part 2

What is the central overarching question explored in this EEMB 3 lecture?

How Has life on Earth Changed Over Time?

What basic pattern do groups of organisms exhibit through the fossil record over long periods?

Groups of organisms arise, diversify, and fall over time

Where are younger fossil specimens located relative to older ones within rock strata?

Younger specimens are found in younger stratum near the top; older specimens are in deeper, older stratum

What term describes a structural lineage on a phylogenetic tree that stops before reaching the present day?

A lineage ending in extinction

Name three large-scale macroevolutionary processes that cause major biological changes over time.

Continental drift, mass extinction, and adaptive radiation

Chemical and physical processes on early Earth could produce simple cells through how many distinct stages?

Four stages

What is the very first stage required for the prebiotic origin of simple living cells?

Abiotic synthesis of small organic molecules

What is the second stage required for the prebiotic origin of simple living cells?

The joining of small organic molecules into macromolecules

What is the third stage required for the prebiotic origin of simple living cells?

Packaging molecules into protocells

What is the fourth and final stage required for the prebiotic origin of simple living cells?

The origin of self-replicating molecules

What is the scientific definition of a prebiotic protocell?

Droplets with membranes that maintain an internal chemistry different from their surroundings

Approximately how many billion years ago (bya) did planet Earth originally form?

About 4.6 billion years ago

What destructive celestial events vaporized water and prevented early sea formation before 4 bya?

Collisions with massive rocks and ice

What vital gas was missing or present in very little quantities within Earth's early atmosphere?

Oxygen

What primary atmospheric components were heavily released by rampant ancient volcanic eruptions?

Water vapor plus various chemical compounds

Name six chemical compounds explicitly listed as constituents of the early volcanic atmosphere.

Nitrogen, nitrogen oxides, carbon dioxide, methane, ammonia, and hydrogen Hypotheses & Alternative Settings for Organic SynthesisWhich two scientists independently hypothesized that Earth's early atmosphere was a reducing environment?

During which decade did Oparin and Haldane independently propose their reducing atmosphere hypothesis?

The 1920s

What alternative atmospheric state do some modern geological evidences suggest instead of a reducing one?

The early atmosphere was neither reducing nor oxidizing

If the global atmosphere wasn't reducing, where localized might reducing conditions have formed first organic compounds?

Near the high-energy openings of volcanoes

What did the modern reanalysis of Stanley Miller's original 1953 experimental results demonstrate?

Amino acids formed readily under conditions simulating a volcanic eruption

What do comparative charts reveal about the 1953 results versus the 2008 reanalysis of Miller's experiments?

The 2008 reanalysis discovered a significantly higher number and total mass of synthesized amino acids

What deep-sea geological features are proposed as alternative sites for early organic molecule synthesis?

Deep-sea hydrothermal vents

What physical materials constantly gush out from beneath Earth's surface through hydrothermal vents?

Hot water and minerals

Why are "black smoker" hydrothermal vents considered poorly suited for the delicate origin of life?

Organic compounds are chemically unstable in the extreme heat (300-400°C) they release

What alternative category of vents releases warm water (40-90°C) with a high pH of 9-11?

Alkaline vents

Why would alkaline vents provide a much more suitable environment for the origin of life than black smokers?

Their warm temperatures and stable conditions do not instantly denature organic compounds

What extraterrestrial objects are proposed as a potential delivery source of organic molecules to early Earth?

Meteorites

What is the name of the famous 4.5-billion-year-old space rock that landed in Australia containing organic compounds?

The Murchison meteorite

Name four specific classes of organic compounds recovered from fragments of the Murchison meteorite.

Amino acids, lipids, simple sugars, and nitrogenous bases Macromolecules, Protocells, & Self-Replicating RNAHas spontaneous abiotic synthesis of all four fundamental RNA monomers been successfully demonstrated in labs?

How can primitive RNA polymers be induced to form spontaneously without any cellular enzymes?

By dripping a solution of RNA monomers onto hot sand, clay, or rock

What biochemical role could these early, spontaneously formed RNA polymers have filled on early Earth?

They could have acted as weak catalysts

What two definitive cellular properties of life may have originally appeared together inside protocells?

