Fundamentals of Human Nutrition/3.1 Defining Proteins
All living cells are made up of proteins (n.d.) including substances such as hormones, enzymes and antibodies that are necessary for that organism to function correctly. Proteins are essential for life. They are a group of complex organic chemical compounds that are made up of carbon, hydrogen, oxygen and sometimes sulfur that is composed of one or more chains of amino acids. They are the true workhorses of the body. Proteins perform a vast array of functions within living organisms, including replicating DNA, catalyzing metabolic reaction and responding to different stimuli. They are an essential part of an organism and take part in nearly all processes that go on with the cells. They are extremely essential in animal diets as some amino acids cannot be synthesized and must be obtained from our food. Amino acids are used in metabolism after they are broken down through digestion.
Some foods that are rich in Proteins include eggs, milk, meat, fish, tofu and legumes.
There are three different types of Proteins based of their composition.
- Simple proteins
- Conjugated proteins
- Derived proteins
Simple proteins are proteins that are made up of amino acids joined by peptides bonds. Some examples are Globulin, Albumins, Histones, Albuminoids, Protamins, Glutelins and Globulins.
Conjugated proteins are simple proteins joined with a prosthetic group or cofactor. Some examples are Phospho- proteins, Chromo proteins, Nucleoproteins and Glycoproteins.
Derived proteins are obtained from simple proteins using the actions of chemical agents and enzymes and they are not naturally occurring proteins. Some examples include peptides, peptones and Metaproteins.
Simple proteins are proteins that are made up of amino acids joined by peptides bonds. Some examples are Globulin, Albumins and Gliadins.
Conjugated proteins are simple proteins joined with a prosthetic group or cofactor. Some examples are Phospho- proteins and Chromo proteins.
Derived proteins are obtained from simple proteins using the actions of chemical agents and enzymes and they are not naturally occurring proteins. Some examples include peptides and peptones.
Amino acids and proteins are the building blocks of life. When proteins are digested or broken down, amino acids are left. The human body needs a number of amino acids to:
- Break down food
- Repair body tissue
- Other body functions
Amino acids are classified into three groups:
There are three types of amino acids: essential amino acids, nonessential amino acids and conditional amino acids.
- The essential amino acids, we don't produce this, so we have to eat the food for obtain. The amino acids isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan and valine can not be synthesised by the body and therefore must be essential components of the diet. 
- Nonessential amino acids the body produce, so people don't need to eat for obtain this amino acids. They are: alanine, asparagine, aspartic acid, and glutamic acid.
- Conditional amino acids: If your system is stressed, out of balance, or diseased, these amino acids become essential and you must get them from food or supplements. They are: arginine, glycine, cystine, tyrosine, proline, glutamine and taurine.
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