orders of protein structure Flashcards
(14 cards)
What is the first structure of a protein called?
Primary structure
What is the primary structure?
the simplest level of protein structure; the sequence of amino acids in polypeptide chain
how is the protein sequence of the primary structure determined?
By DNA of gene that encodes the protein
What happens if there is a change in a gene’s DNA sequence?
Amino acid sequence will change, affecting protein’s structure and function
What is the second structure of a protein called?
Secondary structure
What is the secondary structure?
folded structures that form within a polypeptide due to interactions between atoms of the backbone (polypeptide chain apart from R groups; doesn’t involve R group chains)
What are the common folded structures in the secondary structure?
Alpha helix and beta pleated sheets
- both held in shape by hydrogen bonds, which form between carbonyl O of 1 amino acid and amino H of another
What is the third structure of a protein structure called?
tertiary structure
What is the tertiary structure?
a 3D polypeptide primarily due to interactions between R groups of amino acids that make up the protein
What are R group interactions?
non-covalent bonds (Hydrogen bond, ionic bond, dipole-dipole interaction, London dispersion forces)
What are hydrophobic interactions?
amino acids with nonpolar, hydrophobic R groups cluster together on inside of a protein, leaving hydrophilic amino acids on the outside to interact with the surrounding water molecules
What are disulfide bonds?
covalent linkages between sulfur-containing side chains of cysteines are stronger than other bonds that contribute to tertiary structure
- Act like molecule “safety pins”, keeping parts of polypeptide firmly attached to one another
What is the 4th structure of a protein called?
Quaternary structure
What is the quaternary structure?
some proteins are made of multiple polypeptide chains(subunits) that come together to give protein its 4th structure (ex: hemoglobin, DNA polymerase)