Replication and metabolism

From what fluid-filled microscopic structures might rudimentary protocells have originally constructed their walls?

Fluid-filled vesicles with a membrane-like structure

What specific mineral clay common on early Earth dramatically increases the structural rate of vesicle formation?

Montmorillonite

How does the presence of montmorillonite clay physically assist organic molecules to enter vesicles?

Organic molecules attached to montmorillonite can be absorbed directly through the vesicle membrane

What structural macromolecule was highly likely the very first genetic material on Earth?

RNA (not DNA)

What fundamental cellular process does RNA play a massive, central role in executing?

Protein synthesis

What special name is given to catalytic RNA molecules that function like protein enzymes?

Ribozymes

What specific chemical feat can ribozymes perform using loose, ambient nucleotide building blocks?

They can make complementary copies of short stretches of RNA

What major breakthrough did laboratory researchers recently construct regarding artificial protocells?

They built a vesicle inside of which the copying of a template strand of RNA could successfully occur

How did primitive protocells pass their internal catalytic RNA molecules on to "daughter" protocells?

They grew larger, split apart, and passed the RNA down mechanically

What evolutionary force began acting on protocells to select for more successful forms over generations?

Natural selection

What critical evolutionary template did structural RNA likely provide during the eventual origin of DNA?

A structural template for the direct assembly of DNA nucleotides The Fossil Record & Geological Dating MethodsWhat major information is fundamentally chronicled by the extensive Earth fossil record?

What are three primary observations made when viewing the fossil record as a whole?

Past organisms were unlike those today, many once-common groups are extinct, and new groups arose from existing ones

What type of physical fossil remnants include bones, shells, teeth, and raw plant material?

Preserved body parts

What type of fossils preserve ancient behavioral choices rather than body pieces?

Trace fossils (such as footprints and burrows)

What detailed ecological information is uncovered by studying the specific rock layer a fossil is trapped in?

Exactly when and where those ancient organisms lived

What are the individual, distinct accumulated sedimentary rock layers called?

Strata

Besides sedimentary rock, what highly unique amber-producing preservative traps pristine prehistoric insects?

Fossilized tree resin (amber)

Name two major evolutionary transitions explicitly documented by physical fossil evidence.

The rise of mammals and the direct evolution of modern birds from dinosaurs

Why is the fossil record an inherently incomplete, imperfect chronicle of biological evolution?

Few organisms preserved, many fossils were destroyed by geology, and only a fraction have been found

Name three specific structural or demographic biases that skew the known fossil record.

Biased in favor of species that existed a long time, were widespread/abundant, and possessed hard shells or skeletons

What are two major negative implications caused by fossil record bias?

An incomplete representation of past life and a distorted view of evolutionary patterns

How can fossil bias impact our modern calculations of ancient biodiversity?

It leads to highly misleading estimates of biodiversity and leaves gaps in transitional forms

Fossil record bias causes an unintended scientific overemphasis on what specific type of ancient environment?

Marine environments

What information is elucidated by analyzing the relative stacking order of fossils in rock strata?

The exact relative sequence in which those layers and organisms formed

Can relative dating of rock strata establish the actual, numerical age of a fossil?

No, it can only infer relative ages, not actual ages

What advanced laboratory technique is used to determine the absolute, actual ages of fossils?

Radiometric dating

Radiometric dating measures the precise, predictable decay of what chemical elements?

Radioactive isotopes

What is the definition of an isotope's radioactive "half-life"?

The exact time required for 50% of a parent isotope to decay into a daughter isotope

How do organisms acquire the specific chemical isotopes measured during radiometric dating?

They accumulate isotopes naturally from their surrounding environment while living

What specific isotope ratio is calculated to estimate the absolute age of a relatively young fossil?

The ratio of carbon-14 to carbon-12 isotopes

Why does the absolute mass of carbon-12 remain totally constant inside a fossil after an organism dies?

Carbon-12 is a stable isotope and does not undergo radioactive decay

Into what specific daughter element does radioactive carbon-14 slowly decay after an animal dies?

Nitrogen-14

What is the absolute maximum age limit for a fossil to be accurately dated using carbon isotopes?

