4: Protein Structure
Students identify levels of protein structure, distinguish alpha helices from beta sheets, analyze backbone hydrogen bonding patterns, and interpret Ramachandran plots.
LibreTexts reference: Unit 1, Chapter 4: Proteins- Structure and Folding 
Levels of Protein Structure
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Match each of the following levels of protein structure with their corresponding descriptions.
Note: Each choice will be used exactly once.
| Your Choice | Prompt | |
|---|---|---|
| 1. primary | ||
| 2. quaternary | ||
| 3. secondary | ||
| 4. tertiary |
Drag one of the choices below:
- A. linear arrangement of the amino acids connected by the peptide bonds
- B. β-strand locations within polypeptide backbone
- C. manner in which protein subunits are arranged in the native protein
- D. hydrogen bonding between polar side chains
Levels of Protein Structure
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Which one of the following levels of protein structure correspond to the description 'α-helix structures linked by backbone hydrogen bonding'.
Hydrogen Bonds in Alpha-Helix Structures
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The α-helix is a right-handed coil in which each backbone N–H group forms a hydrogen bond with the C=O group of an amino acid located a few residues away. The regular pattern of hydrogen bonding stabilizes the helix, preventing it from unraveling.
In a long α-helix, amino acid number 9 would form a hydrogen bond with which two other amino acids?
Select two correct answers.
Hydrogen Bonds in Alpha-Helix Structures
Click to show Hydrogen Bonds in Alpha-Helix Structures example problem
The α-helix is a right-handed coil in which each backbone N–H group forms a hydrogen bond with the C=O group of an amino acid located a few residues away. The regular pattern of hydrogen bonding stabilizes the helix, preventing it from unraveling.
In a long α-helix, amino acid number 11 would form a hydrogen bond with which two other amino acids?
Select the correct pair of amino acids below.