Lab #9 - Starch, Casein, Gelatin, and DNA Tests

These flashcards cover the key concepts and terminology related to the lab tests for starch, casein, gelatin, and DNA, focusing on the role of exoenzymes.

Exoenzymes

Enzymes produced by bacteria that function outside the cell to break down large substrates for absorption.

Starch Test

A test to determine if a microorganism can produce a-amylase to hydrolyze starch into smaller sugar units.

a-Amylase

An enzyme produced by some bacteria to break down starch into glucose units.

Casein Test

A test to determine if a microorganism can produce enzymes to hydrolyze casein, a milk protein.

Gelatin Test

A test to determine if bacteria can produce enzymes to hydrolyze gelatin into liquid form.

DNase Test

A test to determine if a microorganism can produce DNase enzyme to break down DNA into nucleotides.

Hydrolysis

The chemical breakdown of a compound due to reaction with water; often involves enzymes like a-amylase.

Positive Result

Indicates the presence of an exoenzyme activity, typically shown by a clear zone around bacterial growth.

Negative Result

Indicates the absence of an exoenzyme activity, typically resulting in no change in the surrounding medium.

Gram's Iodine

A reagent used to test for the presence of starch; turns blue-black in the presence of starch.