A&P Lab Practical 2

Effect of amylase on cellulose

No effect because cellulose contains 1-4 beta glucose links whereas amylase can only work on 1-4 alpha glucose links such as those found in starch. Thus though both of these (cellulose and starch) are glucose polymers only starch can be digested by amylase.

Function of pepsin

Pepsin breaks down proteins that are found in foods such as meat and eggs into smaller pieces (polypeptides). It breaks down proteins only at certain points, so the protein is not digested completely to the amino acid level. In order for that to occur, the food has to pass into the intestines, where other enzymes complete the digestion process.

Effect of pH on pepsin

Pepsin has on optimum activity at pH 1.5-2.0 but retains significant activity up to pH 4.0. At pH 5.0 activity begins to decline as the pepsin protein denatures. This can result in autolysis of partially folded pepsin molecules by enzymes in their native state. Autolysis can be prevented by storing pepsin at pH 11.0 where all measurable activity is lose due to enzyme denaturation (activity is restored by lowering the pH below 4.0 )

What is pepsin?

Pepsin is a digestive enzyme that is released into the stomach as pepsinogen. The release of hydrochloric acid stimulates the release of this basic form of pepsin. When pepsinogen is exposed to the hydrochloric aid in the stomach, the pepsinogen unfolds and breaks into pepsin.

Function of amylase

break down starches

Function of lipase

lipase are enzymes, needed to break down lipids into the products glycerol and fatty acids.

Effect of pH on amylase

too low or too high causes enzyme to stop working; denature amylase

Effect of pH on lipase of bile salts

Bile salts are alkaline, so more salts = higher starting pH so LESS bile = LOWER pH Secondly, they are (WEAK) buffers too, so will tend to stabilize the pH (at an alkaline value) and so, if you have less bile, the pH will tend to fall more easily. *If you used bile salts as opposed to bile, this would not necessarily be true, the general point being: more bile=smaller oil droplets= faster breakdown to fatty acids=lower pH

Function of bile salts

Bile salts are produced in the liver. They act on fats, helping to emulsify them, making the into smaller globules so that they're easier to digest. Probably hydrolysis.

Effect of bacteria on cellulose

Cellulose cannot be digested without cellulase (enzyme) Animals with diets rich in cellulose, such as ruminants and termites, cannot make this enzyme. They are dependent on specific symbiotic bacteria which can synthesize this enzyme.