IBDP Biology IA: Vocabulary Flashcards on Inhibition of Alpha-Amylase by Black Tea

Vocabulary flashcards covering key terms and concepts from the lecture notes on how black tea brewing temperature affects alpha-amylase inhibition, using DNS assay and spectrophotometry.

Alpha-amylase

Enzyme in saliva that hydrolyzes alpha-1,4-glycosidic bonds in starch, producing maltose and other smaller sugars.

Maltose

Disaccharide produced when alpha-amylase acts on starch; used as a metric for enzyme activity in this study.

3,5-Dinitrosalicylic acid (DNS)

Colorimetric reagent that reacts with reducing sugars to form a colored product measured at 540 nm to quantify maltose.

Spectrophotometry

Analytical method used to measure how much light a solution absorbs at a specific wavelength, here to quantify maltose via DNS.

Black tea inhibitors

Polyphenolic compounds in black tea that inhibit alpha-amylase activity, reducing maltose production.

Catechin polymerization products

Polyphenols formed from catechins in black tea (e.g., teaflavin-3-3′-digallate and thearubigin) that inhibit alpha-amylase.

Teaflavin-3-3′-digallate

A dimeric catechin polyphenol in black tea; one polymerization product that inhibits alpha-amylase.

Thearubigin

A class of polymerized catechin polyphenols in black tea contributing to alpha-amylase inhibition.

Non-competitive inhibition

Inhibitor binds to an enzyme at a site other than the active site, reducing maximum enzyme activity irrespective of substrate concentration.

Inhibitors release during brewing

As tea is heated, more inhibitors diffuse from leaves into the tea solution, increasing inhibitory potential.

Membrane fluidity

Temperature-dependent property of cell membranes that increases with heat, aiding release of inhibitors.

Brewing temperature

The temperature of water used to brew black tea; studied at 25, 40, 60, 80, and 100 °C.

Independent variable

The variable deliberately changed by the experimenter (brewing temperature) to observe effects.

Dependent variable

The measured outcome (level of alpha-amylase inhibition inferred from absorbance).

Absorbance

Optical density measured by a spectrophotometer; in this study, reflects maltose production and inhibition after blank correction.

Blank correction

Subtracting the absorbance of the original tea solution (without enzyme or starch) to correct for tea color/sugars.

Starch solution concentration

Prepared substrate concentration used (12.5 g/L) to standardize maltose production.

Alpha-amylase solution concentration

Enzyme preparation used (333 μg/mL) in reaction mixtures.

DNS volume

Volume of DNS reagent added per test tube (1 mL).

Wavelength 540 nm

Spectrophotometer setting corresponding to the maximum absorbance of the DNS-maltose complex.

Control group

Test tubes treated with distilled water (no tea/enzyme) to serve as a baseline.

Trials

Five repeated measurements per temperature to improve reliability of results.

Pearson correlation coefficient (PCC)

Statistics measuring linear association between variables; here r = -0.9812 between temperature and inhibition absorbance.

R-squared (R2)

Coefficient indicating how well the regression model explains data variability; here R2 = 0.9627.