Biology, Eighth Edition (Raven)

Chapter 3: The Chemical Building Blocks of Life

Enzyme Action and the Hydrolysis of Sucrose

How does the body regulate the rate of metabolism? Metabolism is the sum of all the biochemical pathways in the cell. Catabolic pathways break down complex molecules to make energy available for biological work. Cellular respiration is an example of a catabolic process. Anabolic pathways build complex molecules from simpler components. Protein synthesis is an example of an anabolic process. Different pathways interact with one another to control the rate at which they operate. The end product of one pathway is often the initial substrate for a second pathway. If the second pathway is not active then the product will build up and reduce the rate of the first pathway. If the final product of the second pathway is in demand then the pathway will be active. Then the product of the first pathway will be continually used and the that pathway will remain active as well.

View the animation below, then complete the quiz to test your knowledge of the concept.


1.	Where is sucrose found in the human body?

		A)	on the gastric surface
		B)	in the liver
		C)	on the microvilli of the small intestine
		D)	in the pancreas

2.	In simple terms sucrase

		A)	joins glucose and fructose together to form sucrose.
		B)	breaks sucrose into glucose and fructose.
		C)	forms a disaccharide from a monosaccharide.
		D)	breaks sucrose into hydrogen, oxygen and carbon atoms.

3.	How does sucrose change the configuration of sucrase?

		A)	by significant trauma when they collide randomly
		B)	by changing the pH of the solvent
		C)	by force when under pressure
		D)	by binding to the active site

4.	How often can a sucrase molecule be used to hydrolyze sucrose?

		A)	once
		B)	twice
		C)	many times
		D)	never

5.	Blood sugar refers to what molecule circulating in blood?

		A)	glucose
		B)	sucrose
		C)	fructose
		D)	sucrase