Enzymes Lecture Notes Flashcards

A set of vocabulary flashcards covering enzyme practicals including amylase, catalase, and trypsin investigations, along with key experimental variables and chemical reactions.

Amylase

The enzyme responsible for breaking down starch into maltose.

Maltose

The product produced when the enzyme amylase breaks down starch.

Iodine

The indicator used to test for the presence of starch; it turns blue-black if starch is present (noted as black in the transcript).

Catalase

An enzyme often obtained from potato used to catalyze the breakdown of hydrogen peroxide ($H_2O_2$) into oxygen gas ($O_2$) and water ($H_2O$).

Catalase Chemical Equation

$$2H_2O_2(l) \xrightarrow{\text{catalase}} 2H_2O(l) + O_2(g)$$

Substrate Concentration Investigation

A practical where potato discs are placed in hydrogen peroxide solution; oxygen bubbles cause the disc to rise, and the time taken is measured.

Rate (General Formula)

The rate of an enzymatic reaction can be calculated using the formula $\frac{1}{\text{time taken}}$.

Trypsin

An enzyme used in experiments to break down the milk protein casein, turning a white opaque solution clear.

Casein

The opaque white milk protein that is hydrolyzed or broken down by trypsin into a clear solution.

Initial Rate of Reaction

The rate at the start of a reaction, calculated by drawing a tangent to the initial part of a curve on a graph and calculating the gradient in $\text{absorbance units}\,s^{-1}$.

Importance of Initial Rate

Measuring at the start ensures controlled variables like substrate concentration are the same, as substrate concentration declines rapidly once the reaction begins.

Optimum Temperature

The temperature at which an enzyme has its peak rate of reaction; in the trypsin investigation, this was identified as $35\,^\circ\text{C}$.

Denaturation

The process where high temperatures cause R-groups to vibrate and bonds to break, changing the shape of the enzyme's active site so the substrate cannot bind.

Independent Variable (Temperature Practical)

The factor intentionally changed in the experiment, which was the temperature ($20\,^\circ\text{C}$, $30\,^\circ\text{C}$, $40\,^\circ\text{C}$, and $50\,^\circ\text{C}$).

Dependent Variable (Temperature Practical)

The factor being measured, which was the rate of reaction in $\text{absorbance units}\,s^{-1}$.

Colorimeter

A device used to measure the transmittance or absorbance of light through a sample (like milk protein clearing) to track enzyme activity.

Systematic Error

An error that causes readings to be consistently higher or lower than the true value, such as using a scratched cuvette in a colorimeter.

Buffer

A substance that might be used to maintain pH at a suitable level for an enzyme-catalyzed reaction.