Evolution Flashcards
Module 1 (Lecture 2)
When did Earth form?
Approximately 4.6 billion years ago
What di early Earth Lack?
It lacked atmosphere, soil and oceans
Which Hypothesis explains the beginning of life on earth?
Oparin-Haldane Hypothesis
Who came up with the Oparin-Haldane Hypothesis? and when?
Alexander Oparin and J.B.S. Haldane
(1920s)
The Oparin-Haldane Hypothesis is also known as the…
“Primordial soup theory”
What does the Oparin-Haldane Hypothesis entail?
Compounds characteristic of life formed slowly over time from simple molecules present in the prebiotic environment
What is the “Equation” for the Primordial Soup Theory?
Simple Compounds
+
An energy source
=
More complex organic molecules
What were the Simple Compounds of the Promordial Soup Theory?
Water vapor, Carbon dioxide, Hydrogen gas, Methane, Ammonia, Limited free oxygen
What crucial simple compound was limitied in the early earth?
Oxygen
What were the possible energy sources of the Promordial Soup Theory?
Lightening, UV light, Energy from volcanoes
Was the Oparin-Haldane Hypothesis ever tested or even testable?
Yes
What experiment prooved the Oparin-Haldane Hypothesis?
The Miller-Urey Experiment (1953)
What experiment does this image represent?
The Miller-Urey Experiment (1953)
Who conducted the Miller-Urey Experiment and when?
Stanley Miller and Harold Urey (1953)
What was the procedure for the Miller-Urey Experiment?
Circulated a mixture of; water, hydrogen, methane and
ammonia with an Energy source; electrical spark
What was the result of the Miller-Urey Experiment?
In a week, 15% of the
carbon in the mixture was converted to ‘organic’ compounds such as: amino acids, urea, fatty acids
What was the next stage after the formation of organic compounds?
Formation of polymers
e.g. proteins, nucleic acids
Where did Polymers probably form? And why?
Within semipermeable amphiphilic membranes
Semipermeable membranes provide protection in aqueous solution where polymers would tend to be hydrolysed
Amphiphilic
one part soluble in water (polar), another part insoluble in water (non-polar)
Place The following in order:
1. Packaging of macromolecules into membranes to form protocells
2. Simple inorganic molecules formed and began to accumulate in the early oceans
3. Origin of self-replicating molecules and true cells
4. Formation of macromolecules (e.g. proteins, nucleic acids)
5.Abiotic synthesis of small organic molecules
2, 5, 4, 1, 3
Could life on earth start again? And Why?
Probably not
Early atmosphere was strongly reducing (lacked oxygen gas).
These conditions were conducive to prebiotic synthesis of life.
Present atmosphere is strongly oxidizing.
Molecules necessary for life can’t be synthesized outside of cells (unstable in the presence of oxygen).
What is this type of evolution?
Formation of complex organic molecules from simpler inorganic
molecules through chemical reactions (abiotic). First step in the development of life on this planet.
Chemical Evolution
What is this type of evolution?
The process by which changes in the genetic composition of populations of organisms occur in response to environmental changes. Descent with modification
Organic Evolution
Why is it essential to view Biology in an evolutionary perspective?
Without evolution Biology is meaningless/ missing the big picture.
