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A signal peptide indicates the protein: A) Remains in the cytoplasm B) Forms aggregates C) Is enzymatically inactive D) Enters the secretory pathway

Highly conserved columns in MSA (>90% identical) indicate: A) Random variation B) Functional importance (catalytic residues, binding sites) C) Non-essential regions D) Recent evolutionary changes

In homology modeling using SWISS-MODEL, what does a QMEAN score closer to 1 indicate? A) Poor model quality B) No structural prediction possible C) Higher quality model  D) Model is identical to template

In molecular docking studies with lignin model compounds, which factor typically shows increasing binding efficiency? A) Decreasing ligand size B) Increasing ligand size (monomers < dimers < trimers < tetramers) C) Random variation D) Only pH changes

What is the primary difference between an alpha helix and beta sheet in terms of hydrogen bonding? A) Alpha helix has no hydrogen bonds B) Alpha helix has hydrogen bonds within the same chain (i to i+4), beta sheet between adjacent strands C) Beta sheets have no hydrogen bonds D) Both have identical hydrogen bonding patterns

A typical transmembrane helix consists of approximately: A) 5-10 amino acids B) 100-200 amino acids C) 50-100 amino acids D) 15-25 amino acids 

Variable regions in multiple sequence alignments often represent: A) Sites tolerating diversity (surface loops) B) Catalytic sites C) Strictly conserved structural cores D) Transmembrane domains

What does the “Small Molecules” tab in a PDB entry provide information about? A) The molecular weight and isoelectric point of the protein chain B) Details of non-protein ligands, cofactors, or drug molecules bound to the protein structure, including their chemical structure and ID  C) A summary of all mutations introduced into the protein during crystallization D) The solvent content and crystal packing parameters of the structure

The aliphatic index is an indicator of: A) Protein charge B) Thermal stability C) Protein size D) Enzymatic activity

High proline content affects: A) Protein charge B) Backbone flexibility C) Extinction coefficient D) Molecular weight only