The two important types of secondary structures of proteins are the .......... and the ..............

Explanation

To answer the question about the two important types of secondary structures of proteins, we can follow these steps:

### Step-by-Step Solution:

1. **Understand Secondary Structure**: The secondary structure of proteins refers to the local folded structures that form within a protein due to interactions between the backbone atoms in the polypeptide chain.

2. **Identify the Types**: The two main types of secondary structures are:
- **Alpha Helix**: This structure is characterized by a right-handed coil where each turn of the helix contains about 3.6 amino acids. The backbone of the helix is stabilized by hydrogen bonds between the carbonyl oxygen of one amino acid and the amide hydrogen of another amino acid that is four residues earlier in the sequence.
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