1.6: Proteins Flashcards
Monomers of proteins
amino acids
Dipeptide
formed when 2 amino acids join together
Polypeptide
formed when more than 2 amino acids join together
Proteins made up of
one or more polypeptides
general structure of an amino acid
C single bond to COOH group (carboxyl group) single bond to H single bond to H2N (amine group) single bond to R group (variable group)
How many amino acids
20
Polypeptide formed by a
condensation reaction
Bonds formed between amino acids
peptide bonds
4 structural levels of proteins
primary
secondary
tertiary
quaternary
Primary structure of proteins
The sequence of amino acids in the polypeptide chain
Secondary structure of proteins
Hydrogen bonds form between the amino acids making the chain coil into an alpha helix or beta pleated sheet
Tertiary structure of proteins
Ionic bonds, more hydrogen bonds and sometimes disulfide bridges form in the chain, making it coil or fold more.
For proteins made from one polypeptide chain = final 3D structure
Quaternary structure of proteins
The way several differnet polypeptide chains are assembled.
For proteins made from more than one polypeptide chain = final 3D structure
Structural proteins
Consist of long polypeptide chains which are parallel to each other and have cross-links between them.
eg: keratin and collagen
Test for proteins
Biuret test