4. Not all chemicals are required for Life
Fewer than 30 of the more than 90 naturally occurring chemical
elements are essential to organisms.
5. They extract, transform
and use energy from the
environment
They can sense and respond to
alterations in their surroundings
They have the capacity for
precise self-replication and self-
assembly
Life is
dynamic
What makes life different from non-life?
8. There is relative chemical simplicity in the “mineral world” as compared to the complexity of
the “plant and animal worlds”
- Antoine- Laurent Lavoisier (1743–1794)
Biomolecules are extremely complex
All biomolecules are compounds of
carbon with a variety of functional
groups.
9. Carbon: The central element of life
Carbon accounts for 0.09 % in earth’s crust, but more than half the dry weight of cells.
Carbon can form single bonds with hydrogen atoms, and both single and double bonds with
oxygen and nitrogen atoms.
A carbon atom can form very stable single, double or triple bonds with another carbon atom.
The bonding versatility of carbon, with itself and with other elements, was a major factor in the
selection of carbon compounds for the molecular machinery of cells.
10. Covalently linked carbon atoms in biomolecules can form linear chains, branched chains,
and cyclic structures.
No other chemical element can form molecules of such widely different sizes, shapes, and
composition.
Most biomolecules can be regarded as derivatives of hydrocarbons, with hydrogen atoms
replaced by a variety of functional groups that confer specific chemical properties on the
molecule.
Many biological molecules are macromolecules, which are polymers of relatively simple
precursors.
The major biological macromolecules fall into 4 classes:
Carbohydrates
Proteins
Lipids
Nucleic acids
Carbon based macromolecules are key to life
11. Organic molecules can be synthesized in the lab
In 1828, Friedrich Wöhler
synthesized the organic
compound urea by heating the
inorganic compound, ammonium
cyanate.
This experiment showed for the first time that
compounds found exclusively in living organisms could
be synthesized from common inorganic substances.
13. Is life inherent in biomolecules?
● Goat pathogen Mycoplasma mycoides genome
(~1.2 million bp of DNA) was artificially
synthesized.
• Transferred the synthetic genome to
Mycoplasma capricolum.
• Mycoplasma mycoides JCVI-syn1.0
• The cost: About $40 million
14. Biochemical Unity Underlies Biological Diversity
“What is true of E. coli
is true of the elephant.”
- Jacques Monod (1954)
15. Life is sustained by utilizing energy
To be in order
requires spending
of energy
20. • Life is manifested at the level of
cells(micro-scale) to that of the
biosphere (mega-scale) through:-
• the nano-scale biomolecules and
their interactions with each other
• and by the process of metabolism
which keeps life in order.
• At biochemical level, diverse
organisms show surprising
similarity.
Biochemistry explains the Molecular Logic of Life
