Digesting facts in the lab

Yasmin Jayathirtha

As we saw in the last column, enzymes are present in all living organisms. So, though experiments using enzymes appear to be beyond the reach of a school laboratory, we can set up qualitative experiments using natural extracts to illustrate the functions we study in the biology classes. Digestion, as I noted last time, is well worth illustrating through lab work.

glass-bowl_jelly Carbohydrate digestion is illustrated using salivary amylase. It is good to point out that many creatures are likely to have the same or similar enzymes to digest the same foods that human beings eat. So germinating seeds will have amylase to digest the stored carbohydrates for growth. It may be an interesting project to extract amylase from various seeds and compare their activities, either across varieties (grains vs. dals) or linked to germination times. These projects will be easily doable since all the material is easily available. However, they can lend themselves to very sophisticated ideas of research work including controls, what makes a fair test, etc.

After salivary amylase begins the digestion of carbohydrate in the mouth, the next lot of digestive enzymes is found in the stomach. This is not easy to get hold of, but as we see, other organisms have similar enzymes, so let us consider protein digestion, using enzymes from other sources. Traditionally, papaya and pineapple have been used to aid digestion, tenderize meat and applied to soften corns and warts. Both of them contain proteolytic enzymes, papain in papaya and bromelain in pineapple. These enzymes break down the protein collagen and so soften meat. Packages of jelly contain the instruction: do not add fresh cut pineapple, jelly will not set. We will look at this interesting statement later.

The author works with Centre for Learning, Bengaluru. She can be reached at yasmin.cfl@gmail.com.

This is an article for subscribers only. You may request the complete article by writing to us at editorial@teacherplus.org.