Question 1
Question
Alpha helices are a helix-helix structure
Question 2
Question
Which of the following best describes an alpha helix?
Question 3
Question
Helix-helix packing can be shown by highlighting every _ residues?
Question 4
Question
Alpha helices must follow particular rules when packing together
Question 5
Question
Describe the ridges of the following proteins
Question 6
Question
The angle between two packed helices depends on which type of ridges pack into which troughs.
Question 7
Question
The troughs of one alpha helix will be filled by the 'backbone' of another
Question 8
Question
Beta sheets twist slightly _ each other
Question 9
Question
The angle between two beta sheets is approx....?
Answer
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30 degrees
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60 degrees
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90 degrees
Question 10
Question
Where in the plane is each color (ignore green)
Answer
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Yellow- above plane
White- below plane
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White- above plane
Yellow- below plane
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The amino acids will point in opposite directions
Question 11
Question
The strands of beta sheets are held together by backbone hydrogen bonding
Question 12
Question
The angle between sheets is determined by their...
Answer
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Right handed twist
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Left handed twist
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Length
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Amino acid side chains
Question 13
Question
How are the aa side chains arranged in beta sheets?
Answer
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The amino acid residue side chains of one beta sheet pack between the spaces between side chains on the adjacent beta sheet
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The amino acids on one beta sheet will have no residue where the other beta sheet has one (they're removed)
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The amino acids with residues attached will alternate between beta sheets
Question 14
Question
When an alpha helix and a beta sheet pack together, the groove the beta sheet lies in tends to be made by amino acids how far apart?
Question 15
Question
Name three things that can be used in protein folding to encourage correct folding?
Answer
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Non-native interactions (as long as they are reversible)
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Pinching (isolates subdomains for folding)
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The removal of a domain for folding, before it's re-addition
Question 16
Question
Negative Free Energy is less favorable
Question 17
Question
Concerning entropy- less order is more favorable
Question 18
Question
Which of the following is the equation for the free energy change of a folded protein
Answer
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ΔG = ΔH - TΔS
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ΔH = ΔG x TΔS
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TΔS = ΔH + ΔG
Question 19
Question
Hydrogen bonds are the least common type of bond in proteins
Question 20
Question
What's the enthalpy change of a H bond formation?
Answer
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-4 to -30 kJmol
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-4 to -3 kJmol
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-40 to -30 kJmol
Question 21
Question
A hydrophobic core in water is entropically favorable
Question 22
Question
Why is hydrophobic cores in water _favorable?
Answer
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They make the water molecules more ordered, decreasing entropy
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They make the water molecules less ordered, increasing entropy
Question 23
Question
Why do hydrophobic proteins fold?
Answer
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Folded proteins have a reduced surface area, leading to a reduced number of organised water molecules, leading to a lower decrease of entropy
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Folded proteins have a reduced surface area, leading to a reduced number of organised water molecules, leading to a lower increase of entropy
Question 24
Question
As water ordering decreases, entropy decreases
Question 25
Question
Why is energy needed to maintain the folding of a (hydrophobic) protein (i.e. from hydrogen bonds etc.)?
Answer
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Because the unfolded state of the protein is more entropically favorable than the folded state
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Because though the folded protein is more entropically favorable, it's folding decreases entropy, which is unfavorable
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So energy must be produced to maintain the fold
Question 26
Question
Heating denatures a protein because it breaks the bonds required to offset the negative change in entropy caused by the protein folding i.e, it makes ΔH less negative
Question 27
Question
In protein folding, ΔH is negative, and -TΔS is positive