Our Journey to Cosmos of the Cell - Origins
Cells are a
of Biology... the
Unity of LIFE...
CMB is the study of the
the basic unit of LIFE is the
an inanimate mixture of
have been selected
reactions that characterize and
Every living thing
"The only life we know for
certain is cellular..."
-biologist & philosopher
all class readings: are on the class
but, have you ever seen an
[ pics of
- HeLa cells in
frozen cultured cells show no signs of
life, not even simple chemical metabolism, if warmed to room temp...
seem to come back to life"... they
move about, feed and metabolize, maybe reproduce.
Collection - Manassas, VA
for centuries, life was defined in the unit of the
a cat, a bird, a human being...
but today life is
of the lives of many
making up a human body...
may be best defined in terms of the individual CELL,
some ideas about life through the scientific age
exactly defines Life ?
biologists agree: life
exhibits certain "QUALITIES"
that equate to the living state and many
prefer to use an operational
description of what living
entities can do and perform
rather than to
use a strict
thus we describe the
Attributes of the Living State:
Self-Replication of cells by cell division (Mitosis
copies of genome: maternal
& paternal hereditary info:
all cells store their hereditary
information in DNA, coded as genes.
of sequenced genomes*)
based in the
semi-conservative replication of DNA (complementary
► most defining
trait of the living state…
Life had an Origin
Life begets Life...
"all cells are derived from preexisting cells"...
Prime Directive: Rudolph
states (1858) this as a prime directive of life.
all individual organisms come from a single cell
& all individual cells in an
organism are descended from fertilized egg.
All living things have evolved from a common
ancestral cell, through processes that include
natural selection and
genetic drift acting on heritable genetic
supporting evidence that all cells are derived from a single
This hypothesis is based upon the
in all current known living organisms, such as:
1. all living things are
composed of very similar
proteins, lipids, carbohydrates, similar
nucleic acids etc...
proteins, the biological catalysts responsible for life's chemical
are made from one set
of 20 standard
acids & L-stereoisomers...
3. all contemporary
organisms carry their genetic information in nucleic acids [DNA/RNA]
and use the
Life exhibits EMERGENT
a large scale, group behavior in a system,
seem to have any clear explanation in terms of the system's
- colorless, odorless, tasteless, reactive
GAS that supports
colorless, odorless, tasteless,
reactive GAS that is flammable
H2O - a non-flammable chemically
reactive polar LIQUID that exist in 3 phases
ex: metal Na is explosive &
gas chlorine is poisonous --> edible table salt
unexpected, nontrivial results of
relatively simple interactions by
relatively simple components. Emergent properties seem to be a
consequence of complexity
from which unpredicted behaviors and patterns emerge.
mix of biomolecules
thus emerges a complexity that exhibits properties we call
Life requires a Critical
Structural complexity and
information content are built up according to current paradigm
by combining simpler subunits into multiple complex combinations.
elements --> stable monomers --> polymers -->
metabolism --> supramolecular complexes --> organelles --> cells*
has no concept of the whole.
A cell runs by the
chemical rules built into its molecules.
A single cell can't do much without interaction with other cells,
but in combination
produce complex results such as
autonomy, i.e., it carries on & regulates
biochemical activities in cells transform
energy (ATP) & molecules to sustain cells
occurs via a few basic molecular reaction mechanisms
in all cells...
capture of light energy in
electron flow through carrier proteins,
Life is a chemical
it consumes free energy, largely derived from photosynthesis, which is stored in
concentration gradients. The release of this
is coupled to thermodynamically unfavorable reactions to
drive biological processes:
no unique Laws
of chemistry or physics
just for the Living State...
Life is manifest by the
absence of the living condition...
a lack of
the properties of the living state is itself definitional of living state.
a deterministic event,
When metabolism ceases with
no prospect of starting again;
Cell death is the collapse of the quantum state which has allowed living
matter to take energy from the
environment, while preventing an increase local entropy and
the tendency of energy to be
dispersed or diffused.
death is an irreversible final state.
organisms will never return to life
because they would be violating the Law of Entropy.
LAW OF ENTROPY CAN BE TEMPORARILY
BUT IT CAN NEVER BE
is process of aging.
is a phenomena where isolated cells show
a limited ability to divide in culture. The successive shortening of the
is also believed to influence the vitality of the cell, thus contributing to
death plays a considerable role during physiological processes of multicellular
particularly during embryogenesis and metamorphosis...
programmed cell death
is known as...
the attributes of life
Definition of a Cell...
A living cell may be described as a(n)...
contained... self assembling... self adjusting... self perpetuating...
(steady & ambient) mix of
... held in a 3-D conformation by
weak non-covalent forces,
... that can
raw materials (precursors) &
from its surroundings,
... & that can
with specific biocatalysts (enzymes),
which it makes itself ,
... & that shows great efficiency & economy of
... & that maintains a
dynamic steady state
far from equilibrium,
... & can
using the linear information
in the "molecule of life"…
But where did the first cells come from?
Universal Characteristics of Cells*