2 Water, the Solvent
of Life
© 2021 Macmillan
Learning
, Principle 1 (5 of 5)
The solvent properties of water shaped the
evolution of living things. Most small intermediates
of metabolism, as well as nucleic acids and proteins,
are soluble in water. Lipid bilayers, the likely
forerunners of biological membranes, form
spontaneously in water and are stabilized by their
interaction with it. Although hydrogen bonds, ionic
interactions, and the hydrophobic effect are individually
weak, their combined effects powerfully influence the
three-dimensional shape and stability of biological
molecules and structures.
, Principle 2 (1 of 3)
The ionization behavior of water and of weak acids
and bases dissolved in water can be represented
by one or more equilibrium constants. Most
biomolecules are ionizable; their structure and function
depend on their ionization state, which is characterized
by equilibrium constants.
, Principle 3 (1 of 5)
An aqueous solution of a weak acid and its salt
makes a buffer that resists changes in pH in
response to added acid or base. Biological systems
are buffered to maintain a narrow pH range, in which
their macromolecules retain their functional structure,
which depends on their ionization state. Conditions that
produce blood pH outside the range of 7.3 to 7.5 are
life-threatening in humans.
of Life
© 2021 Macmillan
Learning
, Principle 1 (5 of 5)
The solvent properties of water shaped the
evolution of living things. Most small intermediates
of metabolism, as well as nucleic acids and proteins,
are soluble in water. Lipid bilayers, the likely
forerunners of biological membranes, form
spontaneously in water and are stabilized by their
interaction with it. Although hydrogen bonds, ionic
interactions, and the hydrophobic effect are individually
weak, their combined effects powerfully influence the
three-dimensional shape and stability of biological
molecules and structures.
, Principle 2 (1 of 3)
The ionization behavior of water and of weak acids
and bases dissolved in water can be represented
by one or more equilibrium constants. Most
biomolecules are ionizable; their structure and function
depend on their ionization state, which is characterized
by equilibrium constants.
, Principle 3 (1 of 5)
An aqueous solution of a weak acid and its salt
makes a buffer that resists changes in pH in
response to added acid or base. Biological systems
are buffered to maintain a narrow pH range, in which
their macromolecules retain their functional structure,
which depends on their ionization state. Conditions that
produce blood pH outside the range of 7.3 to 7.5 are
life-threatening in humans.
