What Is A Protein
A protein is an organic compound made of a long train of amino acids linked together. They contain nitrogen in addition to carbon, hydrogen, and oxygen (some contain sulfur and phosphorous). The process of making a protein involves various parts of a cell, the nucleus and the cytoplasm. When a cell receives a signal saying that a certain protein is needed, the code for producing protein is made.
What Function Do They Have?
Most of the chemical reactions which occur in biological systems are catalyzed by enzymes, which are proteins
They can provide structure (ligaments, fingernails, hair)
Help in digestion (stomach enzymes)
aid in movement (muscles)
play a part in our ability to see (the lens of our eyes is pure crystalline protein)
What Does A Protein Do Next?
Once a protein is made it moves to a particular part of the cell where it is needed, or the cell packages it up and sends to other another cell or other parts of the body.
This process is like putting groceries (proteins) in a bag at the store (the cytoplasm where they are made), taking them home (moving them somewhere else), then using them for various purposes (eggs for cooking, milk for drinking, chocolate for munching …).
Ten of the twenty amino acids needed to build proteins can be manufactured internally by metabolic reactions. The remaining ten amino acids cannot be made by the body and therefore must be taken in with the diet; these are the essential amino acids. Most animal proteins supply all of the essential amino acids. Vegetables may be lacking in one or more of the essential amino acids. Persons on strict vegetarian diets must learn to combine foods, such as beans with rice or wheat, to obtain all the essential amino acids. The few essential fatty acids that are needed are easily obtained through a healthful, balanced diet.
About a sixth of your total calorie intake should ideally be obtained from protein.
Protein in our diets comes from both animal and vegetable sources.
Most animal sources (meat, milk, eggs) provide what’s called “complete protein,” meaning that they contain all of the essential amino acids.
Vegetable sources usually are low on or missing certain essential amino acids.
For example, rice is low in isoleucine and lysine. However, different vegetable sources are deficient in different amino acids, and by combining different foods you can get all of the essential amino acids throughout the course of the day.
Other sources contain quite a bit of protein — things like nuts, beans, soybeans, etc. are all high in protein. By combining them you can get complete coverage of all essential amino acids.
How The Body Deals With Protein
The digestive system breaks all proteins down into their amino acids so that they can enter the bloodstream. Cells then use the amino acids as building blocks as described in ‘From Inside-Out’.
Excess protein is converted into fat in the body. A high protein diet therefore may lead to obesity
forms of food allergy which involve the most profound immune mechanisms. Delayed reactions begin in the gastrointestinal tract mucosa and spread inward to any body tissue if food proteins enter the circulation and interact with the circulating immune system. Incoming food protein/antigens tend to form immune complexes, and can injure target organs by triggering inflammatory responses in a variety of ways.
After water, the next largest percentage of material in blood plasma is protein. Plasma proteins include the following:
Albumin – the most abundant protein in plasma is important for maintaining the osmotic pressure of the blood. This protein is manufactured by the liver
blood clotting factors – also manufactured in the liver
antibodies – combat infection
a system of enzymes made of several proteins, collectively known as ‘complement’, helps antibodies in their fight against pathogens
The Recommended Daily Allowance (RDA) to fulfill protein needs is equal to 0.8 g of protein per kg body weight per day.
Individuals undergoing endurance training increase their protein needs to about 1 to 1.2 g per kg per day. In contrast, for subjects performing resistance exercises or weight lifting, the RDA for protein seems to be adequate. However The World Health Organization more conservatively puts our dietary protein needs at about 0.45 grams of protein per kilogram of ideal body weight.
There is no place in the body to store protein. We need to consume enough protein to allow our muscles to be healthy and perform work.
“The machinery of life depends on proteins–large organic molecules composed of tens, hundreds or even thousands of amino acids bound together and folded into specifically shaped structures. How they fold into these three-dimensional structures is known as the second genetic code and is one of great challenges in science today. Join UCSD biophysicist Jose Onuchic, as he explores how physics, chemistry, biology and mathematics are all being applied to crack the protein folding mystery”
The growth and survival of living things depends on how the information in double-stranded DNA is transcribed into RNA, the single-stranded messenger molecule, and translated into a sequence of amino acids to synthesize specific proteins.