Lab 7 - PhysioEx 8 Review: Digestive System Enzymes

Fill-in-the-blank practice flashcards covering digestive enzyme activity, specificity, temperature/pH assays, and experimental controls for amylase, pepsin, and lipase from PhysioEx 8.

During digestion, large molecules are broken down into smaller molecules via hydrolytic reactions known as __________.

hydrolysis

According to the diagram, the process where a normal protein loses its shape and function due to the breaking of weaker bonds is called __________.

denaturation

In the chemical reaction shown, two $\alpha\text{-D-glucose}$ monomers are joined to form maltose and water by an __________.

$$\alpha(1\rightarrow 4)\text{ glycosidic bond}$$

Maltose is a disaccharide of two glucose molecules, while maltotriose is a trisaccharide consisting of __________ glucose molecules.

$$3$$

The Iodine/potassium iodine (IKI) test detects the presence of starch or cellulose by turning __________.

blue-black

In Benedict's assay for reducing sugars, $\text{Copper (II)}$ ions are reduced to __________, forming a green or reddish/brown precipitate.

$$\text{Copper (I)}$$

In the amylase incubation time-course shown, as time progresses from $0$ to $10\text{ min}$, the Benedict's assay (BA) result shifts from light blue to __________.

reddish/brown

When starch is incubated at pH $7$ and $25^\circ\text{C}$ without amylase, the solution exhibits increased starch and decreased reducing sugar because there is __________.

no amylase in solution to act

Incubating amylase with starch at an acidic pH of $2$ and $25^\circ\text{C}$ results in high starch and high reducing sugar, which indicates __________.

reduced enzyme efficiency

When amylase and starch are incubated at pH $7$ and $100^\circ\text{C}$, the resulting high starch and low reducing sugar demonstrate that the amylase is __________.

not functional

Incubating amylase with starch at pH $7$ and $0^\circ\text{C}$ yields low starch and high reducing sugar, demonstrating that the amylase is __________.

functional

When amylase is incubated with cellulose at pH $7$ and $25^\circ\text{C}$, the positive IKI test and negative Benedict's test demonstrate that __________.

cellulose is not broken down

Incubating bacteria with cellulose at pH $7$ and $25^\circ\text{C}$ results in decreased IKI and increased Benedict's assay, showing that bacteria __________.

can breakdown cellulose

The digestive enzyme pepsin hydrolyzes proteins into __________.

small peptides + amino acids

In the BAPNA assay, hydrolysis by pepsin causes the release of a colorimetric dye that turns the solution __________.

yellow

In the BAPNA assay, the measured optical density (OD) is directly proportional to the __________.

degree of hydrolysis

At $25^\circ\text{C}$, pepsin hydrolyzes BAPNA at pH $2$ with an optical density (OD) of $0.4$, but at pH $7$ its activity is reduced, yielding an OD of __________.

$$0.03$$

When pepsin is incubated with BAPNA at pH $2$ and a boiling temperature of $100^\circ\text{C}$, the measured optical density is $0$, indicating that pepsin is __________.

inactive

As illustrated in the diagram, the digestive enzyme lipase hydrolyzes a triglyceride into a __________.

monoglyceride and fatty acids

In lipid digestion, bile breaks large triglycerides into tiny triglyceride droplets via the physical process of __________.

emulsification

Lipase activity can be tracked experimentally because the release of free fatty acids causes the pH of the reaction mixture to __________.

lower

When lipase is incubated with vegetable oil and bile salts at an initial pH of $7$, fatty acid production reduces the measured pH to __________.

$$6.21$$

When lipase is incubated with vegetable oil without bile salts at an initial pH of $7$, the measured pH after incubation remains __________.

$$7$$