In this video you will learn that proteins
are natural polymers made up of amino acids
and we find out why they have to be an essential part of our diet
For healthy living proteins need to make up about 10% of the food we eat
Plant seeds such as cereals, nuts, pulses (beans) are good sources of protein
As are most animal products such as insects, fish, meat, eggs, and milk
Proteins have two major functions in living things
They are the enzymes that control all of the reactions that take place in the cells of all living things
And they form the structural material in animals, hair, bone, skin, muscles and the vital organs
Proteins are natural polymers made up of 20 different amino acids
Look at the central carbon atom. It has four different groups attached to it
The amino group, the acid group, the hydrogen atom, and the side chain, R.
There are 20 different groups of atoms for R.
For example, hydrogen, methyl, alcohol, etc.
Organic compounds with two or more functional groups have the potential to polymerize
Think of them like trucks of a train. The couplings are like the functional group.
With only one group, you can only make a double molecule.
But with two or more functional groups, you can make a long chain.
This coupling works chemically by a condensation reaction
where water is eliminated between the amino and acid groups
making a peptide link.
We begin the formation of polypeptides and eventually proteins.
When we digest proteins it breaks back into the separate amino acids,
so we can reassemble them into our own proteins.
Enzymes have a primary structure.
which is simply the polypeptide chain we have just seen.
The secondary structure enables the protein to coil up like a twisted rope.
Now the different side chains attached to each amino acid
represented by the different colored Rs
Stick out like bits of rag caught in the rope.
Some of these will attract each other and some will repel
enabling the rope, our protein, to coil up in a very specific 3-D shape
giving it its Tertiary structure.
Here's how it works
The genetic code of living things
safely stored as DNA on the chromosomes in the nucleus of cells
sends out a coded message telling the cell to construct a protein
made of amino acids joined together in a unique order
this coils up into its final 3D shape
ready to catalyze one type of reaction needed by the cell.
Finally a bit about the structural proteins that build the body of animals
such as worms, insects, birds, fish and ourselves.
Our biggest organ is our skin made of tough protein.
Bones are made of a flexible tough protein,  called collagen.
Try feeling your ears.
Then calcium phosphate a hard brittle insoluble salt
is laid down
making the bone a bit like reinforced concrete
with the tough flexible collagen fibers like steel
an the hard brittle cement around.
Protein molecules in muscles are spread out
and they contract when activated
Spiders and some insects make threads out of proteins.
They are very strong and tough
but soft.
So to summarize, we learned that
Proteins are vital to all living things
since they are the enzymes that control all the chemical reactions in their cells
In addition, animals use proteins to build their vital organs
Digestion breaks the protein we eat
into amino acids
which we can reassemble into the proteins we need.
