Transcript Chapter 12 Modern Materials - 中正大學化學系

生命的化學
『從原子到宇宙』課程第十週
胡維平
國立中正大學化學暨生物化學系
11/19/2015
生命的定義?
• the condition that distinguishes organisms from inorganic objects
and dead organisms, being manifested by growth through
metabolism, reproduction, and the power of adaptation to
environment through changes originating internally.
• life is a member of the class of phenomena that are open or
continuous systems able to decrease their internal entropy at the
expense of substances or free energy taken in from the environment
and subsequently rejected in a degraded form.
• At a higher level, living beings are thermodynamic systems that
have an organized molecular structure.That is, life is matter that can
reproduce itself and evolve as survival dictates. Hence, life is a selfsustained chemical system capable of undergoing Darwinian
evolution.
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Life is complex chemical processes.
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光合作用
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呼吸作用
生物分子
Amino Acids and Proteins
• Proteins are polymers of amino acids.
• A condensation reaction
between the amine end of one
amino acid and the acid end of
another produces a peptide
bond.
20
amino
acids
Proteins
• Hydrogen bonding in peptide chains causes
coils and helices in the chain.
• Kinking and folding of the coiled chain
gives proteins a characteristic shape.
• Most enzymes are proteins.
• The shape of the active site complements
the shape of the substrate on which the
enzyme acts; hence, the “lock- and-key”
model.
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Carbohydrates
Simple sugars are polyhydroxy
aldehydes or ketones. In solution,
they form cyclic structures.
Lipid
Nucleic Acids
Two of the building blocks of RNA
and DNA are sugars (ribose or
deoxyribose) and cyclic bases
(adenine, guanine, cytosine, and
thymine or uracil).
1953 Watson and Crick
discovered the structure of
DNA and solve the mystery of
genetics
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DNA Replication
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Protein Synthesis
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Origin of Life
Life on earth began ~35 byr ago.
Where did the water come from?
How were the biomolecules synthesized?
How did the first life begin?
Is the Universe fine-tuned for life?
地球上的水從哪裡來?
From volcanoes?
From comets?
Evolution of Life, Common Ancestor
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Conducted in 1952by Stanley Miller, under the
supervision of Harold Urey,
From RNA World to
DNA World?
RNA can store information and
can act as an enzyme