Biochemistry
1. What are the chemical elements that form most of living biological matter?
The chemical elements that form most
of the molecules of living beings are
oxygen (O), carbon (C), hydrogen (H)
and nitrogen (N).
2. Living beings are made of
organic and inorganic
substances. According to the
complexity of their molecules
how can each of those
substances be classified?
Inorganic substances, like water,
mineral salts, molecular oxygen and
carbon dioxide, are small molecules
made of few atoms. Organic substances,
in general, like glucose, fatty acids and
proteins, are much more complex
molecules made of sequences of
carbons bound in carbon chains. The
capacity of carbon to form chains is one
of the main chemical facts that
permitted the emergence of life on the
planet.
3. What are the most
important inorganic molecular
substances for living beings?
The most important inorganic
substances for living beings are water,
mineral salts, carbon dioxide and
molecular oxygen. (There are several
other inorganic substances without
which cells would die.)
4. What are mineral salts?
Where in living beings can
mineral salts be found?
Mineral salts are simple inorganic
substances made of metallic chemical
elements, like iron, sodium, potassium,
calcium and magnesium, or of non-
metallic elements, like chlorine and
phosphorus.
They can be found in non-solubilized
form, as part of structures of the
organism, like the calcium in bones.
They can also be found solubilized in
water, as ions: for example, the sodium
and potassium cations within cells.
5. What are the main
functions of the organic
molecules for living beings?
Organic molecules, like proteins, lipids
and carbohydrates, perform several
functions for living organisms.
Noteworthy functions are the structural
function (as part of the material that
constitutes, delimits and maintains
organs, membranes, cell organelles,
etc.), the energetic function (chemical
reactions of the energetic metabolism),
the control and informative function
(genetic code control, inter and
intracellular signaling, endocrine
integration) and the enzymatic function
of proteins (facilitation of chemical
reactions).
6. What are some examples of
the structural function of
organic molecules?
Organic molecules have a structural
function as they are part of cell
membranes, cytoskeleton, organ walls
and blood vessel walls, bones, cartilages
and, in plants, of the conductive and
support tissues.
7. What are some examples of
the control and informative
function of organic molecules?
Based on genetic information, organic
molecules control the entire work of the
cell. The nucleic acids, DNA and RNA,
are organic molecules that direct the
protein synthesis, and proteins in their
turn are the main molecules responsible
for the diversity of cellular biological
tasks. In membranes and within the
cell, some organic molecules act as
information receptors and signalers.
Proteins and lipids have an important
role in the communication between cells
and tissues, acting as hormones,
substances that transmit information at
a distance throughout the organism.
8. What are biopolymers?
Polymers are macromolecules made by
the union of several smaller identical
molecules, called monomers.
Biopolymers are polymers present in the
living beings. Cellulose, starch and
glycogen, for example, are polymers of
glucose.
