Polypeptides
- Proteins are composed of polypeptides. These polypeptides are composed of chains of amino acids.
- These amino acids are linked together by condensation (dehydration synthesis). As all condensation reactions, one amino acid loses a Hydrogen atom and the other loses an OH molecule, creating water.
- When two amino acids are linked together, they form a dipeptide
- When 3 or more are linked together, they form a polypeptide
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Proteins
- Proteins may consist of a single polypeptide or multiple polypeptides
- Proteins are 3-dimentional. Each type of proteins has a unique shape. Since amino acids are placed in polypeptides one by one (in their specific sequence), the shape of the protein gradually changes until it reaches their final conformation
- Proteins can become denatured (change their conformation) by high temperatures and extremes in the pH levels
Functions of Proteins
Living organisms can create a variety of proteins with many different functions
•structural: collagen in connective tissue, spider silk
•contractile: actin and myosin in muscle tissue
• hormonal: insulin
• transport: hemoglobin
•protective: antibodies, immunoglobulins
•enzymatic: amylase, Rubisco
•pigments: rhodopsin (photoreceptor cells)
Proteome
Living organisms can create a variety of proteins with many different functions
•structural: collagen in connective tissue, spider silk
•contractile: actin and myosin in muscle tissue
• hormonal: insulin
• transport: hemoglobin
•protective: antibodies, immunoglobulins
•enzymatic: amylase, Rubisco
•pigments: rhodopsin (photoreceptor cells)
Proteome
- A proteome is all the proteins produced by a cell
- Each individual has a different proteome due to the difference of activities
- Each activity requires a specific protein, which is why each individual requires different kinds of proteins