Amino Acid: A Class of Organic Molecules Composed of 20 Amino Acids

Protein:
Protein is a class of nitrogenous organic compounds which have large molecules composed of
one or more long chains of amino acids and are an essential part of all living organisms,
Amino Acid:
An amino acid is an organic molecule that is made up of a basic amino group (−NH2), an acidic
carboxyl group (−COOH), and an organic R group (or side chain) that is unique to each amino
acid. The term amino acid is short for α-amino [alpha-amino] carboxylic acid.
There are 20 amino acids that make up proteins and all have the same basic structure, differing
only in the R-group or side chain they have.
Types of amino acids:
1. Essential amino acid;
An essential amino acid, or indispensable amino acid, is an amino acid that cannot be
synthesized by the organism at a rate commensurate with its demand, and thus must be supplied
in its diet.
The 9 essential amino acids
are: histidine, isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan,
and valine
2. Non essential amino acids:
Nonessential means that our bodies produce an amino acid, even if we do not get it from the
food we eat. Nonessential amino acids include: alanine, arginine, asparagine, aspartic acid,
cysteine, glutamic acid, glutamine, glycine, proline, serine, and tyrosine.

Functions of Proteins:
Protein plays an essential role in many bodily functions, including recovery and repair of tissues
in the muscles, skin, organs, blood, hair and nails
Functions performed by proteins can be divided into different categories. Some functions are
essential at the cellular level while others are required for the better performance of the body as a
whole. Here, we will try to understand different functions performed by proteins in our body
through various examples.
1. All enzymes are proteins:
Enzymes are the proteins that are required for any chemical reaction to take place in our body.
They catalyze the biochemical reaction so that life can proceed. An example of enzymatic
reaction in our body is glycolysis. This is the process by which energy is released from a glucose
molecule. This energy is required to carry out several processes taking place within a cell. The
process of glycolysis involves around 10 steps each requiring a particular enzyme. The absence
of a single enzyme stops the process and energy from glucose cannot be obtained.
Synthesis of proteins also requires specific enzymes. Thus, from obtaining energy to making
proteins, all chemical processes in living organisms need enzymes, and all enzymes are proteins.
The role of proteins as enzymes is the most important and crucial function performed by
proteins.
2. Proteins act as receptors on cell membranes
Proteins are essential components of all the cell membranes and membranes of the organelles.
One of the functions of these membrane proteins is that they act as receptors. Hormones,
neurotransmitters, and other signaling molecules bind to these receptors and convey signals to
cells. In this way, proteins play a role in cell signaling that is essential for the coordinated
function of all the cells present in our body. Take the following example to understand the role
of proteins as receptors.
 Insulin is a hormone that controls the glucose levels in our blood. It performs its function
by binding to its receptor that is a protein. Insulin binds to its receptor that sends signals
for the opening of glucose channels so that glucose can be taken up from the blood into
the liver and muscle cells. If the insulin receptors are not present, the blood glucose levels
cannot be regulated.
This and various other examples in our body prove why proteins are necessary for cell signaling
and coordination of cellular functions.