Two major types of protein secondary structures are referred to as:

Question

BlackTom AI · Accepted Answer

Alpha helix and beta pleated sheet are the canonical secondary structural elements formed by hydrogen bonding patterns in the polypeptide backbone.

1. Relevant knowledge points and concepts
- Protein structure is described in hierarchical levels: primary (sequence), secondary (local backbone conformations), tertiary (3D folding of a single polypeptide), and quaternary (assembly of multiple polypeptides).
- Secondary structure arises from hydrogen bonds between the backbone N–H and C=O groups, producing regular patterns: the alpha (α) helix and the beta (β) pleated sheet.
- The α-helix is a right-handed coil stabilized by H-bonds between the carbonyl oxygen of residue i and the amide hydrogen of residue i+4. The β-sheet consists of β-strands aligned side-by-side, stabilized by inter-strand hydrogen bonds, and can be parallel or antiparallel.

2. Step-by-step reasoning process
- Identify what “types of protein secondary structures” refers to: forms produced by backbone hydrogen bonding patterns (not sequence or side-chain interactions).
- Compare the answer choices to the definition:
  - “alpha helix or beta pleated sheet” directly names the two classic secondary structures.
  - Other choices refer to different hierarchy levels or unrelated chemistry.

3. Calculations or intermediate steps
- No numerical calculation is required; reasoning is conceptual. Intermediate logical steps were: define secondary structure → list canonical examples → match to choices.

4. Why the correct answer is correct
- α-helix and β-pleated sheet are the standard, well-established secondary structures in proteins, each defined by characteristic backbone hydrogen-bonding patterns and repeating phi/psi angles in the Ramachandran map.

5. Why other options are incorrect
- “primary and secondary”: these are levels of structure, not examples of secondary-structure types.
- “tertiary and quatenary”: higher-order structures beyond secondary.
- “amino and carboxyl”: refer to functional groups on amino acids, not secondary structures.
- “residual and permanent”: not scientific classifications of protein structure.

6. Conclusion
This confirms the correct answer is “alpha helix or beta pleated sheet,” matching the provided answer.

Two major types of protein secondary structures are referred to as: 单项选择题

类似问题

In relation to a protein, what does the term Secondary Structure describe?

The alpha helix and beta pleated sheet make up the _______ structure of proteins.

The polypeptide's R groups in alpha helices---------------------and in the β-pleated sheet, hydrogen bonding between atoms on the polypeptide chain's backbone forms the "pleats". The R groups are attached to the carbons and -------------------- the pleat's folds.

The Aa pro is represented by which one of the following structures. Due to its structure it is usually not found in.............................

When discussing secondary structure, which one of the following best indicates how alpha-helices were described?

Which of the following best defines a protein’s secondary structure?

A beta sheet is an example of a secondary structure of a protein.

更多留学生实用工具

智能学习助手

风格化写作助手

论文查重助手

文献引用助手

课堂转译助手

课堂笔记助手

Quiz搜索助手

学校历年真题

智能刷题助手

智能匹配练习

希望你的学习变得更简单