Protein Structure 1
you know what to do
Select your name from the list.
A helix that has one side that is hydrophobic and the other hydrophilic is known as
a beta helix
an alpha sheet
an amphibian helix
an amphipathic helix
The picture shows the transition from unfolded to
completed primary structure
complete secondary, tertiary and quaternary structure
complete secondary and tertiary structure
secondary structure only
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 high pH
gain another proton at high pH
remain positively charged at all pH values
lose the proton at low 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 functions in a hyrdrophobic environment, such as in the lipid bilayer
The protein is not functional
The protein is involved in synthesizing DNA
the protein functions in an aqueous environment
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
Only the primary structure would be changed
the protein would become too rigid to function
The secondary structure would be very different, converting alpha helices to beta sheets
Match the word or phrase to the explanation.
(1 point per match)
A. folding of a single polypeptide chain into overall shape mediated by "R" sidechains
B. sequence of amino acids held together by peptide bonds
C. the unique molecular component of each amino acid, with specific functional groups.
D. Folding of chain of amino acid residues into alpha helices or beta strands/sheets
E. Interaction among more than one polypeptide chain mediated by "R" sidechains
F. the trace through the common elements of each amino acid: amine, alpha carbon, carbonyl...repeating.
As the temperature increases above the protein's optimal temperature, the protein
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
denatures, losing all structure including primary structure
In the structure, where are the "R" side chains
it's a trick question, helices dont have "R" sidechains
making hydrogen bonds to hold the helix together
in the middle of the tube formed by the helix
"spoked" off from the helix