Protein is composed of amino acids linked together in chains. It is essential for life and is contained in every part of the body. There are two main types of protein - fibrous proteins found in animals that serve structural functions, and globular proteins that usually do not have structural roles and can be enzymes or transporters. Protein has critical physiological functions including building, maintaining, and repairing body tissues, and can also be converted to energy when intake is greater than requirements. The structure of proteins involves four levels - primary, secondary, tertiary, and quaternary.

1. Lesson Demonstrators
Elixir Shalinee Li P. Dayday
Elixir Christopher S. Bandoquillo
Elixir Victor F. Melitante Jr
Elixir Juan Carlos J. Lagahit

2. Protein is a chain of amino acids joined by peptide
bonds in a specific sequence.
Protein is an essential nutrient. There is no life
without protein. Protein is contained in every part of your
body, the skin, muscles, hair, blood, body organs, eyes,
even fingernails and bone. Next to water, protein is the
most plentiful substance in your body.
(Lauritzen, Georgia C.)

3. Fibrous proteins are found only in animals.
They usually serve as structural entities — for
example, connective tissue, tendons, and muscle
fiber. They are normally insoluble in water.
Globular proteins usually do not serve a
structural function — they act as transporters, like
hemoglobin, and are often enzymes. They are
usually water-soluble

4. Protein has a critical physiological function. Protein
is primarily used in the body to build, maintain, and repair
body tissues.
In the event that protein intake is greater than that
required by the body for this primary function, excessive
protein is converted to energy for immediate use or
stored in the body as fat.
Protein energy will be used only after other energy
sources (carbohydrate and fat) are exhausted or
unavailable.

5.  Protein is vital in the maintenance of body tissue,
including development and repair.
 Protein is the major source of energy.
 Protein is involved in the creation of some
hormones, help control body functions that involve
the interaction of several organs and help regulate
cell growth.
 Protein produces enzymes that increase the rate
of chemical reactions in the body.

6.  Proteins transport small molecules through the
organism. Hemoglobin is the protein that
transports oxygen to the cells and it is called as
transport protein.
 Proteins called antibodies help rid the body of
foreign protein and help prevent infections,
illnesses and diseases.
 protein help store other substance in the organism.
For example, iron is stored in the liver in a
complex with the protein ferritin.

7.  Proteins help mediate cell responses, such as the
protein rhodopsin, found in the eye and involved in
the vision process.
 Proteins make up a large protein of muscle fiber
and help in the movement of various parts of our
bodies.
 Skin and bone contain collagen, a fibrous protein

8. Proteins are composed of small units. These
units are the amino acids which are called the building
blocks of protein. There are about 20 different amino
acids which are commonly known.
Each different protein is composed of various
amino acids put together in varying order with almost
limitless combinations. Most proteins are large
molecules that may contain several hundred amino
acids arranged in branches and chains.

9. Biochemists have distinguished several levels of
structural organization of proteins. They are:
1. Primary structure
2. Secondary structure
3. Tertiary structure
4. Quaternary structure

10. Elixir JUAN CARLOS
J.LAGAHIT

11. Elixir SHALINEE LI P. DAYDAY

12. Elixir CHRISTOPHER S. BANDOQUILLO

13. Elixir VICTOR F. MELITANTE JR.