23 terms

Quiz 1: The History of Life on Earth


Terms in this set (...)

Natural Selection

Artificial Selection
Survival of the fittest: capability to leave behind offspring is what classifies if an organism is fit.

Interaction between animals and the environment is what allows natural selection to occur.

The environment is a filter to allow fittest to leave behind offspring and one's without capability to die out (traits disappear from populations

Artificial Selection: Dog Breeding
Key Concepts/Events
Biological Hierarchy and Nomenclature

1. The origins of the single celled prokaryotes (pattern) and the chemistry of early earth (process)
2. the origins of eukaryotes (pattern) and how they evolved (natural selection) and the oxygen revolution (process)
3. Multicellularity and increased body size and complexity (pattern) and the evolution of predator-prey interactions (process)
4.The colonization of land (pattern) and the evolution of characteristics that enhance water retention (process)
plants and fungi-pattern
evolution that increased water retention for all
Domain: 3: bacteria, archaea(both prokaryotes, before nucleus), eukarya(w/nucleus)
Kingdom: in bacteria and archaea(unknown, microscopic) in eukarya: plantae, animalia, fungi, protista

Nomenclature and founder
All organisms are referred to by their genus and species ex: Homo sapiens
1st Genus (capitalized) 2nd Species (uncapitalized), italics typed, underlined written
Founder: Carolus Linneaus: classified organisms and gave binomial nomeclature
What is a Prokaryote?
The original evolution of life or living organisms from inorganic or inanimate substances.
Conditions on early earth made the origin of life (prokaryote) possible
Pro: before Karyon: nucleus: single celled organism w/o nucleus
Steps in the creation of life from non-life

how to know if something is living
Chemical and physical processes on early Earth may have
produced very simple cells through a sequence of stages:
1. Abiotic synthesis of small organic molecules
2. Joining of these small molecules into macromolecules (polymers)
3. Packaging of molecules into "protobionts" (pre-living thing)
4. Origin of self-replicating molecules

monomers chain together (proteins: amino acids, genes: nucleotides) and form polymers

If something metabolizes or reproduces, then it is living.
Abiotic Synthesis of small organic molecules
Earth formed about 4.6 billion years ago
• Oparin and Haldane hypothesis
- Early Earth had a reducing (redox reactions, now is an oxidizing atmosphere) atmosphere and oceans with water
vapor and chemicals released by volcanic eruptions (N, H, CO2
methane, ammonia, hydrogen sulfide)
• What is missing? OXYGEN: wasn't free oxygen, bound in other molecules
• Miller and Urey experiments
- Tested the Oparin-Haldane hypothesis: added an energy source
(electricity:mimics lightening) and found that it was possible to make amino acids,
nucleotides and other small organic molecules
heat, uv radiation, electricity caused small organic molecules to form from inorganic matter
Abiotic Synthesis of Macromolecules
• Small organic molecules polymerize (takes energy) spontaneously when
they are concentrated on hot sand, clay, or rock
- The presence of zinc creates longer polymers
• Some of these polymers could then have acted as
catalysts for other biological reactions**
Packaging of molecules into protobionts
• Protobionts are cell-like structures that exhibit simple
reproduction and metabolism and maintain an internal
chemical environment
• Experiments demonstrate that protobionts could have
formed abiotically
- For example, small membrane-bounded droplets called
liposomes can form when lipids or other organic molecules are
added to water (capable of simple forms of metabolizing and reproduction)
(you can make monomers, polymers, probonts, liposomes in a lab
Liposomes are capable of simple reproduction and, if certain enzymes
(phosphatase and amylase) are added, simple metabolic reactions.
Self- Replicating molecules: RNA
RNA molecules called ribozymes have been found to
catalyze many different reactions
- Ribozymes (catalyze different reactions) can make complementary copies of short stretches of
their own sequence or other short pieces of RNA
- A protobiont with ribozymes could grow, split, and pass RNA to its
• In early 2009 Canadian researchers identified a way that
ribosomes could self-assemble via basic chemical
Life from non-life
Has anyone ever created life synthetically?
Craig Venter
Has anyone ever created life synthetically?
• In 2010, Craig Venter claimed to have created the world's first synthetic life form. What did he do?
took synthetic genome for prokaryote and put it in living prokaryote, it worked, made a functioning synthetic genome
The first single celled organisms
The oldest known fossils are from stromatolites (fossil prokaryotes, sedimentary rock structures), rock-like structures composed of layers of bacteria and sediment
- Prokaryote cells found in stromatolites date to 3.5 billion
years ago
- Life on Earth could not begin until the planet cooled enough
for liquid water
- Prokaryotes were Earth's sole inhabitants from 3.5 to about
2.1 billion years ago (bya)
also carbon in rock tht appears to be laid down by photosynthetic organisms
Ecosystem Services
Things other organisms do in nature that benefits humans
ex: photosynthesis
ex: cycling of nutrients
ex: decomposition(recycling)
Photosynthesis and the Oxygen Revolution
Most atmospheric oxygen (O2) is of biological origin,
produced by photosynthesis
• About 2.7 bya, O2 began accumulating in the atmosphere;
this was the "oxygen revolution" from 2.7 to 2.2 bya
- Many prokaryotes perished
- Some survived in anaerobic environments
- Others adapted and exploited new ecosystems: eukaryotes (rise of eukaryotes is correlated to rise of oxygen)
Facultative Relationship vs. Obligate R.
One organism eats another to live aerobically, can do it but not obligate

Have to have it, eukaryotic cell needed to have mitochondria
The first eukaryotes
The oldest eukaryotic fossils date to 2.1 bya
- What is a eukaryote? (Eu = "with", Karyon = "nucleus")
• Endosymbiosis proposes that mitochondria and
chloroplasts were formerly small prokaryotes living within larger host cells (ex: mitochondria coes from protobacteria, chloroplasts, cyanobacteria***)
- An endosymbiont is a cell that lives within a host cell
- The ancestors of mitochondria and plastids probably entered host
cells as undigested prey or internal parasites
- As they became interdependent, the host
key evidence supporting an endosymbiotic origin of mitochondria and plastids:
- Similarities in inner membrane structures and functions
- Division is similar in these organelles and some prokaryotes
- These organelles transcribe and translate their own DNA
- Their ribosomes are more similar to prokaryotic than eukaryotic
The Origin of Multicellularity
Based on DNA evidence, multi-cellularity evolved about
1.5 bya
- These "protists" gave rise to algae, and eventually to fungi, plants,
and animals
- Multicellular organisms remained small until about 565 mya - the
larger (up to 1m long), soft-bodied, organisms appearing at this
time are known as the "Ediacaran fauna"
Why be multicellular?
• Increased size
- Bigger predators can eat a larger range of food; bigger prey can
be eaten by fewer organisms
• Division of labor
- Cells can become specialized, and more efficient: may provide a
competitive edge
• Longer lives (replace cells)
- Life span of organism is not limited to the life span of a particular
- Longer lifespan means more time for reproduction
The Colonization of Land
• Cyanobacteria probably coated damp terrestrial surfaces
over 1 bya but true colonization of land occurred within the
last 500 mya
- Plants and fungi likely colonized land together by 420 million
years ago
- Arthropods colonized land about 419 mya
- Tetrapods evolved from lobe-finned fishes around 365 mya
• Arthropods and tetrapods are the most widespread and diverse land
Carbonaceous Condrites
Meteorites from space that have amino acids in them
Oldest of Earth:
Hadean Eon: too hot for anything living.