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LESSON 1: CHEMISTRY OF LIFE
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Lessons:
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Overview
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 When
we talk about life and its basic requirements, what do we need to
consider? There are chemical and physical requirements, energy
requirements, and information storage and retrieval requirements. In
this lesson we will look at the chemical and physical properties
that molecules, cells, and organisms have to obey. We will look at
some of the chemical properties of the six most important elements
of life – carbon, nitrogen, oxygen, hydrogen, phosphorous, and
sulfur. We will also introduce the concept of the 12 key
intermediates that are the basis for all of the 75-100 known
building blocks in cells. Then we will look at some of the important
classes of
macromolecules,
proteins,
lipids,
carbohydrates, and
nucleic acids, used to build cells. Keep track of
where these macromolecules are found by visiting the
Cell module often.
Learning Objectives
Topics covered in this Lesson
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All living things are made up of
chemical compounds. Chemical interactions are therefore a
crucial component of life. Here you will learn that the
majority of living tissue is made up of only a few elements.
In addition, there are only five main types of chemical
interactions that are found in chemical compounds.
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Learning Objectives
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Understand that the molecules
that make up cells must obey physical and chemical laws.
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Know that atoms are composed of
protons, neutrons, and electrons.
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Ionic bonding
involves the transfer of an electron from one atom to
another, leading to two charged ions that are attracted
to each other.
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Be able to define
covalent bonding.
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Know that covalent bonds may be
polar or
nonpolar.
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Hydrogen bonds
form when a positively charged hydrogen of one molecule
is attracted to a negatively charged region of another
molecule.
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Be able to describe
hydrophobic
interactions, using water and oil as an example.
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Understand that
Van der Waals forces are weak attractions
between the nucleus of one atom and the electrons of
another.
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 Organisms
are composed of from forty to fifty percent water to over ninety
percent water. In addition, most of the important chemical reactions
of life take place in water. Because of these and other reasons,
there is no doubt that water is essential for life as we know it.
Ultimately, water’s importance can be attributed to its chemical
structure. Water’s chemical structure gives it some important
properties that help make life possible.
Learning Objectives
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Understand why water is the
universal solvent - its polar structure allows it to
dissolve almost any
polar or charged substance.
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Be able to link the constantly
forming, breaking, and re-forming
hydrogen bonds
in water to its many important properties such as its high
heat capacity, high heat of fusion, high heat of
vaporization, cohesion, adhesion, and surface tension.
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Know that pH is the negative log of
the proton concentration of a solution and provides a
measure of how acidic or basic a solution is.
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A
pH above 7 is considered basic while a pH below 7
is considered acidic.
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 There
are twelve key compounds that are found in the metabolic pathways of
all organisms. Although we won’t be memorizing a lot of structures
and chemical formulas, the fact that these same intermediate
compounds are found everywhere has interesting evolutionary
ramifications. Think about it.
Learning Objectives
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Know that twelve key
intermediate compounds are used to synthesize all of the
75-100 building blocks,
coenzymes, and
prosthetic groups in every organism on the planet.
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The twelve key intermediates
were originally discovered in bacteria but have
subsequently been found to be important in the cells of
all organisms.
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