Proteins Flashcards
What is a protein made out of
Chains of amino acids
What are the functional groups in an amino acid
Amino group
Carboxyl group
R group (variable region)
What is a dipeptide
2 amino acids covalently linked by a peptide bond
Define primary structure
Is the order of amino acids in a polypeptide chain
Define secondary structure
The folding held in place with hydrogen bonds into either a an alpha helix or beta plated sheet
What is an alpha helix
Polypeptide chain forms a spiral
Each amino acid forms hydrogen bonds with the amino acid 4 units along
What is a beta plated sheet
2 parts of the polypeptide chain lay side by side and hydrogen bonds form between them
Can a polypeptide have regions of both alpha helix and beta plated sheet
Yes
What is the tertiary structure of a protein
Final 3D shape of the folded polypeptide
The function of the protein depends on its final shape
What is the quaternary structure of a protein
Final 3D shape formed of more then one polypeptide chain
Bonds involved in tertiary and quaternary structures
Strongest. Disulphide bridges- covalent bonds that form between the sulphur atoms in the 2 cysteines
Ionic - form between oppositely charged R groups
Hydrogen- numerous but easily broken
Hydrophilic - form between polar R groups on the outside of the molecule
Weakest. Hydrophobic- form between non polar R groups inside the molecule
How do you disrupt a protein
Heat
Strong acids
What is denaturation
Process of disrupting protein structure by breaking the binds holding the tertiary structure together. Always causes loss of function
Features of globular proteins
Curled into a ball, non repeating sequences of amino acids
Often soluble
Hydrophobic and hydrophilic interactions
Function = metabolic
Eg insulin, enzymes
Features of fibrous proteins
Long and thin, regular repetitive sequences of amino acids
Insoluble
Function = structural
Eg collagen, elastin, keratin
