LESSON 1d: EVOLUTION OF THE CELL Flashcards
Where did it all began?
The Big Bang Theory
- Interstellar dust and gases disturbed by a nearby
supernova - Gravity causes matter to coalesce into sun, planets,
moons, asteroids, comets, etc. - Formation requires more than 100 million years
The Big Bang
The Earth was likely formed roughly ___________ years ago
5,000,000,000
The age of earth according to science
4.6 billion years (an old earth)
The age of Earth according to Bible
6000 years (a young earth)
The History of Life: around 5 bya
Earth Created
The History of Life : more than 4 bya
crust cools
The History of Life: More than 3 bya
- Blue-green algae
- Oxygen released into atmosphere
The History of Life Now Runs Some
___ Billion Years
4.6
The History of Life : More or less 4 bya
First life
The History of Life: later than 1 bya nearly present
Cambrian explosion
The History of Life: In between 3 and 2 bya
Eukaryotic cells
The History of Life: less than 1 bya
Sponges, jellyfish, flatworms
evidence of the Big Bang
Microwave radiation
detected leftover, cooled down radiation
by carefully scanning the sky with a device
Arno Penzias and Robert Wilson
Arno Penzias and Robert Wilson detected leftover, cooled down radiation
by carefully scanning the sky with a device called the _______________. Their discovery was important evidence in support of the Big Bang
Theory and won them the Nobel prize in 1978
Holmdel Horn Antenna
The Environment for Life last 3.8 bya
- Volcanic Hot Springs
- Oceanic hydrothermal vent system
- Deep (below the level of UV penetration)
- Clays and/or Zeolites as templates
- Similarity with present day
chemosynthetic heterotrophic organisms
*Formed on November 1963
*Formed in a volcanic eruption
originating in the Mid-Atlantic Ridge
*A classic site for the study of bio-colonization of founder populations
BIRTH OF AN ISLAND
- Dark, billowing clouds of hot hydrothermal fluid are rich in
dissolved metals. - As they rise into the cool ocean water, they precipitate these
metals along the sides of the vent, thus creating a “chimney”
that builds over time.
Black smokers
Black smokers: The fluids also provide nutrients to a variety
of unusual plants and animals that
congregate around the vents in an area of
the ocean where life would generally _________
not exist
_________________ “sub-ice organic gazpacho” theory
(ice as a catalyst for abiosynthesis reactions)
Bada and Miller’s
Amino acids of extraterrestrial origin (2)
– Carbonaceous chondrite meteorites contain organic
compounds, amino acids,etc.
– Murchison Meteorite, Australia (L) and Allende Meteorite (~2
tons), Mexico (R)
The ______________ contained amino acids not occurring in chemical
systems of living things on earth (exotics). It has been hypothesized that life
originated out in space and came to earth inside a meteorite.
Allende Meteorite
The Murchison forms are interpreted to represent an indigenous population of the preserved and altered carbonized remains (microfossils) of microorganisms that lived in the parent body of this meteorite at diverse times during the past 4.5 billion years (Gy)
Richard B. Hoover
The ________________ are interpreted to represent an indigenous population of the preserved and altered carbonized remains (microfossils) of microorganisms that lived in the parent body of this meteorite at diverse times during the past 4.5 billion years (Gy)
Murchison forms
*Made of layers of sediments that contain
Precambrian fossils of bacteria and
Cyanobacteria
*About 3.5 million years old
*Layers reflect the presence of
communities of many types of microscopic
organisms
*Became mineralized and preserved in rock
layers
stromatolites
*Internal layering and close-up of___________ . Surface is covered by a felt of cyanobacterial filaments that trap sediment grains that are washed across the mat surface. Abundant sediment supply produces granular laminae, low sediment supply produces layers rich in organic matter (green in drawing).
columnar stromatolites
Age of Microbes
Precambrian
*The Precambrian was the age of microbes, macroscopically expressed in colonial
structures that we call ____________
stromatolite
*helped in the evolution of early multicellular animals by radically increasing
oxygen levels in lakes and lagoons
*microbial mats contained four times more
oxygen than the virtually lifeless water
above – sufficient to support early multi-cellular animals such as worms and larvae.
*Multi-cellular animals first evolved during
the Ediacaran period, around 635 to 542
million years back, when level of oxygen
were merely 10 per cent of today’s levels.
*Early mobile animals might have evolved in
such an environment, living in the biomats
and creating burrows similar to those found
in Ediacaran-aged rocks.
