Protein Structure 1
you know what to do
Select your name from the list.
Match the word or phrase to the explanation.
(1 point per match)
A. Interaction among more than one polypeptide chain mediated by "R" sidechains
B. folding of a single polypeptide chain into overall shape mediated by "R" sidechains
C. the trace through the common elements of each amino acid: amine, alpha carbon, carbonyl...repeating.
D. Folding of chain of amino acid residues into alpha helices or beta strands/sheets
E. the unique molecular component of each amino acid, with specific functional groups.
F. sequence of amino acids held together by peptide bonds
A helix that has one side that is hydrophobic and the other hydrophilic is known as
an amphibian helix
an alpha sheet
an amphipathic helix
a beta helix
Consult the amino acid chart above as needed.
A protein is found to contain two separate polypeptides, held together by a disulfide link between two cysteines. A mutation causes a change to the sequence of the protein so that one of those cysteines is changed to an alanine. A likely result of this would be
The quaternary structure would be less stable, perhaps preventing the protein from functioning
the protein would become too rigid to function
The secondary structure would be very different, converting alpha helices to beta sheets
Only the primary structure would be changed
Secondary structures are mediated by hydrogen bonds between amines and carbonyls that are part of the backbone of a polypeptide
The chart of amino acids lists several that are described as basic (shown in the chart in their conjugate acid, protonated form...with a positive charge). You might expect them to
lose the proton at low pH
gain another proton at high pH
remain positively charged at all pH values
lose the proton at high pH
The structure of a polypeptide is determined and it is found that it contains several alpha helices on its surface that are rich in hydrophobic amino acids (on the side facing out from the surface as well). What might explain this.
The protein is involved in synthesizing DNA
the protein functions in an aqueous environment
The protein is not functional
The protein functions in a hyrdrophobic environment, such as in the lipid bilayer
As the temperature increases above the protein's optimal temperature, the protein
denatures, losing all structure including primary structure
denatures, losing secondary and tertiary structure, but maintains primary structure
hydrolyses, losing all structure including primary structure
folds even more tightly into an insoluable ball
In the structure, where are the "R" side chains
"spoked" off from the helix
in the middle of the tube formed by the helix
it's a trick question, helices dont have "R" sidechains
making hydrogen bonds to hold the helix together
The picture shows the transition from unfolded to
complete secondary and tertiary structure
secondary structure only
completed primary structure
complete secondary, tertiary and quaternary structure