69 Questions
Which type of protein structure is described as having polypeptide chains organized approximately parallel along a single axis?
Fibrous structure
Global 3D peptide structure with many different types, such as globular and fibrous, is referred to as?
Tertiary structure
Which type of proteins is characterized by being folded to a more or less spherical shape and tend to be soluble in water and salt solutions?
Globular proteins
Protein structures stabilized by interactions of amino acid side chains in nonneighboring regions of the polypeptide chain are referred to as?
Tertiary structure
Which part of the polypeptide chain describes the completely folded and compacted protein structure?
Tertiary structure
In globular proteins, where are most of the nonpolar side chains located?
Inside, buried within the protein
What is a molten globule?
A protein structure with native-like secondary structure but without a tightly packed protein interior
Which strategy do chaperones use to guide misfolded regions back into place?
Various folding assists
What characterizes intrinsically unstructured proteins?
They lack a well-structured three-dimensional fold
Under what conditions was the molten globule first found in cytochrome c?
Low pH and high salt concentration
What is the main feature of membrane proteins?
Exposed hydrophobic regions facing the lipid bilayer
Which process involves breaking the interactions stabilizing the native state of a protein?
Denaturation
What is denaturation of proteins?
The loss of the structural order that gives a protein its biological activity
Which of the following is NOT a cause of denaturation?
Formation of disulfide bonds
What type of proteins have hydrophobic residues inside?
Globular proteins
What is the role of molecular chaperones in protein folding?
Ensure proper protein folding or restore misfolded proteins
What happens to non-polar species in water according to the hydrophobic effect?
They reduce entropy in water
Which condition is necessary for proteins to renature back to their native structure?
Denaturation not being too severe
What is the name of the AI network developed by Google AI offshoot DeepMind for predicting protein structures?
AlphaFold
In which challenge did DeepMind's AlphaFold outperform around 100 other teams in predicting protein structures?
CASP Challenge
Who co-founded the CASP in 1994 to improve computational methods for predicting protein structures?
John Moult
What is the primary purpose of the CASP challenge mentioned in the text?
To assess protein structure prediction methods
Which term is used to describe the phenomenon of accurately determining a protein's 3D shape from its amino-acid sequence?
Protein Folding
What did John Moult, a computational biologist at the University of Maryland, create to enhance computational methods for predicting protein structures?
CASP Challenge
Which type of bonds are involved in the tertiary (3°) structure of proteins?
H-bond, electrostatic interaction, hydrophobic interaction
Which protein is found in the connective tissue of animals and provides structural support to cartilage, bones, teeth, skin, and blood vessels?
Collagen
What is the effect on O2 binding when CO2 levels and pH change in hemoglobin?
O2 binding to hemoglobin increases
Which protein has a hyperbolic oxygen-binding curve as opposed to a sigmoidal curve?
Myoglobin
What is the primary difference between myoglobin and hemoglobin regarding the number of oxygen molecules they can bind?
Myoglobin binds 1 O2 molecule, Hemoglobin binds 4 O2 molecules
Which forces play a significant role in proper protein folding?
Hydrogen bonding and hydrophobic interactions
What is the term used to describe a protein that conserves a native-like secondary structure content but lacks the tightly packed protein interior under low pH and high salt concentration?
Molten globule
Which proteins lack a well-structured three-dimensional fold and are encoded by many gene sequences in eukaryotic genomes?
Intrinsically unstructured proteins
What is the primary role of chaperones in the context of protein folding?
Guiding misfolded regions back into place
Membrane proteins are characterized by their association with which component of cells?
Cell membrane
What type of proteins are typically folded to a more or less spherical shape and tend to be soluble in water and salt solutions?
Globular proteins
What type of proteins are folded to a more or less spherical shape and tend to be soluble in water and salt solutions?
Globular proteins
What feature characterizes fibrous proteins?
They contain polypeptide chains organized approximately parallel along a single axis
Which type of bonds are involved in the tertiary (3°) structure of proteins?
Van der Waals forces
What is the effect of the hydrophobic effect on non-polar species in water?
They separate from water molecules
What describes the completely folded and compacted polypeptide chain in proteins?
Tertiary structure
What is the main cause of denaturation of proteins due to urea and guanidine?
Destabilization of hydrogen bonds
Which factor contributes significantly to protein aggregation associated with neurodegenerative diseases?
Heat-induced exposure of hydrophobic segments
What is the role of molecular chaperones in protein folding?
Assist in proper protein folding
Which type of protein structure is characterized by having hydrophobic residues located in the interior of the membrane?
Integral membrane proteins
What effect do non-polar species in water have according to the hydrophobic effect principle?
Decrease disorder in the water structure
What is the main achievement of DeepMind's AlphaFold mentioned in the text?
Outperforming 100 other teams in predicting protein structures
Which phenomenon is demonstrated when nonpolar side chains of proteins aggregate in water?
Hydrophobic effect
What is the primary cause of denaturation of proteins?
Changes in pH
In the context of protein folding, what is the role of molecular chaperones?
Guiding misfolded proteins back into their correct structures
Which feature best characterizes membrane proteins?
Integration into cell membranes
What effect does proper protein folding have on the protein's binding site and activity?
It leads to the proper binding site and activity
Which type of proteins tend to be mechanically strong, insoluble in water, and play important structural roles in nature?
Fibrous proteins
In which structure of proteins do hydrogen bonding, electrostatic interaction, and hydrophobic interaction play a significant role?
Tertiary structure
What is the main characteristic of intrinsically unstructured proteins?
They lack a well-structured three-dimensional fold
Where are the majority of the nonpolar side chains located in globular proteins?
Inside the protein away from the aqueous environment
What is the primary purpose of the CASP challenge mentioned in the text?
To improve computational methods for predicting protein structures
How are membrane proteins characterized?
By their association with lipid bilayers
What process involves breaking the interactions that stabilize the native state of a protein?
Denaturation
What feature characterizes proteins that have hydrophobic residues inside?
Having nonpolar side chains oriented towards the interior
How does the hydrophobic effect impact non-polar species in water?
Causes aggregation
What is the primary reason that proline disrupts the alpha-helix structure in proteins?
It lacks an N-H group for hydrogen bonding.
What is a common feature of the beta-pleated sheet structure in proteins?
Alternate parallel and antiparallel arrangement of polypeptide chains.
What characteristic differentiates the beta-pleated sheet from the alpha-helix in protein secondary structures?
Alpha-helix allows R groups to extend outward from the structure.
Which amino acid is commonly found in reverse turns of proteins due to spatial reasons?
Glycine
What is one factor that can disrupt the beta-pleated sheet structure in proteins?
Steric crowding caused by bulky side chains above and below the plane.
How does proline contribute to disrupting the alpha-helix structure?
Its side chain causes steric hindrance and a bend in the structure.
In protein secondary structures, which feature characterizes anti-parallel beta-sheets?
Alternate arrangement of polypeptide chains in opposite directions.
What is a characteristic feature of the secondary protein structure known as a reverse turn?
Flexible spatial arrangement with glycine residues.
Which factor is a significant contributor to disrupting an alpha-helix structure in proteins?
Strong electrostatic repulsion between positively charged side chains like Lysine or Arginine.
Test your knowledge on the denaturation of proteins, including the causes and effects of protein unfolding. Explore the factors such as pH changes, mercaptoethanol, detergents, heat, and urea that lead to denaturation.
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