Biological Materials and Enzyme Action
Our laboratory experiments were divided into two parts, the first of which aimed at identifying various
classes of food (Part A), and the second of which aimed at understanding the work of enzymes and the digestion of
foods (Part B).
The compounds that we attempted to classify in Part A were carbohydrates, lipids, and proteins.
with nucleic acids, these constitute the four basic compounds of biological material.
Rather than testing a specific
hypothesis, we used various chemical techniques to merely identify the class to which various food samples
These tests were conducted based on the fact that biological compounds produce color reactions when
interacting with specific chemical reagents.
Starch (carbohydrate) reacts with iodine solution (IKI) to produce a
dark purple color.
Simple sugars (carbohydrates) react with Benedict's solution to produce a green or bright red-
Sudan IV dissolves in lipids and produces a red-orange color.
By mixing various food samples with
these chemicals, we were able to identify whether each sample contained starch, simple sugars, or lipids.
For Part B of our laboratory work, we tested the effects of pancreatic enzymes on the chemical breakdown,
or hydrolysis, of basic biological compounds.
Furthermore, we subjected the enzymes to different conditions so as
to observe the effects of temperature and pH on enzyme efficiency.
This included exposing the enzymes to a
combination of boiling, freezing, acidic, and basic conditions before allowing them to act on the compound samples.
We conducted our experiments based on the following hypothesis:
Pancreatic enzymes work most efficiently at
catalyzing the chemical reactions in biological systems when at 37 C (normal human body temperature).
further the temperature deviates in either direction, the less efficient the enzymes should be.
environment with a pH of 7 should be optimum for enzymes to function, with both acidic and basic conditions
minimizing their effects.
To test this hypothesis and the aforementioned classifying of food samples, we employed
the following methods.
Materials and Methods
For Part A, we began by testing for starch in four samples of food.
In each of four test tubes we placed a
small amount of potato scrapings, apple scrapings in water, egg white, and cracker crumbs in water.
We added a
few drops of iodine solution (IKI) to each test tube and observed any visible color change.