Q: Which of the following best describes the arrangement of hydrogen bonds in an $$b-$$sheet?

Hydrogen bonds are formed between adjacent $$b-$$strands.

Q: Which of the following structural features is most responsible for the elasticity of silk fibroin?

Close-packed $$b-$$sheets interrupted by compact folded regions

Question 1

Which level of protein structure is primarily responsible for the spatial arrangement of multiple polypeptide chains in a multisubunit complex?

Accepted Answer

Quaternary structure

Question 2

In an $$b-$$sheet, how are the side chains of neighboring amino acids oriented?

Accepted Answer

They alternate on opposite faces of the sheet.

Question 3

Which of the following interactions is NOT a favorable intramolecular enthalpic interaction that stabilizes protein structure?

Accepted Answer

Loss of conformational entropy

Question 4

A mutation replaces a hydrophobic residue in the interior of a globular protein with a charged residue. What is the most likely effect on protein stability?

Accepted Answer

Stability will decrease due to disruption of the hydrophobic effect.

Question 5

Which protein is characterized by a coiled-coil structure and is found in hair, fingernails, and intermediate filaments?

Accepted Answer

Keratin

Question 6

What is the main thermodynamic driving force for the burial of hydrophobic side chains in the interior of a folded protein?

Accepted Answer

Favorable gain of solvent entropy

Question 7

Which of the following best describes the arrangement of hydrogen bonds in an $$b-$$sheet?

Accepted Answer

Hydrogen bonds are formed between adjacent $$b-$$strands.

Question 8

A protein domain is typically defined as:

Accepted Answer

A region of ~200 amino acids that folds independently and often has a specific function.

Question 9

Which of the following structural features is most responsible for the elasticity of silk fibroin?

Accepted Answer

Close-packed $$b-$$sheets interrupted by compact folded regions

Question 10

Disulfide bonds in proteins serve to:

Accepted Answer

Greatly increase protein stability by covalently linking parts of the polypeptide chain.

Question 11

Which symmetry is displayed by a tetrameric enzyme with three 2-fold axes?

Accepted Answer

$$D_2$$ symmetry

Question 12

What is the effect of binding ions or prosthetic groups on protein stability?

Accepted Answer

It increases protein stability by providing additional interactions.

Question 13

Which of the following is a correct statement about the $$b-$$helix?

Accepted Answer

Side chains radiate out from the helix axis.

Question 14

A protein with helical symmetry, such as actin, is capable of:

Accepted Answer

Indefinite growth in length.

Question 15

Which of the following is NOT a fibrous protein?

Accepted Answer

Ubiquitin

Question 16

Which of the following statements about protein folding is correct?

Accepted Answer

Folding decreases conformational entropy but increases solvent entropy.

Question 17

Which of the following is a major difference between parallel and antiparallel $$b-$$sheets?

Accepted Answer

Parallel $$b-$$sheets have strands running in the same direction (N to C), while antiparallel $$b-$$sheets have strands running in opposite directions.

Question 18

Which of the following is a consequence of the densely packed nature of protein interiors?

Accepted Answer

Enhanced van der Waals interactions

Question 19

A mutation in collagen disrupts its triple helix structure. Which tissue is most likely to be affected?

Accepted Answer

Connective tissue

Question 20

Which of the following best describes the tertiary structure of a protein?

Accepted Answer

The spatial arrangement of secondary structural elements in the polypeptide chain

The Three-Dimensional Structure of Proteins (Chapter 6 Study Notes)

Guida di studio - Domande di pratica

Study guide - Flashcard