Up to 75,000 years old

How do scientists date ancient fossils that are millions of years old if organisms don't use long-lived isotopes?

They date the radioisotopes with long half-lives found in surrounding layers of volcanic rock Origin of Mammals & The Geologic Time ScaleFrom what distinct ancestral group of terrestrial tetrapods did modern mammals gradually originate?

What structural changes are traced through the fossil record to chart the gradual evolution of mammals?

The step-by-step modification of mammalian jaws and specialized teeth

What type of basic dentition characterizes most non-mammalian tetrapods?

Undifferentiated, single-pointed teeth

What specialized term describes the mammalian condition of possessing multiple distinct tooth types?

Heterodont dentition

What is the primary mechanical function of mammalian incisors?

Incisors are used for tearing food

What is the primary mechanical function of mammalian canines?

Canines are used for piercing food

What is the primary mechanical function of mammalian pre-molars?

Pre-molars are used for shearing and crushing food

What is the primary mechanical function of mammalian molars?

Molars are used for grinding and processing food

What is the absolute largest primary division of geologic time on Earth?

An Eon

How many total geologic eons currently exist in the scientific timeline of Earth?

Only four eons

Name the four recognized geologic eons of Earth's history in chronological order.

Hadean, Archean, Proterozoic, and Phanerozoic

What subordinate time division is used to break down a large geologic eon into shorter segments?

An Era

Name the three distinct geologic eras that comprise the modern Phanerozoic Eon.

Paleozoic, Mesozoic, and Cenozoic

If Earth's entire history is condensed into a 1-hour countdown timer, how many minutes ago did animals originate?

About 9 minutes ago

If Earth's entire history is condensed into a 1-hour countdown timer, how long ago did humans appear?

Less than 0.2 seconds ago Key Milestones in the History of LifeWhat are stromatolites?

How many billion years ago do the oldest fossilized stromatolites date back to?

3.5 billion years ago

Why are fossilized stromatolites highly celebrated in the field of evolutionary biology?

They represent the earliest direct physical evidence of life on Earth

For approximately how long were simple prokaryotes the absolute sole inhabitants of planet Earth?

For more than 1.5 billion years

How many billion years ago do the oldest microfossils of single-celled eukaryotic organisms date back to?

1.8 billion years ago

What internal cellular innovation allows eukaryotic cells to dynamically change shape and engulf other cells?

A structural cytoskeleton

By what specific evolutionary process did complex eukaryotic cells originally acquire their internal mitochondria?

Endosymbiosis

What is the definition of an endosymbiont?

A small engulfed cell that lives entirely within a larger host cell

Do all modern eukaryotic cells contain mitochondria?

Yes, all eukaryotic cells have mitochondria

Do all modern eukaryotic cells contain plastids like chloroplasts?

No, only photosynthetic eukaryotes have plastids

What is the serial endosymbiosis hypothesis?

Mitochondria evolved before plastids through a sequence of distinct endosymbiotic events

What evolutionary milestone sparked the sudden development of immense morphological diversity?

The origin of eukaryotic cells and multicellularity

What is the scientific classification of the oldest known multicellular eukaryote fossil from 1.2 bya?

A small species of red algae

How many million years ago (mya) do large, diverse, soft-bodied multicellular organisms first appear in fossils?

Around 600 million years ago

What dramatic geologic event is characterized by the sudden appearance of many modern animal phyla?

The Cambrian Explosion

What is the exact, narrow multi-million-year window during which the Cambrian Explosion occurred?

535–525 million years ago

Fossils of which three simple animal groups appear in older rocks dating before the Cambrian Explosion?

Sponges, cnidarians, and mollusks

What ecological behavior shows almost zero physical evidence in fossils prior to the Cambrian Explosion?

Predation

What specialized hunting adaptations rapidly appeared in predators within 10 million years of the explosion?

Large body sizes and sharp claws

What defensive structural innovations arose in prey species to counter Cambrian predators?

Sharp spines and heavy body armor Land Colonization, Plate Tectonics, & Mass ExtinctionHow many billion years ago did simple prokaryotes first successfully transition to living on land?

How many million years ago did macroscopic fungi, plants, and animals begin to colonize land?

About 500 million years ago