have identified at least six key features that appear to be shared by most or all of living organisms on Earth.
Order : all living organisms exhibit order in their internal structure.
However, snow flakes, for example, show remarkable structures also.
But, snow flakes are not alive!
• Order
• Reproduction
• Growth and Development
• Energy Utilization
• Response
• Evolutionary Adaptation
Characteristics of Life
Biologists have identified at least six key features that appear to be shared by most or all of living organisms on Earth.
Order : all living organisms exhibit order in their internal structure.
How about galaxies?
Are they alive?
Therefore, “order” is not sufficient condition for life. But, it is a necessary condition.
• Order
• Reproduction
• Growth and Development
• Energy Utilization
• Response
• Evolutionary Adaptation
Characteristics of Life
Reproduction: Organisms reproduce their own kind
A single-celled organism (an amoeba) copying its genetic material (DNA) and dividing into two
genetically identical cells.
Mule, Tigon, Liger, Computer virus?
Again, necessary condition, not sufficient!
• Order
• Reproduction
• Growth and Development
• Energy Utilization
• Response
• Evolutionary Adaptation
Characteristics of Life
• Growth and Development : Living organisms grow and develop in patterns determined at least by heredity
Growing embryos of Costa Rican frog
Heredity : passing on characteristics from one generation to next
Wild fires, crystal?
Again, necessary condition, not sufficient!
• Order
• Reproduction
• Growth and Development
• Energy Utilization
• Response
• Evolutionary Adaptation
Characteristics of Life
• Energy Utilization: Living organisms use energy to fuel their activities
Tube worms near a deep sea volcanic vent.
Car?
Again, necessary condition, not sufficient!
• Order
• Reproduction
• Growth and Development
• Energy Utilization
• Response
• Evolutionary Adaptation
Characteristics of Life
• Response: Living organisms actively responds to changes in its surroundings
A blacktail jackrabbit’s ears flush with blood, the blood automatically adjusted to maintain a constant internal temperature
Mercury in a thermometer?
Again, necessary condition, not sufficient!
• Order
• Reproduction
• Growth and Development
• Energy Utilization
• Response
• Evolutionary Adaptation
Characteristics of Life
• Evolutionary Adaptation: Life evolves in a way to become adapted to its surrounding
white-tail ptarmigan
Camo-moth
counter example?
• Order
• Reproduction
• Growth and Development
• Energy Utilization
• Response
• Evolutionary Adaptation
Evolutionary Adaptation
2 undeniable facts an inescapable conclusion
Heritable traits that enhance survival and reproduction will become progressively more
common in succeeding generations!
• Charles Darwin (1858)
An imaginary population of beetles of mixed color evolves into dark beetles.
DNA is the backbone of the Evolution!
Replicating the whole ~3 billion bases for human DNA takes only a few hours
About 1 wrong coupling in every ~1 billion bases!
Sickle-cell disease
• Just one base change in one gene (Adenine Thymine)
• Most mutations are harmful, but occasional good mutations are being picked up by “natural selection”
Mutation• About 1 replication error in billion chanceso wrong baseo deleted baseo extra base o etc.
• Most of these errors have no effectWhy? about 95% of human DNA bases are “non-
coding DNA”Most significant change is from “deleted base”.
• Due to this “error”, every individual living organism differ each other.
• Mutation = molecular engine of the evolutionary adaption!
• Any change in the base sequence of DNA
How did all these start in the beginning?
Organic Building Blocks
Miller-Urey ExperimentExperiment to create amino acids
(1953)
methane
hydrogen
water
ammonia
the first experiment to test the theory about the evolution of prebiotic chemicals and the origin of life on Earth.
How did the DNA world get started?
• Human DNA contains about 12 billion molecules• even a primitive virus has about 1 million molecules• many viruses use RNA instead of DNA as their genetic material
DNA from the start?
• Typical RNAs have 20-30 nucleotides…• Some RNAs are known to be self-replicable• RNAs are sufficiently simple so that several types of them could have been
created by “Miller-Urey”-type reactions.• These RNAs were exposed to the natural selection
Pre-cells
• Molecular evolution would have been much more efficient if RNA and other molecules are confined in a structure.o Increasing the rate of reactiono Isolating its content to facilitate natural selection among RNA molecules! If no such enclosure, enzyme created by the best RNA can help other RNAs.
Left: microscopic spheres made by cooling a warm solution of amino acidsRight : microscopic membranes made from lipids mixed with water (instantaneously formed!)
RNA cell?
Lipid pre-cell can form on the surface of clay!
+Very high chance of
making RNA on the surface of clay with membrane!!
• Right: lab experiment shows RNA strands (red) entrapped within a lipid pre-cell (green circle) made on the surface of clay!
Chemistry on the early Earth
6 Presentations on Feb 15
• Convergent evolutiono R. Shresthao J. Hedley
• Human Evolutiono E. Clendeningo A. Breeden
• Panspermiao Z. Rindiko C. Starlcup