This ppt introduces the basic properties of life and the different theories about the origin of life.

1. The Properties and Origin of Life
Reymon T. Dela Cruz November 2, 2022

2. Reymon T. Dela Cruz November 2, 2022
Properties of Life
Organization
Biological systems are extremely
organized. At the chemical level, atoms
are organized into biomolecules which in
turn comprise cellular organelles.
Organelles function interrelatedly and
give rise to cells, the basic unit of life. In
complex multicellular organisms, cells
are organized into tissues, tissues form
different organs and organs are
components of organ systems which
comprise an organism.
Biological organization goes well beyond
the organismal level. Organisms of the
same species make up a population, a
collection of population of different
species form a community, biological
communities together with the abiotic
components of the environment forms an
ecosystem and the collection of all
ecosystem forms our planet’s biosphere.

3. Reymon T. Dela Cruz
A B
b
C
G
E
D
November 2, 2022
Phospholipid (A) molecules in combination
with proteins and carbohydrates form the
cell membrane (B). The cell membrane is a
part of a cell like a neuron (C). A collection
of neurons forms a nervous tissue(D).
Different tissues that function together forms
an organ like the brain(E). The brain is an
integral part of the nervous system (F). The
nervous system is one of the many organ
systems that form an organism such as a
man (G)
Organization

4. Reymon T. Dela Cruz November 2, 2022
Evolutionary Adaptation
Organisms are extremely adapted to their environment. These adaptations
are a result of natural selection. Members of a species with characteristics
that are better suited to the environment leave more offspring. This ensures
that over time, the population becomes more and more adapted to its
environment.
Shark’s streamline body allows it to move fast in water. Its gills
effectively absorb dissolved oxygen in seawater. It also has
mechano-receptors in its lateral line system that detects low
frequency vibrations in the water. Sharks also have
electroreceptors called ampullae of Lorenzini which it uses to
detect bioelectric fields of their prey.

5. Reymon T. Dela Cruz November 2, 2022
Regulation
Living organisms maintain an internal environment that has conditions significantly different
than the external environment. Biological processes occur only at a small range of set
conditions which must be maintained. Organisms have adaptations for controlling osmotic
pressure, temperature and concentration of various substances.
Sweating allows humans to lose excess heat and maintain
an internal body temperature of 37oC on average. In
response to low external temperatures, human muscles
contract automatically to generate heat. This process is
called shivering thermogenesis.

6. Reymon T. Dela Cruz November 2, 2022
Reproduction
Living organisms reproduce their own kind. The process of reproduction allows organisms to
pass their genetic materials to the next generation. Only characteristics encoded in genetic
materials are passed on from parent to offspring through reproduction.
This newly hatched reticulated python is only several
centimeters in length but will grow up to over 20 ft just like
its parents. The net like pattern of the parents are inherited
by the offspring. The pattern serves to camouflage the
snake on the forest floor or on the branch of trees.

7. Reymon T. Dela Cruz November 2, 2022
Irritability
Organisms are capable of detecting and responding to changes in its environment. Organisms
react to various forms of stimuli including visual, tactile, olfactory and auditory. Not only can
living things perceive external stimuli but internal stimuli as well. Notice how we can perceive
hunger even if there are no external stimuli to arouse the sensation?
This Samar cobra raised its head and expanded its ribs
forming a menacing hood in response to visual and
vibration stimuli. This aggressive display is designed to
intimidate would be predators. By raising its head and
forming its hood, it attempts to look larger.

8. Reymon T. Dela Cruz November 2, 2022
Growth and Development
Growth for a unicellular organism means increase in size. For a multicellular organism, growth
means addition of more cells through mitosis. Development on the other hand can be defined
as a series of changes that lead to improved and more complex functioning. Growth and
development happen simultaneously as organisms transition to its mature form.
This elephant hawk moth larva (A) will develop into a
mature hawk moth (B) through a process of
metamorphosis. Although not all transitions are as dramatic
as this example, the transition from immature to mature
form usually involves significant growth and development.
A B

9. Reymon T. Dela Cruz November 2, 2022
Metabolism
Organisms obtain materials from the environment and process it for energy or to create
biological structures. Metabolic processes can be categorized into anabolic and catabolic
processes. Anabolic processes are building-up processes that takes simple reactants to build
a more complex product. Catabolic processes, on the other hand, are breaking-down
processes.
Animals actively obtain organic matter from their
environment as energy source and material source for
growth and development. Having no ability to synthesize
their own food, animals forage and hunt to acquire organic
matter.

