L4 Flashcards
List the 4 levels of organization of protein structure?
primary structure :
secondary structure :
tertiary structure:
quaternary structure:
describe the primary structure of proteins .
the primary structure of protein organization refers to the number and sequence of amino acids joined by peptide bonds.
how is the sequence of amino acids(primary structure) determined ?
the sequence is determined by genetics and it is coded in DNA
What determines the final 3D structure and function of a protein ?
sequence of amino acids
describe the secondary structure of proteins .
it refers to the conformation of the polypeptide chain by twisting or folding
what are the 2 major types of secondary structure and what makes them different?
the two major types are alpha-helix and beta sheet .
alpha- helix is a right handed helix structure that is stabilized by hydrogen bonds.Alpha-helix structure is formed by small and uncharged amino acids. bulky and charged amino acids prevent helix formation
beta sheet or beta pleated structure is composed of 2 or more segments of sully extended peptide chain
describe the tertiary structure of proteins .
it refers to the spatial relationship of distant amino acids in the same polypeptide chain
it is the 3-Dimentional arrangement of proteins
it is a compact structure with hydrophobic side chains held interior while the hydrophobic groups are on the surface of the molecule
what are the bonds that stabilize the tertiary structure?
disulfide bond (covalent)
electrostatic attractions
hydrogen bond
hydrophobic interactions
van der Waals interactions
describe the quaternary structure of proteins .
it refers to the spatial relationship between individual polypeptide chains in a multimeric protein .
the monomeric subunits are held by noncovalent bonds (hydrogen bandstand hydrophobic iterations and ionic bonds)
what are domains ?
domains are secondary-tertiary structures found in proteins associated with specific functions .
ex: antigen binding domain of the immunoglobulin
catalytic domain of an enzyme
what is the final structure of any protein made from one chain?
tertiary structure.
what happens to a protein after it is synthesized?
each protein undergoes folding to form a unique structure which is essential for its function after it is synthesized.
for example , the active site of the enzyme chymotrypsin is formed by polypeptide chain folding.
what other proteins help in the process of folding?
enzymes and chaperones .
what are chaperones ?
special proteins that help other proteins fold.
what is the denaturation of proteins ?
it is the change in native conformation of a protein .it occurs when there is a breakdown of quaternary , tertiary and secondary structure but the primary structure stays intact .
