TOPIC 1
(CHAPTER 1 and 18 in Mader’s
textbook)
A View of Life
Subtopic 1.1: How to Define Life
Subtopic 1.2: Evolution, The Unifying Concept of Biology
Subtopic 1.3: Origin of Life
Subtopic 1.4: History of Life
Subtopic 1.5: The process of Science
To describe the origin, nature, level of life
and endosymbiotic theory of the earliest
multicellular organisms
Subtopic 1.1: How To Define Life
• Biology is the scientific study of life.
• There is great diversity among living
things – in ocean and terrestrial
organisms
• Living things:
 are composed of the same
chemical elements as nonliving
things.
 obey the same physical and
chemical laws that govern
everything in the universe.
Diversity of Life
Despite diversity, all living things share the same basic
characteristics
Characteristics of Life
Adaptation
Reproduce &
develop
Organized
Materials and
energy
Respond
Homeostasis
Characteristics of Life: living things are organized
• The levels of biological organization
range from atoms to the biosphere.
• The cell is the basic unit of structure
and function of all living things.
 Unicellular or multicellular
• Each level of organization is more
complex than the level preceding it.
 As biological complexity
increases, each level acquires
new emergent properties.
Characteristics of Life: acquire material and energy
• Maintaining organization and carrying on
life requires an outside source of energy
(food, sunlight, chemicals)
• Energy is the ability to do work.
 Energy is required to maintain
organization and conduct lifesustaining processes such as chemical
reactions.
• The sun is the ultimate source of
energy for nearly all life on Earth.
 Photosynthetic organisms capture
solar energy and perform
photosynthesis.
 Photosynthesis - converts solar
energy into the chemical energy
of carbohydrates.
Characteristics of Life: maintain homeostasis
• Homeostasis is the maintenance of internal conditions within certain
boundaries.
 Ability to maintain a state of biological balance
 Feedback systems monitor internal conditions and make
adjustments.
Characteristics of Life: respond to stimuli
• Living things interact with the environment and respond to changes in
the environment
 Ability to respond often produce movement.
Characteristics of Life: reproduce and develop
• All living organisms must reproduce to maintain a population.
• manner of reproduction varies among different organisms.
• When organisms reproduce, they pass on copies of their genetic
information (genes) to the next generation.
 Genes determine the characteristics of an organism.
 Genes are composed of DNA (deoxyribonucleic acid).
Characteristics of Life: have adaptations
• Adaptation - modification that makes an organism better able to
function in a particular environment.
• diversity of life exists because over long
periods of time, organisms respond to
changing environments by developing
new adaptations.
• Evolution is the change in a population of organisms over time to
become more suited to the environment.
Subtopic 1.2: Evolution, The Unifying Concept of Biology
• The theory of evolution explains the diversity and unity of life.
 Theory suggests how all living things descended from a common
ancestor.
 Common descent with modification – enable organisms to be
adapted to their environment
Darwin’s Theory of Evolution by natural
selection is the principle of common
ancestry
All life earth can be traced back to a
single ancestor
• The ancestor is called last universal common ancestor (LUCA)
 common to all organisms that live and have lived since life began
• Life comes from life
 Molecules of living organisms called biomolecules
 First cells had to arise from nonliving chemicals, inorganic
substances
Natural Selection
• Evolutionary mechanism proposed by Charles Darwin
• Some aspect of environment selected which traits are more apt
to pass on to next generation
 Individual with favorable traits
produce the greater number
of offspring that survive and
reproduce
 Increase frequency of those
traits in population
• Mutation fuel natural selection – introduce variations members of a
population
Natural Selection
Natural Selection
Some plants within a population exhibit variation in leaf structure.
Deer prefer a diet of smooth leaves over hairy leaves. Plants with
hairy leaves reproduce more than other plants in the population.
Generations later, most plants within the population have hairy
leaves, as smooth leaves are selected against.
Evolutionary Tree of Life
An evolutionary tree is
like a family tree. An
evolutionary tree traces
the ancestry of life on
Earth to a common
ancestor.
NAI 2015
common
ancestor
(first cells)
BACTERIA
common
ancestor
(first cells)
ARCHAEA
BACTERIA
common
ancestor
(first cells)
ARCHAEA
cell with nucleus
EUKARYA
BACTERIA
common
ancestor
(first cells)
ARCHAEA
Protists
cell with nucleus
EUKARYA
BACTERIA
common
ancestor
(first cells)
ARCHAEA
Protists
cell with nucleus
Plants
EUKARYA
Fungi
Animals
BACTERIA
common
ancestor
(first cells)
ARCHAEA
Protists
Plants
cell with nucleus
EUKARYA
Fungi
Animals
Past
Time
Present
Organizing Diversity
• Because life is so diverse, it is helpful to group organisms into
categories
Taxonomy
Branch of biology that identifies,
names and classifies organisms
Systematics
Study of evolutionary
relationship between organisms
both extinct and modern
Organizing Diversity
Subtopic 1.3: Origin of Life
The Existence of Earth:
15 billion years ago
It started as a massive cloud of interstellar gases and cosmic
dust
Gravitational attraction condensed the vast cloud of
interstellar gases and cosmic dust into a gigantic spinning disc.