10. Reymon T. Dela Cruz November 2, 2022
Cells
All modern organisms are composed of either a single cell (unicellular organisms) or many
cells which work in relation to each other to function as a single complex living thing. Cells are
the basic unit of life which means that the smallest living system is a single cell. Even
multicellular organisms start out in life as a single cell.
All human beings start out in life as a single cell called
zygote. Zygote is simply a fertilized egg. This means that
once an egg cell is fertilized by sperm, a new human being
is produced. In the days that follow, the zygote will undergo
a series of cellular division.

11. Spontaneous Generation
Reymon T. Dela Cruz November 2, 2022
In ancient times, people have a notion
of spontaneous generation – the
development of living organisms from
non-living things.
 Frogs come from mud and develop
during rainy seasons
 Insects come from dew.
 Maggots come from rotting meat.
 There is even a recipe for creating
mice!
Francesco Redi demonstrated that maggots do
not spontaneously form from rotting meat using
a simple but clever experiment.
Louis Pasteur proved that microbes in the air
are responsible for the fermentation process
and that the material itself cannot produce
microbes.

12. Reymon T. Dela Cruz November 2, 2022
Spontaneous Generation
Redi’s set-up Pasteur’s set-up

13. Reymon T. Dela Cruz November 2, 2022
Origin of Life
No one knows exactly how molecular assemblages transition from nonliving to living. Fossils and
isotopic “finger print” of early life forms provide a glimpse of the past although at best, an
incomplete picture. Based on the current data that we have:
 We know that the Earth is approximately 4.6
billion years old.
 There is a Last Universal Common Ancestor
(LUCA), the first true life form.
 The origin of life may be divided into four key
developments
o Abiotic synthesis of organic molecules
o polymerization
o Self-replicating molecules
o Protocells

14. Abiotic Synthesis of Organic Matter
Reymon T. Dela Cruz November 2, 2022
 Mechanisms, materials and conditions must
be present for life to begin.
 Life must have begun in water.
 Atmosphere must be highly reducing.
 Formation of the pre-biotic soup.
Oparin-Haldane Hypothesis
In 1953, Stanley Miller and Harold Urey tested
the Oparin-Haldane hypothesis. They exposed
a mixture of water vapor, methane, ammonia
and hydrogen (their proposed composition of
the Earth’s early atmosphere) to an electric
discharge (simulating thunderstorms). Their
analysis revealed that organic molecules,
specifically amino acids, can be produced
spontaneously from inorganic compounds
under their proposed primitive conditions.

15. Abiotic Synthesis of Organic Matter
Reymon T. Dela Cruz November 2, 2022
 Another possibility is that the first organic
molecules may have been extra-terrestrial.
 Alkaline hydrothermal vents are also being
considered as potential sites where life may
have begun. The conditions around
hydrothermal vents are similar to the
conditions proposed to be present in
primitive earth
Other Hypotheses
 Recent analysis of meteorites that reached
the Earth’s surface, especially
carbonaceous chondrites, revealed that
many contain organic matter like amino
acids, sugars, lipids and nucleotide bases.
 Alkaline hydrothermal vents are rich in
hydrogen, methane, ammonia, iron, sulfur
and other substances that living things
need. It is also known to support diverse
communities of organisms

16. Protocells
Reymon T. Dela Cruz November 2, 2022
 In the metabolism first hypothesis, scientists
propose that the first cells began as a
collection of simple chemical reactions that
happen within the confines of a boundary.
 Having a surrounding membrane could have
enabled protocells to perform metabolic
processes that cannot be done in the
external environment.
 It may have also protected the protocells’
genetic materials.
 Recent studies of abiotically synthesized
vesicles support the idea of protocells.
Vesicles that are abiotically produced in the
laboratory exhibits properties we associate
with life such as metabolism, reproduction
and homeostasis.
 John Szostak and his colleagues were able
to create vesicles capable of replicating
RNA, an ability that could have enabled
protocells to reproduce.

17. First True cells
Reymon T. Dela Cruz November 2, 2022
 The first true cells may have been
unicellular prokaryotes.
 Stromatolites (fossilized imprint of biofilms)
suggest that prokaryotic cells may have
been present some 3.5 billion years ago.
 The first true cells were most likely
heterotrophic anaerobes.
 Chemosynthesis is probably evolved before
photosynthesis based on the gradual
increase in the amount of atmospheric
oxygen which began 2 billion years ago.
 The first eukaryotes may have evolved 1.8
billion years ago.
 The evolution of eukaryotes may have
resulted from prokaryotic endosymbionts
evolving to an organelle of a larger
prokaryote that engulfed it.
 organelles with their own genetic materials
may have been evolved through a process
called serial endosymbiosis.