Pre-Lab 9: Environmental Factors on Enzyme Activity

A set of vocabulary terms and definitions covering the pre-lab assignment for studying enzyme activity under varying environmental conditions.

Purpose of the experiment

To observe how various environmental aspects will affect the reaction rate of enzymes.

Part 1 - Independent Variable

Different concentrations of enzymes

Part 1 - Dependent Variable

Rate of sucrase activity

Part 1 - Controlled Variable

Concentration of pH

Part 1 - Testable Question

How does enzyme concentration affect reaction rate?

Part 2 - Independent Variable

Different temps in water bath

Part 2 - Dependent Variable

Rate of sucrase activity

Part 2 - Controlled Variable

Concentration of pH

Part 2 - Testable Question

How does temperature affect reaction rate?

Part 3 - Independent Variable

Different pH buffers

Part 3 - Dependent Variable

Rate of sucrase activity

Part 3 - Controlled Variable

The temperature

Part 3 - Testable Question

How does pH affect reaction rate?

Test tubes

Used to hold and mix small volumes.

Test tube rack

Designed to hold multiple test tubes upright.

Test tube clamp

Used to hold a test tube securely.

$3\,ml$ Transfer pipette

Used to accurately measure and transfer small volumes of liquid.

$1\,ml$ Transfer pipette

Used to accurately measure and transfer even smaller volumes of liquid.

Adding pH $4.4$ buffer

Maintains a specific pH level for the reaction; must be added before the enzyme to ensure the environment is controlled.

Pre-heating tubes before Benedict's

Allows the enzyme and substrate to reach desired temperature to ensure temperature is a consistent variable during reaction.

Benedict's solution heating step

Tubes are heated in a $100^\circ C$ water bath for exactly $2$ minutes to allow the reagent to react with reducing sugars and show a reliable color change.

Enzyme Concentration Prediction

The highest concentration will show the greatest color change and the lowest concentration will show the least because enzyme activity increases with concentration.

Optimal Temperature Prediction

$37^\circ C$, as body temperature is ideal for enzymic activity.

Minimal Activity Temperature Predictions

$0^\circ C$ and $100^\circ C$

Optimal pH Prediction

pH $4.4$

Extreme pH Prediction

pH $1$ and pH $12$, which decrease activity because they are too extreme for efficiency.