本题目来源于试卷: Interaction & Interdependence C.4 Chemical Signaling，类别为 IB生物学
[单选题]
Which features describe the t zh;8a5(cga ybqlj-h6m6wn e-ravzx8 mmy6 p28mnsmembrane receptor and intracellular receptor?
A. Signalling chemical enters the cell and binds in the nucleus /Signalling chemical remains outside of the cell and binds with the receptor
B. Located in the cytoplasm /Located in the cell membrane
C. Transmembrane domain contains hydrophobic amino acids and extracellular domain contains hydrophilic amino acids /Domain contains hydrophobic amino acids
D. An example is G protein-coupled receptor /An example is the tyrosine kinase receptor
参考答案: C
本题详细解析:
C The extracellular domain of transmembrane receptors binds to the ligand binding and often contains hydrophilic amino acids, which are capable of forming hydrogen bonds with water molecules. The transmembrane domain is mainly composed of hydrophobic amino acids to form a stable, nonpolar region that spans the hydrophobic lipid bilayer of the cell membrane. The Ligand-binding domain of intracellular receptors has a significant presence of hydrophobic amino acids as they bind with the hydrophobic, lipophilic, ligands. However, other types of amino acids are present in the ligand-binding domains of both types of receptors which contribute to the stability of the receptor-ligand complex and interactions with other molecules involved in the receptor's overall function. Therefore Choice C is correct. Choices A and B are incorrect because transmembrane receptors are found in the cell membrane. Therefore, the signalling chemicals remain outside the cell and bind with the receptor without entering the cell. On the other hand, intracellular receptors are found in the cytoplasm. Hence, signalling chemicals must enter the cell to bind with the receptor. Choice D is incorrect because both the G protein-coupled receptor and tyrosine kinase receptor are examples of transmembrane receptors.
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