2. PROTEINS
• Proteins are vital components of
all living systems. Proteins are
present in the different parts of
the body like the muscles, skin,
nails and others. They serve as
catalysts, transport oxygen, serve
as hormones in the regulation of
specific body processes, and act
as antibodies and blood clotting
agents. Among the most important
proteins in the body are enzymes,
hormones, and other components of
chromosomes and cell membranes.
• Proteins contain the elements
carbon, nitrogen, oxygen,
hydrogen, and sulfur. Elements
like phosphorus and iron are also
found in some forms of proteins.
Hemoglobin, a protein found in red
blood cells, contains iron that
helps it attract and transport
oxygen in the body.
3. PROTEINS
• Proteins are polymers
formed from amino acids
bound by peptide bonds.
They are also called
polyamides. Most proteins
are combinations of the 20
different naturally
occurring amino acids. The
human body does not store
protein, which is why it
is important that you
include protein-rich food
like beef, poultry, dairy
products, and leguminous
plants like beans and nuts
in your diet.
4. What are the functions of
proteins in biomolecules?
• Proteins serve as structural
support, biochemical catalysts,
hormones, enzymes, building
blocks, and initiators of cellular
death. Proteins can be further
defined by their four structural
levels: primary, secondary,
tertiary, and quaternary.
5. Amino Acids
• Amino acids are the monomers that make up proteins. They
contain the functional groups amine (-NH2) and carboxylic
acid (-COOH).
• Amino acids found in proteins are a-amino acids (alpha-amino
acids). This is because the amino and carboxyl groups are
attached to a central carbon called the a-carbon (alpha-
carbon).
• The R or the side chain may contain H, CH3, or other
functional groups; the nature of these side chains
differentiates a-amino acids from one another. The figure
below shows the 20 amino acids normally found in proteins.
You will notice that they have the same basic structure but
different side chains.
6. Enzymes
Function: Catalyze metabolic reactions like digestion
and production of biosynthetic molecules.
Example: Lactase - breaks down lactose in milk
Nitrogenase - gives protein complex for nitrogen
fixation
7. Hormones
Function: Regulate metabolism and growth of the
organism.
Example: Insulin - regulates glucose metabolism
Oxytocin - stimulates contraction during
childbirth
8. Storage Proteins
Function: Serve as
a reservoir of
essential nutrients
ormaterials needed
by the cell or
organism.
Example: Zein
provides
nourishment in
germinating seeds
9. Structural Proteins
Function :
Provide structure
and support for
the cell or
organism.
Example: Keratin
- serves as major
component of
hair, feather,
nail, and beak
Collagen - serves
as major
component of
connective
tissues
11. Transport Proteins
Function: Transport
of molecules or
ions throughout the
cell or organism.
Example:
Hemoglobin -
carries oxygen
through the blood
Cytochrome -
transports
electrons
12. Protective Proteins
• Function: Identify and combat infectious organisms
that enter the cell or the body of the organism.
• Example:
• Immunoglobulin - fights bacteria that invade the body
• Thrombin - enables blood clotting
