3 The Origin and Evolution of Life on Earth

Evolution

Change in populations over generations.

Descent with Modification

Process of evolution through inherited traits.

Miller-Urey Experiment

Demonstrated organic molecule formation from inorganic compounds.

RNA World Hypothesis

Early life based on RNA molecules.

DNA World

Transition from RNA-based life to DNA-based life.

Prokaryotic World

Dominance of single-celled organisms without nuclei.

Endosymbiotic Theory

Eukaryotic cells evolved from symbiotic prokaryotes.

Horizontal Gene Transfer

Transfer of genes between organisms, not parent to offspring.

Absolute Dating

Determining the exact age of fossils.

Relative Dating

Determining the age of fossils based on layers.

Pangea

Supercontinent that existed 200 million years ago.

Earth's Climate Change

Gradual cooling with occasional extreme temperature drops.

Early Earth Conditions

Little free oxygen and acidic water present.

Organic Molecules

Building blocks of life formed in early Earth.

Cell Theory

Cells are the fundamental units of life.

Oxygen Production

Began approximately 2.7 billion years ago.

Eukaryotes

Organisms with complex cells, emerged 2.5 billion years ago.

Multicellularity

Development of organisms composed of multiple cells.

Fossil Age Calculation

Methods to determine when life forms existed.

Life Origin Timeframe

Life began around 3.5 billion years ago.

Vertebrates

Animals with backbones, appeared 0.52 billion years ago.

Humans

Modern humans emerged approximately 195,000 years ago.

Organic Molecules

Compounds containing carbon, essential for life.

Inorganic Reactants

Non-carbon-based substances used in chemical reactions.

Artificial Synthesis

Creation of organic compounds from inorganic materials.

Friedrich Wöhler

German chemist who synthesized urea in 1828.

Miller-Urey Experiment

1952 experiment demonstrating spontaneous organic molecule formation.

Protocells

Early cell-like structures trapping organic molecules.

Cell Membranes

Structures surrounding cells, composed of lipids and proteins.

Hydrophilic Components

Molecules that are attracted to water.

Hydrophobic Components

Molecules that repel water.

Central Dogma

Information flow: DNA to RNA to protein.

RNA World Hypothesis

Theory that early life was based on RNA.

Transcription

Process of copying DNA into RNA.

Translation

Process of synthesizing proteins from RNA.

Chemical Selection

Natural selection of molecules based on replication efficiency.

tRNA

Transfer RNA, links amino acids during protein synthesis.

mRNA

Messenger RNA, carries genetic information from DNA.

rRNA

Ribosomal RNA, component of ribosomes for protein synthesis.

Enzymatic Activity

Catalytic function of proteins or RNA.

Deep Sea Vents

Locations where organic molecules were discovered forming.

Spontaneous Origin

Natural formation of organic molecules without biological intervention.

Amino Acids

Building blocks of proteins, formed in experiments.

RNA Monomers

Single units that link to form RNA polymers.

Metabolism

Biochemical processes for energy and molecular synthesis.

Mutations

Changes in DNA leading to protein diversity.

Protocells

Primitive cell-like structures with functional proteins.

Membranes

Structures that encapsulate and protect cellular contents.

Organic Molecules

Carbon-based compounds essential for life.

RNA World

Hypothetical early stage of life based on RNA.

Chemical Selection

Process favoring molecules with advantageous properties.

DNA and Proteins Relationship

Interdependence of genetic information and functional proteins.

Formation of Organic Molecules

Initial step in the origin of life.

Formation of Membranes

Creation of barriers for cellular organization.

RNA to DNA Transition

Evolutionary shift from RNA-based to DNA-based life.

Initiation of Metabolic Pathways

Beginning of biochemical reactions for energy production.

Diversification of Life

Evolutionary process leading to varied life forms.

Novel Proteins

Unique proteins resulting from genetic mutations.

Catalyze Production

Accelerate chemical reactions to form new molecules.

Light Absorption

Process altering molecular structure and function.

Last Universal Common Ancestor

Earliest organism from which all life evolved.

RNA World

Hypothesis that RNA was the first genetic material.

DNA World

Transition from RNA to DNA as genetic material.

Metabolism

Chemical processes that occur within living organisms.

Prokaryotic Cell

Unicellular organism lacking a nucleus.

LUCA

Last Universal Common Ancestor of all life.

Bacteria

Single-celled prokaryotic microorganisms.

Archaea

Prokaryotic organisms distinct from bacteria.

Eukarya

Domain of life with complex cells.

Stromatolites

Layered structures formed by prokaryotic fossils.

Oxygenic Photosynthesis

Process producing oxygen from light energy.

Chemoautotrophs

Organisms obtaining energy from chemical reactions.

Aerobic Cellular Respiration

Metabolic process using oxygen to produce energy.

Endosymbiotic Theory

Mitochondria and chloroplasts originated from prokaryotes.

Mitochondria

Organelles responsible for energy production in eukaryotes.

Chloroplasts

Organelles for photosynthesis in plant cells.

Binary Fission

Asexual reproduction method in prokaryotes.

Banded Iron Formation

Sedimentary rocks indicating ancient oxygen production.

Prokaryotic World

Era dominated by prokaryotic life forms.

Multicellularity

Organisms composed of multiple cells.

Eukaryotic Cells

Cells with membrane-bound organelles and nucleus.

First Life

Prokaryotes emerged approximately 3.5 billion years ago.

24-Hour Analogy

Conceptual timeline illustrating Earth's history.

Multicellularity

Evolved 1.2 billion years ago, enabling specialization.

Cell adhesion molecules

Facilitate attachment between daughter cells.

Extracellular matrix

Supports cell structure and communication.

Chlamydomonas reinhardtii

Unicellular alga, model organism for studies.

Gonium pectorale

Composed of 8 identical cells.

Homo sapiens

Species with 50-75 trillion cells.

Pleodorina californica

64-28 cells; includes somatic and reproductive types.

Volvox aureux

1000-2000 cells; has somatic and reproductive types.

Relative dating

Ordering fossils by age without exact dates.

Absolute dating

Assigning specific dates to fossil ages.

Fossil record

Used to determine historical biological events.

Isotope

Variant of an element with different neutron counts.

Radiometric dating

Determines age using radioactive isotope decay.

Half-life

Time taken for half of a substance to decay.

Parent isotope

Original radioactive isotope before decay.

Daughter isotope

Product of decay from parent isotope.

K40

Potassium-40, decays to Argon-40.