Which of the following are CORRECT about protein structure?
- Secondary structure is formed by a repeating pattern of interactions among the polypeptide backbone atoms
- Tertiary structure is the three-dimensional arrangement of the polypeptide backbone atoms only
- Quaternary structure refers to an assembly of multiple polypeptide subunits
- $\text{P}$ and $\text{Q}$ Only
- $\text{P}$ and $\text{R}$ Only
- $\text{Q}$ and $\text{R}$ Only
- $\text{P, Q}$ and $\text{R}$