Big bang event was about 13.8 BYA (Billion Years Ago) is
considered as the age of universe with the formation of
subatomic particle and later become simple atom.
After the explosion, heavier elements formed the cores of the
planets, The Earth came into being about 4.6 BYA
The enormous heat of the earth’s interior produced massive
build up of hot gases, sparking violent volcanic eruptions that
thrust molten rock and gases out through the crust.
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The Earth’s mass provides a gravitational field strong enough
to hold an atmosphere. Early Earth’s atmosphere differed
from the current atmosphere, consisting of:
a. water vapor, (because too hot)
b. nitrogen,
c. carbon dioxide,
d. small amounts of hydrogen, methane (CH4), ammonia
(NH3), hydrogen sulfide (H2S), and carbon monoxide, no
oxygen.
As the Earth cooled, H2O vapor condensed to form liquid
H2O, and rain collected in oceans.
It was in the early ponds that life emerged through the
process of chemical evolution.
The molecules of the gases were ionizing by energy to form
C, H, N and O ions. C, H, N, O ions undergo interactions to
form organic monomer and organic polymer
(macromolecules) such amino acids, fatty acids,
hydrocarbons and nitrogenous bases compounds.
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Water vapor condensed into droplets that carried
nucleotides and amino acids to be in the primitive oceans
→ primordial soup
(organic soup) →
Bubbles/Protobionts/protocell →LIFE (see LUCA later)
Organic molecules formed on primitive earth: Where Life
Started. Life formed organisms.
Organisms develop and diversify through the process of
organic evolution which leads to 6 kingdoms of life.
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Stages of Origin of Life
Stage 1:
Evolution of Monomers
Stage 2:
Evolution of Polymers
Stage 3:
Evolution of protocells
Stage 4:
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Evolution of self replicating
system (living cells)
Stage 1: Evolution of Monomers
Primordial soup
Iron-sulfur
World
• Monomers came
from reactions in
ocean thermal vents
• Monomers came from
reactions in the
atmosphere
• Experiments performed
by Miller and Urey
(1953)
Extraterrestrial
Origin
• Monomers came
from outer space
Stage 1: Evolution of Monomer
• 3 hypotheses to explain how organic monomers could have
evolved.
1ST : PRIMORDIAL SOUP HYPOTHESIS AND THE MILLER-UREY EXPERIMENT
Primordial soup hypothesis – 1920’s by Oparin
(Russian) and Haldane (British)
 Propose that early earth had very little O2 and
made up of water vapor, H2, methane and
ammonia
 When these chemicals mixed, they contain elements C
and N, which can make amino acid
– the reaction activated by energy from solar
radiation, volcanic eruptions and lightning
 Ocean filled with many different organic molecules
like soup
Stage 1: Evolution of Monomer
• 3 hypotheses to explain how organic monomers could have
evolved.
1ST : PRIMORDIAL SOUP HYPOTHESIS AND THE MILLER-UREY EXPERIMENT
The Miller Urey Experiment
• Conducted an experiment to test the
Oparin/Haldane hypothesis.
 To show that simple organic molecules
could be made from inorganic
compounds
• The experiment trying to recreate the
conditions of pre-biotic earth:
 They succeeded in creating organic
molecules.
Miller and Urey Experiment
Miller-Urey Experiment
electrode
stopcock for
adding gases
electric
spark
CH4
NH3
H2
H 2O
stopcock for
withdrawing liquid
condenser
boiler
heat
gases
hot water out
cool water in
liquid droplets
small organic molecules
Stage 1: Evolution of Monomer
• 3 hypotheses to explain how organic monomers could have
evolved.
2ND : IRON SULPHUR HYPOTHESIS
• Wachtershauser (1980) proposed that
thermal vents at the bottom of the
earth ocean provide all the elements
and conditions necessary to synthesize
organic monomers
 known as iron-sulphur world
hypothesis
• Hypothesis states that:
 Dissolved gases emitted from thermal
vents such as CO, ammonia, hydrogen
sulphide
 Together with the action of catalyst
effects from iron and nickel would
produced organic molecules
Stage 1: Evolution of Monomer
• 3 hypotheses to explain how organic monomers could have
evolved.
