The Living World 8th Edition by George Johnson

تمرين 7

The catalysts that help an organism carry out needed chemical reactions are called
A) hormones.
B) enzymes.
C) reactants.
D) substrates.
In order for an enzyme to work properly,
A) it must have a particular shape.
B) the temperature must be within certain limits.
C) the pH must be within certain limits.
D) All of the above.
A restriction endonuclease is an enzyme that cuts DNA at a specific, unique sequence, like GAATTC. How does a particular restriction enzyme "know" when it has found its target sequence?
The enzyme sucrase splits the disaccharide sugar sucrose into the monosaccharides glucose and fructose. What prevents the glucose and fructose molecules from reentering the active site and reforming a sucrose molecule?
Which of the following is not a property of an enzyme?
A) An enzyme reduces the activation energy of a reaction.
B) The site on an enzyme that binds to the reactant is called the active site.
C) An enzyme is not affected by the reaction and can be used again.
D) An enzyme acts as a catalyst by being highly reactive and able to bind to any molecule in its vicinity.