Experiment #1 - An Introduction to the Mammalian Digestive System

Introduction

Background Information

Cells are made up primarily of carbon, hydrogen, oxygen, and nitrogen, which form the building blocks of the basic cellular components: amino acids, simple sugars, nucleotides, and fatty acids. These building blocks are then assembled into cellular organelles. The energy required to assemble these macromolecules ultimately comes from plants that are capable of undergoing photosynthesis. Animals can obtain this energy by either eating the plant or eating a herbivore. Once eaten the essential nutrients are broken down into their simplest molecules by a process called digestion.

Enzymes are proteins that function as biochemical catalyst in animals. They are able to speed up the hydrolytic reactions needed for digestion, synthesis, and chemical communication. The important features of an enzyme include 1) the highly specific substrate the enzymes works on, 2) the binding site of the enzyme, and 3) the fact that the enzyme is not destroyed during hydrolytic reaction.

Digestion involves the breakdown of complex substances into simpler ones. Digestion takes place in ordered steps beginning with the enzymes secreted in the mouth, continuing with enzymes secreted in the stomach and ending with enzymes secreted in the small intestine. After digestion is complete absorption of the molecules takes place.

The process of digestion begins with mastication that serves to mix food with saliva containing the enzyme a-amylase. Next food is swallowed down the esophagus into the stomach where digestion continues in the presence of a gastric juice containing mucus, HCl, and the protease pepsin. Partially digested food is released in controlled amounts from the stomach into the small intestine via the pyloric sphincter. In the small intestine enzymes secreted from the pancreas and gall bladder (in the liver) enable the final breakdown of food substances into its simplest components which are then transported across the intestinal wall into the blood stream. After the small intestine the indigestible portions of food go into the large intestine where water and minerals are reabsorbed before finally being passed into the rectum and defecated through the anus.

Purpose

The purpose of this lab is to prepare an enzyme extract.

Hypothesis

There was no hypothesis for this lab.

Procedure

A 1.5 ml tube was marked and filled to the 5mm point with pancreatic powder prepared from pig tissue. Next 1ml of the enzyme extraction buffer containing the detergent NP-40 was added and the tube was capped and shaken for approximately three minutes. After this the particulate matter was allowed to settle to the bottom of the tube and the supernatant was extracted and placed into a new tube. The tube was labeled and placed in to the freezer for future use.

Results

There were no results in this lab other than the Pancreatic extract that was prepared.

Discussion

In preparing the Pancreatic extract it should be noted that the centrifugation option was not available for student use. This may affect the quality of the supernatant extracted in that small pieces of particulate matter may have been inadvertently collected. The consequences of this are that the supernatant would not be a homogeneous mixture and perhaps may manifest itself by irregular enzymatic activity.