3RD : EXTRATERESSTIAL ORIGINS
• Comet and meteorites perhaps carrying
organic chemicals, have pelted earth
throughout history
• The organic chemicals could have seeded
the chemical origins of life on early earth
• Bacterium like cells evolved first on another
planet and were carried to earth
 Meteorite on mars landed on earth some
13,000 y.a
 Tiny rod similar to fossilized bacteria was
found on the meteorite
Proof of life on mars??
Stage 2: Evolution of Polymers
• In cell, monomers join to form polymers in the presence of enzymes.
1ST : IRON SULPHUR WORLD HYPOTHESIS
• Have shown that organic molecules will react with amino acids to
form peptides in the presence of iron-nickels sulfides (found in
thermal vents)
2ND : PROTEIN-FIRST HYPOTHESIS
• Sydney Fox has shown that amino acids polymerize when exposed to
heat  proteinoids  micropsheres (composed of proteins but have
properties of cells)
Fox’s experiment showed that by heating some
proteins, proteinoids and microsphere form
spontaneously
Stage 2: Evolution of Polymers
3RD : RNA-first hypothesis
• Only the macromolecule RNA was needed at the beginning to
lead to the first cell.
• Thomas Cech and Sidney Altman (1980s) won Nobel Prize for their
discovery
Stage 3: Evolution of Protocells
Protocell: the 1st cell
on earth
Energy from the sun
and lightning strikes
molecules in the
sea
molecules combine
to form simple
organic molecules
Larger molecules
continue to form,
making simple
amino acids
Amino acids are the building blocks of life, Early protocells were
probably made of groups of amino acids
Stage 3: Evolution of Self Replication System
• RNA- first hypothesis suggest that RNA would first to evolve
 First true cells would have RNA genes
 These genes carried out enzymatic reaction of protein synthesis
• Protein-first hypothesis – proteins or at least poly peptides were the
fisrt to arise of three (DNA, RNA and protein)
 DNA came after proteins
1.4 : The History Of Life
The Geologic Timescale
• Geologists have divided geologic timescale into eras, periods and
epochs.
• It was derived from accumulation of data from the age of fossils.
• There are 4 eras, PPMC :
 Precambrian
 Paleozoic
 Mesozoic
 Cenozoic
Precambrian Time
• Life arose in the Precambrian Era
 The Precambrian encompasses 87% of the geologic time
scale.
 The first modern-type cells were prokaryotes (~3.5 BYA).
 Simple cells: do not have nucleus, membrane-bounded
organelles.
 Can live in the most inhospitable environments (hot springs, salty
lakes
 and oxygen-free swamps)
 Early bacteria probably resembled the archaea that live in hot
springs today.
 3.8 BYA, the first chemical fingerprints of complex cells occur; at
3.46 BYA, photosynthetic prokaryotic cells appear;
cyanobacteria.
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Precambrian Time: Eukaryotic Cells Arise
•
The endosymbiotic theory states that a nucleated cell engulfed
prokaryotes, which then became organelles.
•
Evidence includes:
 Present-day mitochondria and chloroplasts have a size that
lies within the range of that for bacteria.
 Mitochondria and chloroplasts have their own DNA and make
some of their own proteins.
 Mitochondria and chloroplasts divide by binary fission similar to
bacteria.
 The outer membrane of mitochondria and chloroplasts differ.
Precambrian Time: Eukaryotic Cells Arise
• Multicellular protists began to
appear
• Soft-bodied invertebrates
developed near the end of the
Precambrian
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The Tree of Life
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Paleozoic Era
Paleozoic Era
•
Lasted over 300 million years and was a very active period with three
major mass extinctions
• Cambrian Animals
 The Cambrian Period saw invertebrates flourish; invertebrates lack
a vertebral column.
Mesozoic Era
• Triassic Period
 Nonflowering seed plants became
dominant
• Jurassic Period
 Dinosaurs achieved enormous size
 Mammals remained small and insignificant
• Cretaceous Period
 Dinosaurs declined at the end of the
Cretaceous period due to a mass extinction
 Mammals: Began an adaptive radiation
Cenozoic Era
• Mammals and plants continued
adaptive radiation
• Primates evolution began
Mammals of the Oligocene Epoch
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Woolly Mammoth of the Pleistocene Epoch
1.5 : The Process Of Science
• The scientific method is a standard series of steps used in gaining
new knowledge through research.
• The scientific method can be divided into four steps:
Observation
Hypothesis
Experiments and Data Collection
Conclusion
THE END