Test
Quiz 6
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Preguntas del test (21)
1Which of the following is FALSE? DTT is used in protein studies as a-
- AAgent that absorbs hydrogen atoms from other molecules
- Bagent that can help with denaturation of a protein
- Cagent that can help with breaking of disulfide bridges
- Dreducing agent
2Urea, used at a high concentration, is an effective
- Areducing agent
- Bcaotropic agent
- Chydrogen donor
- Dchromophore, with a peak absorption at 28- nm
- Eendopeptidase, cleaving next to aromatic side chains
3Dialysis was used in Anfinsen's experiments as a means of
- APurifying RNAase A from small molecules
- Bremoving RNAase A from the solution
- CEnsuring the enzyme was maximally active at all steps of the procedure
- Dselective removal of chaotropic and reducing agents.
4Which is MOST CORRECT? Boiling a protein in a solution will always
- Acause denaturation
- Bturn the protein into a random coil
- Chave little effect unless the protein is also treated with a reducing agent
- Dbe a reversible process
- Eall of the above
5When the hydrophobic side chains of a protein in aqueous solution turn away from the proteins surface
- Athe protein undergoes denaturation
- Bentropy is decreased
- Cthe protein is stabilized
- Dhydrogen bonds are no longer possible
6Which of the following is false? A protein's native 3D structure --
- Ais the biologically active form
- Bis the lowest energy state of all possible conformations
- Cis the state in which entropy is the highest
- Dis the state that forms spontaneously in most proteins
- Enone of the answers are correct
7Hydrogen and ionic bonds contribute less than hydrophobic interactions to these ability of native aqueous proteins because
- Athey are not strong by individual bond energy comparison
- Bthey always tend to be buried inside the protein structure and therefore have little effect on stability
- Cwhen these bonds form energy has to be invested
- Dthe functional groups maintaining these bonds can form them as effectively in the random coil structure.
- Eall of the above
8The experimental procedure used to determine the precise arrangement of atoms within a large protein includes:
- Ax-ray defraction
- Bcrystallography
- C3D modeling tools
- Dworking with Rakmachandran plots
- EAll of the above
9Which is FALSE? The C—N bond between two residues in a peptide is different than a C—N bond in a simple amine because -
- AIt has no freedom of rotation
- BIt has partial double bond character
- CIt only allows for limited range of rotation, defined by the phi and psi angles.
- DIt is part of a resonance structure.
10A Rakmachandran Plot graphically displays
- Athe backbone of a protein
- Bthe amino acid sequence of a polypeptide.
- Cthe two angles of rotation of an alpha-carbon atom in a protein.
- Dthe pH of the solution as a function of OH equivalents added to the protein
11Glycine is typically the only amino acid to be found in the "white" areas of a Ramachandran plot. This is because-
- Aglycine is chiral
- Bglycine has no ionizable side chain
- Cglycine has a very small side chain
- Dglycine does not have an alpha carbon
- Ethe side chain of glycine is covalently connected to the alpha amino group
12Which of the following refers to particularly stable arrangements of amino acid residues in a protein that give rise to recurring patterns?
- Aprimary structure
- Bsecondary structure
- Ctertiary structure
- Dquaternary structure
- Enone of the above
13Which of the following groups participates in the type of hydrogen bonding that makes a beta-pleated sheet?
- A-N-H
- B-C-H
- C-C=C-
- D-O-H
- E-N-C
14The Phi Φ and Psi ψ angles of one alpha carbon located in the center of an alpha helix in myoglobin are -60o and -45o, respectively. Which of the following statements is CORRECT?
- AThe alpha carbon described above might belong to proline residue
- BThe alpha carbon described above has identical Phi and Psi as another alpha carbon in the protein
- CThe alpha carbon described above can have any set of phi and psi as long as it within the permissible areas of the Rakmachandran plot
- DThe alpha carbon described above has very similar phi and psi as its neighboring alpha carbons
15Proline residues.
- Aare typically found in the alpha helices due to their hydrophobic interactions
- Bare typically found in alpha helices due to their conformational flexibility
- Care typically found in alpha helices due to their tendency to form hydrogen bonds
- Dare typically found in alpha helices due to their tendencies to form ionic interactions
- Eare typically not found in alpha helices due to their conformational inflexibility.
16The structure of an alpha helix is maintained by
- Ahydrogen binding between the side chains of polar residues
- Bhydrogen bonding between the amide hydrogen in one side and the carbonyl oxygen on the other.
- CHydrophobic interactions
- DHydrophobic interactions in parallel beta sheets and hydrogen bonding in anti-parallel beta sheets.
17The major reason that antiparallel beta-stranded protein structures are more stable than parallel beta-stranded structures is that:
- Aparallel ones are in slightly less extended configuration than antiparallel strands.
- Bparallel ones do not have as many disulfide cross links between adjacent strands.
- Cparallel onces do not stack in sheets as well as antiparallel strands
- Dparallel ones have fewer hydrogen bonds than antiparallel strands
- Eparallel ones have weaker hydrogen bonds between adjacent strands
18A motif in proteins is
- AA distinct part of a protein that has its own independent structure and function
- Bsecondary structure
- Crepeating sequence in the primary structure
- Da super secondary structure that may be found in several different proteins.
- Ea non-polypeptide component of the total structure.
19A domain in proteins is
- Aa secondary structure
- Ba super secondary structure that may be found in several different proteins
- Ca distinct part of a protein that has its own independent structure and function
- Da repeating sequence in the primary structure
- Enon-polypeptide component of total structure.
20Which of the following is true?
- AEach peptide bond has some double-bond character due to resonance it cannot rotate.
- BThree bonds separate sequential alpha carbons in a polypeptide chain.
- CThe N--Ca bond in a polypeptide can rotate
- Dthe C-N bond in a polypeptide cannot rotate (carbonyl C)
- EAll of the above
21The peptide aspartylglutamylglycyltyrosylserine:
- Awill be easy dissolved in an aqueous solution
- BHas 5 peptide bonds
- CHas no free carboxyl group
- DIs mostly hydrophobic
Información
- Descripción
- Test sobre Quiz 6, creado por genny stubbs el 14/06/2017.
- Autor
- genny stubbs
- Idioma
- English
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