BIOMOLECULES
They are the building blocks of life. Biomolecules
make up cells and perform important functions in living things. They are mainly
composed of carbon, hydrogen, oxygen, nitrogen, sulphur and phosphorus.
ORGANIC BIOMOLECULES ARE
EXCLUSIVE TO LIVING THINGS, they are large molecules made up of many atoms.
CARBOHYDRATES
They are the most abundant, they are made up of
saccharides or sugars, for example glucose or fructose.
Function: They are responsible for storing and
transporting energy. However, others are structural components, e.g. cellulose.
Examples:
Sucrose –
it is a disaccharide (made up of two sugars, glucose and fructose).
Cellulose-it
is a polysaccharide, made up of many sugars, it is responsible for the cell
wall structure of plants.
Starch
(almidón)- it is a polysaccharide, responsible for storing energy. Pasta and
rice contain starch.
LIPIDS (FATS)
Lipids are insoluble in water and difficult to digest.
They perform many functions in living things.
Examples:
Fats and oils- they store energy.
Phospholipids-are the fundamental structure of cell
membranes.
Steroids- They act as sexual hormones or vitamin D.
Waxes (ceras) – are produced by animals and plants as
protection.
Lipids
release a lot more energy than carbohydrates once digested.
PROTEINS
These are
macromolecules (large molecules) with very complex structures, made up of
chains of smaller molecules called aminoacids.
Functions:
Their functions are very varied.
-They give structure to cells, e.g. collagen in the skin.
-They transport substances around the body e.g.
haemoglobin transports oxygen in the red blood cells.
- They regulate chemical reactions e.g. enzymes
- They protect our body from bacteria and other
microorganisms e.g. antibodies
NUCLEIC ACIDS
These are also macromolecules,
they are formed by the union of smaller molecules, nucleotides. Nucleic acids
make up the genetic material of cells, that is the DNA or RNA.
EXAMPLES:
-
Deoxyribonucleic acid or DNA: it is
found in the cell nucleus and makes up the chromosomes. It stores the
information necessary for the functioning of the cell. It contains hereditary
information.
-
Ribonucleic acid or RNA: It is found in the cytoplasm. It participates
in the synthesis of proteins.
INORGANIC
BIOMOLECULES
THEY ARE NOT
EXCLUSIVE TO LIVING THINGS. They are small molecules made up of
very few atoms.
-Water: it is the most abundant substance in living
beings. It makes up about 65% of your body. It is present in tissues, organs,
blood and even in your teeth. It is used to carry out all the chemical
reactions. It is also needed to transport substances and to regulate the body
temperature.
-Mineral salts form the solid structure of living
beings, such as skeletons, nails, horns, beaks etc. Mineral salts are also
involved in chemical reactions and they are necessary for the transmission of
nervous impulses.
Activity
Proteins are formed by chains of 20 different
aminoacids.
a)
Imagine that proteins were made up of
only two different amino acids called aa1 and aa2. Write the possible kinds of
proteins combining the amino acids in a chain of three. For example aa1 + aa1 +
aa1
b)
Changing one amino acid in a chain
can produce
c)
a completely different protein. Do
you think this fact is related to the wide variety of living things on Earth?