Heather Sutcliffe
Digestive Physiology Lab Report
Bio 132-Spring 2015

Pre-Lab (see attached copies of worksheets.) Questions from pages 29-39
What is an enzyme?
An enzyme is a catalyst that works by speeding up the process of digestion. It is a substance produced by a living organism that acts as a catalyst to bring about a specific biochemical reaction.
How does an increase in temperature affect kinetic energy and enzyme activity? 1. An increase in temperature will lead to more energetic collisions.
When molecules collide, kinetic energy is converted into chemical potential energy. If the chemical potential energy of the molecule is great enough, the activation energy will be achieved and a change in chemical sate will occur. As temperature is increased, it is possible for more molecules per unit time to reach activation energy. This will allow the rate of reaction to increase.
2. The number of collisions per unit time will increase
Increasing the temperature of a system will increase the number of collisions of enzyme and substrate per unit time. This will cause the rate of reaction to increase. 3. The heat of the molecules in the system will increase.
What is denaturization of an enzyme?
Denaturization of an enzyme is the alteration of protein shape through some form of external stress. The enzyme will no longer be able to carry out its cellular functions.
How can an enzyme be denatured?
Heat and Acid will denature proteins, breaking hydrogen (H+) bonds. An enzyme is a protein. At high temperatures the shape will be altered, preventing it from performing its functions.
What is a buffer, and how does it work?
A buffer is a solution that resists change in pH when acid or alki is added to it. Buffers slow down the dissociation of the hydrogen (H+) bonds. A bugger helps regulate blood pH to maintain homeostasis. Buffers are a chemical substance or system that minimizes change in pH either by releasing or biding to hydrogen ions.
Fill in the following chart:

Enzyme used
Substrate digested in this lab
Product(s) formed
Carbohydrate Digestion
Amylase
Starch
Sugar & maltose
Lipid Digestion
Lipase
Cream (in litmus cream) contains 8% fat
Fatty Acids & Glycerol
Protein Digestion
Protease & peptidase
Albumin (egg white)
Small peptides and amino acids

What is a substrate?
A substrate is a medium in which a chemical reaction takes place. It is also the reagent in the reaction that provides a surface for absorption. Enzymes bind with chemical reactants called substrates.

What is a product?
The products are substances that formed during the chemical change. They are the things that are present at the end.
Carbohydrate Digestion – Effects of Temperature Changes
Hypothesis – prediction chart
Write in the expected color. (Iodine turns from yellow to black in the presence of starch)
Indicate the amount of starch present (++++ blue/black; +++ brown; ++ light brown; + dark yellow or – yellow).
Indicate the amount of maltose sugar present (+ green, ++ yellow, +++ orange)
Starch + Iodine =Black

0 min starch
5 min starch
10 min starch
15 min starch
20 min starch
25 min starch
30 min starch
30 min sugar
1 ice
Black
+++
Black
+++
Black
+++
Brown
+++
Brown
+++
Brown
+++
Brown
+++
+++
2 20 degree C
Black
+++
+
+
+
+
+
-
-
3 37 degree C
Black
+++
+
+
+
+
-
-
-
4 60 degree C
Black
+++
Blackish
++
Blackish
++
*
+
-
Yellow
-
Yellow
-
Oran./red
+++

5 100 degree C
Black
+++
Black
+++
Black
+++
Black
+++