Bacterial mats
- Stages
– inorganic production of key simple organic molecules
– production of more complex molecules that can synthesize more of the same
molecule
– development of a genetic code of self-replicating molecules (RNA,DNA,proteins)
– production of the first cell by separation of these codes from the outer world by a
membrane - Aerobic vs. Anaerobic
– oxygen poisons living cells so early life was anaerobic - Lack of free Oxygen»_space; No Ozone layer
– UV radiation kills cells so life had to originate at depth;
– Water depths of 10m or more - Models
– non-oxidizing secondary atmosphere rich in the constituent chemicals for life–
H2O, CO2, N
– Energy in the form of UV radiation & Hot springs
Chemosynthesis
Stages of Chemosynthesis
– inorganic production of key simple organic molecules
– production of more complex molecules that can synthesize more of the same
molecule
– development of a genetic code of self-replicating molecules (RNA,DNA,proteins)
– production of the first cell by separation of these codes from the outer world by a
membrane
Oxygen poisons living cells so early life was _________
anaerobic
– UV radiation kills cells so life had to originate at depth;
– Water depths of 10m or more
Lack of free Oxygen»_space; No Ozone layer
models of chemosynthesis
– non-oxidizing secondary atmosphere rich in the constituent chemicals for life–
H2O, CO2, N
– Energy in the form of UV radiation & Hot spring
History of Origin of Life: 1828
Synthesis of Urea (Wohler)
History of Origin of Life: 1850
Synthesis of Alanine (Strecker)
History of Origin of Life: 1861
Synthesis of sugar (Butlerov)
History of Origin of Life: 1900
Synthesis of glycine (klages, Loo, Ling and Nanji)
History of Origin of Life: 1824-1929
Oparin, Haldane, Lipman, Harvey
History of Origin of Life: 1953
Miller Experiment
-Russian scientist (1930s)
-hypothesized that life
formed in the oceans
that formed on early
earth
Alexander Oparin
tested Oparin’s
hypothesis using electric
spark to substitute for
lightning
Stanley Miller and Harold Urey
(1953)
Production of hydrogen cyanide, formaldehyde and 4 different
amino acids from water vapor, methane, hydrogen and
ammonia and electrical sparks
Urey and Miller (1953)
- heated 18 different amino acids at 70oC to produce proteins( in water vapor,
CO2, and nitrogen and UV radiation) - demonstrated that short chain polypeptides could form abiotically from
amino acid monomers through dehydration of amino acid solutions - artificial proteins were also formed (protenoid microspheres)
spontaneously clumped together when brought into contact with water - resembled bacteria; lacked nucleic acids
- buds appeared when microspheres were allowed to stand in solution
- lipid-based microcells, called liposomes would form.
Sydney Fox (1959)
spherical shaped
proteins that are organized as a
membrane
Microspheres
collections of droplets of
different molecules, mainly amino
acids and sugars
Coacervates
In solutions of simple organic molecules, two structures form:
-Microspheres
-Coacervates
________ and ______formed protobionts, proteinoids, & microspheres (also called coacervate droplets)
Oparin and Fox
These molecular collections mimic cell behavior, but are non-living
Coacervate droplets
Coacervates properties of life?
- Accumulate monomers and polymers
from solution and grow - Divide (though only by budding off
portions of the ‘cell’) - Decompose glucose (one form of
metabolism) - Trap energy (a primitive form of
electron transport) - Have the potential for self-growth
(capable of some RNA and protein
synthesis) - Have the potential to undergo a kind of
selection
Biologist John Desmond Bernal coined the term __________ and suggested that there are a number of clearly defined “stages” in explaining the origin of life.
Biopoesis
Stages in explaining the origin of life?
- Stage 1: The origin of biological monomers
- Stage 2: The origin of biological polymers
- Stage 3: The evolution from molecules to cell
Who coined the term Biopoesis and suggested the stages in explaining the origin of life?
John Desmond Bernal
What did Bernal suggested about evolution?
-that evolution (natural selection) may have commenced early, some time between Stage 1 and 2
– Double membrane system
used in converting organic
molecules into energy
– Has plasmid DNA and
ribosomes
Mitochondria
– Double membrane system
used in converting energy
into organic molecules
– Has plasmid DNA and
ribosomes
Chloroplast
– Coral
* Zooxanthellae algae live
within tissues of coral polyp
(an animal)
– Bursaria
* Produced without singlecellular green algae
* Acquires through modified
ingestion, then incorporates
into its “body”
– Aphid gut bacteria study
* Bacteria species is losing its
genome, now just bigger than
that of a mitochondrion’s and
about as dependent on the
“host” organism
Modern Endosymbionts
Two endosymbiotic events c.2.7 bya
- prokaryotic host cell—>non-photosynthetic proto-eukaryotic cell
- Cyanobacterium–> photosynthetic eukaryotic cell
