本题目来源于试卷: Interaction & Interdependence C.1 Enzymes & Metabolism，类别为 IB生物学
[单选题]
The following image shows the structure e)v.y zbg;(mii : fzs7of the lys o3+qjvv yjvbee+n).q( p f.kt,z 5p) fozyme enzyme. The darkened structure in black is the substrate and is bound at the act +fqzf ,5.yb3vn(+ ). vjvkeqop)t jpeive site.
Which of the following characterizes the active site of an enzyme?
A. It is rigid and cannot change its shape.
B. It has a binding site for a substrate(s) and catalyzes reactions.
C. It is always found in the middle of globular enzymes.
D. It is changed irreversibly in shape after binding with the substrate. Markscheme Diffic
参考答案: B
本题详细解析:
The active site of an enzyme has a binding site and a catalyt7+nhyju 8z qw2ic site. Once the substrate moves into the active site, the enzyme changes shape to accommodate the substrate better, making the substrate change shape so it is more likely tyqjhw+ 2z7 n8uo react and form a product. The active site is not rigid (Choice A) as it can change shape slightly to fit a substrate. The active site can be found anywhere in the protein (Choice C) and there can be more than one active site on an enzyme. An enzyme is not changed irreversibly by the reaction (Choice D). Once the reaction is completed, the enzyme reverts back to its original conformation and is ready to catalyze another reaction.
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