UNIT 3: EVOLUTION
EVOLUTION
1. ORIGIN OF LIFE
Abiogenesis: the process by which life arises spontaneously from non-living matter.
Primordial soup hypothesis
- Early earth had a chemically active atmosphere.
- This atmosphere, exposed to energy in various forms, produced simply organic
compounds.
- These compounds accumulated in a “soup” which may have concentrated at
various locations*.
- By further transformations, more complex compounds and eventually life
developed in the “soup”.
Miller-urey experiment
- Designed an apparatus which held a mixture of gases (hydrogen, methane,
nitrogen, ammonia, sulfur) similar to those found in Earth’s early atmosphere
over a pool of water, representing the ocean.
- It was heated over a burner to simulate heat from the sun.
- Electrodes delivered electric current, simulating lightning.
- After one week, they found that several amino acids had formed spontaneously
from inorganic raw materials.
- Assumed the conditions of early earth.
Hydrothermal Vents
- A fissure in the planet’s surface from which heated water issues.
- Commonly found near volcanically active places, and where tectonic plates are
moving apart.
- Chemosynthesis: using chemicals, instead of sunlight, as a source of energy for
producing food (an alternative to photosynthesis.)
Panspermia theory
- Hypothesis: that life exists throughout the universe, and is distributed by
meteorites, asteroids, and comets.
- Some microscopic life forms (extremophiles) can survive the effects of space.
- They can travel dormant for extended amounts of time before colliding randomly
with planets.
- If met with ideal conditions, they can become active and the process of evolution
begins.
- Does NOT address how life began.
, UNIT 3: EVOLUTION
Organic molecules in space
- A meteorite from Mars contained organic compounds that could be the remains
of bacteria.
- Microbes survive on outside of International Space Station.
- Microbes millions of years old from Antarctic ice.
Great oxygenation event
- Oxygen first appeared 2.45 billion years ago
- Cyanobacteria were the first microbes to produce oxygen as a byproduct of
photosynthesis, and forever changed Earth’s atmosphere.
The formula for
photosynthesis:
- Increased oxygen concentrations provided a new opportunity for biological
diversity and life as we know it.
Prokaryotes:
- A simplest single-celled organism that lacks a nucleus or other organelles with
membranes.
- The first living organisms from which all other forms of life evolved.
- Sometimes bacteria were absorbed by other bacteria, forming more complex
bacteria with organelles.
- Large mats of these organisms sometimes “stuck” together and began to
cooperate: this may be how complex organisms formed (experimental evidence
exists for the mats of bacteria)
2. CHARLES DARWIN
Father of evolutionary theory: Charles Darwin (1808-1882) English naturalist and
geologist.
- Developed the theory of natural selection
- On the Origin of Species
- Contradicted established scientific knowledge of the time
- Contradicted religious beliefs
- Connected observations of the natural world (Galapagos finches), population
studies, geologic time theories, and selective breeding
- Co-published with Wallace after withholding his ideas for years
Observations of the natural world:
- Different body characteristics seemed related to the environment
EVOLUTION
1. ORIGIN OF LIFE
Abiogenesis: the process by which life arises spontaneously from non-living matter.
Primordial soup hypothesis
- Early earth had a chemically active atmosphere.
- This atmosphere, exposed to energy in various forms, produced simply organic
compounds.
- These compounds accumulated in a “soup” which may have concentrated at
various locations*.
- By further transformations, more complex compounds and eventually life
developed in the “soup”.
Miller-urey experiment
- Designed an apparatus which held a mixture of gases (hydrogen, methane,
nitrogen, ammonia, sulfur) similar to those found in Earth’s early atmosphere
over a pool of water, representing the ocean.
- It was heated over a burner to simulate heat from the sun.
- Electrodes delivered electric current, simulating lightning.
- After one week, they found that several amino acids had formed spontaneously
from inorganic raw materials.
- Assumed the conditions of early earth.
Hydrothermal Vents
- A fissure in the planet’s surface from which heated water issues.
- Commonly found near volcanically active places, and where tectonic plates are
moving apart.
- Chemosynthesis: using chemicals, instead of sunlight, as a source of energy for
producing food (an alternative to photosynthesis.)
Panspermia theory
- Hypothesis: that life exists throughout the universe, and is distributed by
meteorites, asteroids, and comets.
- Some microscopic life forms (extremophiles) can survive the effects of space.
- They can travel dormant for extended amounts of time before colliding randomly
with planets.
- If met with ideal conditions, they can become active and the process of evolution
begins.
- Does NOT address how life began.
, UNIT 3: EVOLUTION
Organic molecules in space
- A meteorite from Mars contained organic compounds that could be the remains
of bacteria.
- Microbes survive on outside of International Space Station.
- Microbes millions of years old from Antarctic ice.
Great oxygenation event
- Oxygen first appeared 2.45 billion years ago
- Cyanobacteria were the first microbes to produce oxygen as a byproduct of
photosynthesis, and forever changed Earth’s atmosphere.
The formula for
photosynthesis:
- Increased oxygen concentrations provided a new opportunity for biological
diversity and life as we know it.
Prokaryotes:
- A simplest single-celled organism that lacks a nucleus or other organelles with
membranes.
- The first living organisms from which all other forms of life evolved.
- Sometimes bacteria were absorbed by other bacteria, forming more complex
bacteria with organelles.
- Large mats of these organisms sometimes “stuck” together and began to
cooperate: this may be how complex organisms formed (experimental evidence
exists for the mats of bacteria)
2. CHARLES DARWIN
Father of evolutionary theory: Charles Darwin (1808-1882) English naturalist and
geologist.
- Developed the theory of natural selection
- On the Origin of Species
- Contradicted established scientific knowledge of the time
- Contradicted religious beliefs
- Connected observations of the natural world (Galapagos finches), population
studies, geologic time theories, and selective breeding
- Co-published with Wallace after withholding his ideas for years
Observations of the natural world:
- Different body characteristics seemed related to the environment
